The cast sleeves will not be true. Re: 2-Stroke 49cc Engine Help!! If you were to remove the pull start and try to rotate the part inside there, if it's siezed it will not spin. If the port opens low in the intake stroke to take advantage of the full upstroke of the piston, it will pump a great deal of the intake charge back out through the carb. if you were to put a vm 30mm (or 28, 32, etc. Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve quantity of the air flow. You might have to play around with the jetting of the carbi so the engine doesn't lean out at high revs or you'll melt the engine. If your boat is powered by an outboard motor, the trim tab will be attached to the bottom of the horizontal cavitation plate that looms above the propeller. For port work, one company that will help you is 2-Stroke-Porting. Being that the engine is unchanged from 2019, with a compression ratio of 7. 6mm smaller. It was the first production street motorcycle with capacitor discharge ignition (CDI). 4 stroke good points:-slower revving quieter lower fuel consumption clean flexible power lower emissions has more torque at lower speeds 2 stroke good points:-light weight high power uncomplicated (only three moving parts) can be used in any position 'X' torq engines have a porting system that. 2-strokes rely on the frequency of waves. I ride at 10,000ft+ and Im trying to get a little more torque from the engine. Notice how the exhaust of a 2-stroke is shaped. The EM2652LHN delivers commercial-duty power and performance, and is a step-up from older 2-stroke technology. If you are aiming for these qualities, modifying your 2-stroke engine is a great strategy. The two stroke engine was developed to obtain a greater output from the same size of engine. The motor has electric start, a 36mm Keihin Carb, case reeds, a six-speed gearbox and an electronic power valve. The new engine was torn completely down and inspected for deficiencies. Most after market pipes are not tuned to your specific engine porting mod's. Port Timing Basics Air/gasoline enters the engine from the carburetor at a ratio close to 15:1. One YS did peel from the boost port but I think it ate some dirt. For port work, one company that will help you is 2-Stroke-Porting. "Powerband" is the HP/torque curves of any engine. Sherco's 250 two-stroke motor is very similar to the 300 two-stroke aside from the bore, which is 5. The standing wave of the pipe is set so that the unburned air/fuel is shoved back into the port just before the port closes so the overall air/fuel charge is increased. I have an old 1963 classic 2 stroke motorcycle. November 22nd, 2019, 12:44 PM. Tithtening torque:::: Cylinder head nut::::15-18N. This question needs more details. The options are many. Unlocking the secrets of 2 stroke porting, part. HOWEVER, that does NOT mean it does not play a very big part in controlling or exacerbating this list, it does. if you were to put a vm 30mm (or 28, 32, etc. Processors with a lower number of cores will run the MOTA-X expansion chamber optimiser, as will the latest. Two Stroke Cylinder Porting Tips | WATCH THIS BEFORE YOU START CUTTING! 2 Stroke Tuning 2STROKE STUFFING. 2 into 1 & 3 into 1 expansion. RE: piston port induction vs. The gas tank was aluminum. Prop was 13D X 15P. More fuel efficiency :- 4 stroke engines have greater fuel efficiency than 2 stroke ones because fuel is consumed once every 4 strokes. The objective of porting a cylinder head is to improve engine performance via constructive enhancements to the intake and exhaust flow paths. A little assembly lube will help to keep the o-rings in place. 2 Stroke porting software for the enthusiast. Put enough hours on a 2 stroke engine and something will let go. However, you shouldn't just pick any business that you can find anywhere. Next, we torque the bolts to the manufacturer's specs. The sound was incredible from the triple pipes! In 1971 Polaris built a 439cc triple in addition to their 649cc and 795cc motors. 00 : No Core : Call Us : $1599. How A 2-Stroke Reed Valve Works. The cast sleeves will not be true. I have seen it mentioned a few times on here that torque is irrelevant in a 2 stroke and HP will always win out. We specialize in 2 stroke porting. The 300cc two-strokes GasGas available for 2020 include the EC 300, EC Ranger 300, and XC 300. 2 Stroke Engine Port Timing. 3. Remove spark plug cap. The bloc must be bored /*after*/ a powder coat. Two Stroke Performance Tuning Chapter 3 Porting and Cylinder Scavenging TODAY, when we take a look down the cylinder of a two-stroke engine, we find its walls literally filled with ports to handle the induction, transfer and exhaust phases of gas flow through the engine. China Hot Sale 2 Stroke 15HP Outboard Motor / Outboard Engine/ Boat Engine, Find details about China Boat, Engine from Hot Sale 2 Stroke 15HP Outboard Motor / Outboard Engine/ Boat Engine - Taizhou Yuelang Power Technology Co. When you want more 2-stroke power, look no further than Dick's Racing. The Morbidelli 125 twin road racer is a rotary valve engine. boosting torque there, and lowers the compression as it rises, allowing. Our goal is to achieve the biggest power gains as possible, while maintaining reliability on your 2-stroke engine. It made dreaded noises and came to a skidding stop in the middle. Hello all this is my first post on here. China Hot Sale 2 Stroke 15HP Outboard Motor / Outboard Engine/ Boat Engine, Find details about China Boat, Engine from Hot Sale 2 Stroke 15HP Outboard Motor / Outboard Engine/ Boat Engine - Taizhou Yuelang Power Technology Co. This is the second of a series of videos on the topic of 2 stroke engine ports that you need to know if you are intending to modify your engine. One field must have a value to calculate the other. The gas tank was aluminum. Typically a pressure wave return time is. This means that to run MOTA-X, you will need a post 2010 computer which is preferably a desktop, driven by an intel i7 4-core processor. 2 into 1 & 3 into 1 expansion. That's over a 50% increase in horsepower and 11 (ft-lbs) more torque. $350: Case porting: We port match upper case to bottom of cylinders, rough bottom and top case, epoxy bottom of case to stop air leaks before they happen. the wizard design the best expansion chamber for your specific application. This traps the charge of. Crankcase and Cylinder porting is probably the most controversial subject among Performance 2-Stroke engine builders. 94 ft lbs of torque at 10000 rpm. It was the first production street motorcycle with capacitor discharge ignition (CDI). RK Tek spent a better part of the 2008 Season developing a performance package for the new Rotax 800R (ETEC is the SAME ENGINE) Engine. You are correct in assuming that the port timing will be changed. Mine looks the exact same as in the photos posted by Smash in this previous thread, except his looks cleaner. we'll use 250 main jet and 40 pilot as an example. Thanks to all my patreon subscribers. Welcome to West Coast Porting. The options are many. Any OP can take a chain saw advance timing and lower port timing to increase torque, but sacrificing HP in the process. there seems to be a HUGE mis-understanding about port size and how it potentially effects your engines torque range, port size should be thought of more as a restriction to reaching necessary flow than a benefit to making a significant torque curve PROVIDED your matching the total engine component list to the intended rpm range and expected hp peaks the engine will be expected to produce and. Don’t Do It. This is a villiers 9E engine but it has a sports conversion 250cc head piston and barrel made by Marcelle. “I polish the exhaust port and the. Porting: These bikes make nearly 55rwhp with the right tune using the stock porting… so dont bother with cylinder porting unless you have a very specific application that requires maximum peak hp. 4-Stroke engines use a geared cam mechanism to operate the valves that control when air and fuel are admitted into the cylinder (intake timing) and when hot exhaust gas is evacuated out of the cylinder (exhaust timing). You should only rely on the experience of the very best. We call upon two-stroke genius Ted Boyko for the final word. 2 LTR : 2010-2018 : Rebuilt, 6 Cylinder F225,250 and 300hp 4- Stroke Short Block, 4. Our goal is to achieve the biggest power gains as possible, while maintaining reliability on your 2-stroke engine. Thread starter things as far as exhaust goes the closer the port goes to tdc you will get a tingy high reving rpm engine with less torque the lower the port is to tdc the more torque you get the reason that is the fuel that is burning is expanding so the longer you hold the expanding gasses the more power you get from it the. Let's get started. The steering torque tab (trim tab) on the outboard motor is there to combat steering torque generated by the asymmetrical forces of the propeller. What you are describing here is typical two-stroke characteristics. But pound for pound, a two stroke can't be beat. difference that you need to go from a 90 two stroke to a 100 four stroke to get the same top end. The engine color was also red. producing winning race machines. Valve Timing Diagram for 4-Stroke Engine (petrol and diesel) As we all know in 4-stroke engine the cycle completes in 4-strokes that are suction, compression, expansion and exhaust , The relation between the valves (inlet and outlet) and piston movement from TDC to BDC is represented by the graph known as valve timing diagram. This is not only true of my high speed F3D engine and ducted fan engines but of the low speed high pressure torque pattern engines. 622, which yields 376 ci. Ford has done this on many engines and they refer to it as split-port induction. The tradeoff was less torque (bottom end) with the shorter stroke motor. 5 Kg: Dimensions (L x W x H) (mm) 523 x 451 x 713. Porting cylinder heads generally refers to the process of enlarging the intake and exhaust ports of an engines cylinder heads. There is one or more forward-located exhaust ports, two or more side transfer ports, and one rear intake port. When I say increases HP, I should clarify it by saying HP at that given point in rpm that the saw operated at. The options are many. Port design in separate cad window: enter shape values, or drag port cursors; Limitations on CAD: Single exhaust port, single boost port; Purchasing options V4. Exhaust Extension for More Low RPM Power. When I say increases HP, I should clarify it by saying HP at that given point in rpm that the saw operated at. It's like the 4 stroke of the 2 strokes. Conversely an increase in diameter of the header will raise the engine speed at which max torque occurs,by approx the same RPM,for each 1/8 of increase. 0) and a stroke of 3. 4-stroke for speed: deserttoad: Fuel Plane Talk: 4: Oct 16, 2002 06:39 PM. Two strokes are not torque monsters. Crankcase and Cylinder porting is probably the most controversial subject among Performance 2-Stroke engine builders. PTEK Kit is $845. RK Tek is located in Preston, Idaho and is owned and operated by Kelsey and Rex (hence RK). However, that doesn't mean that there isn't a. 2 is the fact that they have fewer moving parts, which decreases the constant load on the engine, allowing it to burn the air-fuel mixture more efficiently, and reach. a 500 2 stroke already is a torque monster. 2 Cylinder Porting. Plans to Make a Torque Pipe. On a two-stroke engine, an expansion chamber or tuned pipe is a tuned exhaust system used to enhance its power output by improving its volumetric efficiency. Page 1 of 3 1 2 3 Next > TheBigGW LawnSite Member. November 22nd, 2019, 12:44 PM. Re: Detune 2-stroke for more torque I can't answer as far as how your 370 will feel when this is done, but I can answer two of your questions. Two Stroke Cylinder Porting Tips 7:54. The exhaust port opens and combustion gas starts down the pipe at supersonic speeds. The back transfer port is a unique design that runs inside the intake port divider, giving it the direction it needs for efficient scavenging, and at the same time allowing for maximum intake flow area. Also - the prop load on a hover is never as great as it is, simply sittling still on the ground. Many things will affect the power delivery of two-stroke motorcycle engines. The only thing you need to do for breakin is not over-heat or over-rev the motor, wide open is ok for short periods, just normal riding. Program features: Calculates port heights from durations, or durations from port heights; Assign fixed relationships between transfers and exhaust port. Sherco's 250 two-stroke motor is very similar to the 300 two-stroke aside from the bore, which is 5. The exhaust is designed along with the porting to give a certain power curve and the curves are usually quite narrow. there is a definite limit on how much porting you can do without raising the compression a significant amount though. Cylinder heads, as manufactured, are usually suboptimal for racing applications due to design and are made for maximum durability hence the thickness of the walls. The good thing about this place, is us fella's with differing view points can have these little debates without taking it personal like. 8 2-stroke - head bolts torque settings. 4-stroke for speed: deserttoad: Fuel Plane Talk: 4: Oct 16, 2002 06:39 PM. Air-cooled, equipped with centrifugal dry-clutch and integrated electrical starter. The ignition and power-valve timing were changed as well to give the power delivery a different personality. Porting and Cylinder Scavenging TODAY, when we take a look down the cylinder of a two-stroke engine, we find its walls literally filled with ports to handle the induction, transfer and exhaust phases of gas flow through the engine. The sudden hit of a 2-stroke that people refer to as "hitting the powerband" or "coming on the pipe" happens when the engine hits its sweet spot. Fill head with 50/50 mix of anti-freeze and water through the top cooling inlet. Anyways I am going to try to attempt to do a very minor port and polish on the *cylinder and intake on the kx 125. It is not there to correct for a list. 2L crate engine is now available. Cylinder Head Bolt Style: Torque to Yield (TTY) Cylinder Head Bolt Size (10) M11 x 2 x 100, (5) M8 x 1. How to Stop Torque Steer in a Boat If the stern moves to port, that means you need to exert a force on the starboard side of the motor. It uses a 2-stroke cycle to meet demands for high torque and 4-stroke for constant-throttle running. I don't know that I would consider this information the indisputable truth and it is fairly specific to these particular smaller cc cylinders, but it can be a very enlightening as to observable relations in altering 2 stroke port timing, enjoy: Relation of port timing to peak RPM, and Port timing for a specific 48cc cylinder, (this doesn't. HOWEVER, that does NOT mean it does not play a very big part in controlling or exacerbating this list, it does. The main reason for this is the fuel air mixture are getting mixed with the oil in the. Difference between a 2-Stroke and a 4-Stroke Engine are: 2- Stroke Engine : It has one revolution of crankshaft within one power stroke. Due to the thickness of the cast-iron cylinder liners, the LS3 block can be bored and stroked to. MACHINE SHOP SERVICES. This pipe produces 48 HP at 6500 RPM (10 HP over stock), delivers aggressive midrange acceleration and strong bottom end torque. 1 is the displacement, they generally have smaller combustion chambers, which means less fuel burned. Exhaust Extension for More Low RPM Power. In the interests of not cluttering up other threads, hp vs torque. 5 pilot, 6BFY43-74 needle 3rd clip, 430-450 main, AS 2. The rotary valve rotates past the crankcase intake port at a specific time to allow air through then seal the air into the crankcase. However, you shouldn’t just pick any business that you can find anywhere. That is, the piston will close the port the same number of degrees after TDC as it opened it before TDC in this setup. RK Tek SKI-DOO 800R/ETEC Drop In Piston Kit. If I did try the 'T' exhaust port, it would use two drilled auxiliary ports rather than trying to add a bridge. 622, which yields 376 ci. The bloc must be bored /*after*/ a powder coat. Variations of the engine were produced by Volkswagen plants worldwide from 1936 until 2006 for use in Volkswagen's own vehicles, notably the Type 1 (Beetle. You will need to modify the 4-speed cylinder by porting the exhaust to bring it upto 14BHP. More fuel efficiency :- 4 stroke engines have greater fuel efficiency than 2 stroke ones because fuel is consumed once every 4 strokes. and 250 main and 40 pilot. For example, my 96 engine is at Eric Gorrs right now being ported, and he said he could make it identical to the 01 engine by simply porting it the same. The 2-Stroke Cycle. Each engine type has their own advantages and disadvantages that will be clear by the time you finish this article. RK Tek sets itself apart from other performance shops by testing its products in the best lab in the world - the great outdoors. exe : one produces expansion chambers with a 2 stage diffuser and is DOS based, the other produces expansion chambers with a 3 stage diffuser, and is. Two stroke motors are more efficient that four strokes for a few reasons. You will not get the same characteristics out of a 120 2-T that you will out of a 110 4 stroke. also it cater for variable exhaust port timing and different fuels such as gasoline / petrol, ethanol / gasohol, methanol and methanol nitro mixes. Difference between a 2-Stroke and a 4-Stroke Engine are: 2- Stroke Engine : It has one revolution of crankshaft within one power stroke. We call upon two-stroke genius Ted Boyko for the final word. GPR STABILIZERS. 2 Stroke Engine Port Timing. You should only rely on the experience of the very best. Our goal is to achieve the biggest power gains as possible, while maintaining reliability on your 2-stroke engine. YZ125: Jetting: 40-42. Liquid-cooled, 4-stroke, Horizontal shaft, OHV: Number of cylinders: 2: Bore x stroke: 82 x 78 mm: Displacement: 824 cm³: Max. That's over a 50% increase in horsepower and 11 (ft-lbs) more torque. Hello all this is my first post on here. 0mm; we suspect that the engine performance will be the same as the 2019. The way to calculate the return timing and length of the negative wave in a 2 stroke expansion chamber is by this formula: WRT1=(D1x2)/SW where WRT1 is the wave return time for the first part of the wave, D1 is the distance from cylinder port to beginning of diffuser, and SW is the speed of the wave which is determined by the temperature and. Notes 2 A reduction in primary pipe Diameter of 1/8 of an inch will move the torque peak down by 650-800 RPM. For port work, one company that will help you is 2-Stroke-Porting. exe : one produces expansion chambers with a 2 stage diffuser and is DOS based, the other produces expansion chambers with a 3 stage diffuser, and is. I do know 2 strokes have almost no torque at low speed, so the throttle is open a lot at high demand and low rpm. Two Stroke Cylinder Porting Tips 7:54. The back transfer port is a unique design that runs inside the intake port divider, giving it the direction it needs for efficient scavenging, and at the same time allowing for maximum intake flow area. Crankcase and Cylinder porting is probably the most controversial subject among Performance 2-Stroke engine builders. It's like the 4 stroke of the 2 strokes. The process begins with a thorough examination of the parts and specifications, which are then evaluated with different computer programs to fine tune the design. 2009 Video of a pump gas RK Tek 860R racing a Polaris Dragon Turbo at 13PSI. This assures EVEN porting and proper flow! Please Look HERE for pics of the CNC porting. Most after market pipes are not tuned to your specific engine porting mod's. Bottom of Inlet Port Location Entering a value will produce Inlet timing figures. But higher imep ( related to far more more practical BMEP) caused by favorite topics like porting, compression, cam selection, exhaust tricks, carbs-n-manifolds, ignition timing, etc has a direct. Because t he optimisation process performed by MOTA_X is inherently slow, the use of facilities found in multi core processors is exploited in the code. Starboard Side Cylinder Head. Even if you gain no power porting but you move the exact same power up 2k you've made a faster stronger saw. Good for 2-3 HP. You can effectively change the "valve" timing of the 2-stroke by porting intake and exhuast up or down. The Latest. One field must have a value to calculate the other. Powerful 1/2 hp peak with full 1/3 hp under load. Porting your 2-Stroke motorized bicycle engine - Duration: 12:06. Welcome to porting-programs. RK Tek is porting cylinders using CNC Vertical Machining Centers (CNC porting). This is what is stage 1 porting in case of 4TL00 kits. On 2-strokes use a quallity synthetic 2-stroke racing oil and jet the carb with the same oil that you will be using. Just give us a call at 503-522-2465 to discuss your engine building needs. As someone said, it all gets pretty complex with a lot of compromises. In general, 4-stroke engines almost always make more torque at low RPM than 2-strokes. Use a quality torque wrench. worried about the torque loss but you can always help with the pedals but would like to retain and is completely free. Engineering Explained Recommended for you. also it cater for variable exhaust port timing and different fuels such as gasoline / petrol, ethanol / gasohol, methanol and methanol nitro mixes. We call upon two-stroke genius Ted Boyko for the final word. Port Timing Basics Air/gasoline enters the engine from the carburetor at a ratio close to 15:1. Leave 1 to 2mm of metal between the gasket and the holes. 2-Stroke porting/timing for torque? I was reading a thread about a 2 stroke versus a 4 stroke and it occurred to me that if the porting, or timing, of a 2 stroke could be changed, that maybe it's maximum torque range could be lowered to an rpm comparable to the 4 stroke, and thus swing the same prop as the 4 stroke. Heads with smaller ports – un-ported – usually provide better low-end torque than ported heads. The back transfer port is a unique design that runs inside the intake port divider, giving it the direction it needs for efficient scavenging, and at the same time allowing for maximum intake flow area. 10 ways to gain power in a 2 stroke engine for free!(or very cheap) You can buy alot of "go fast parts" and you can nerd out on complicated two stroke technology and finicky porting techniques but. 4 Complicating factors. HOWEVER, that does NOT mean it does not play a very big part in controlling or exacerbating this list, it does. That's over a 50% increase in horsepower and 11 (ft-lbs) more torque. Unlocking the secrets of 2 stroke porting, part. An engine "port" is an open window in the cylinder wall for the intake or exhaust of fuel mixture (air/gas). As the piston travels upward in the cylinder, it creates low pressure area in the crankcase; this draws. No fancy music or anything. Outdoor Power Equipment Forum. producing winning race machines. Porting torque. Welcome to West Coast Porting. Fast forward back to this past Saturday. Two Stroke Performance Tuning a disc partially cut away and attached to the end of the crankshaft opens and closes an inlet port in the side of the crankcase. Changing the port shapes increases or decreases the flow, thereby changing the RPM and torque characteristics of the engine. 10 ways to gain power in a 2 stroke engine for free!(or very cheap) You can buy alot of "go fast parts" and you can nerd out on complicated two stroke technology and finicky porting techniques but. Ok, since I am only planning on keeping the bike another year or so, I have decided, with the help of all you fine people, that the big bore kit is not the way to go to get more bottom end power out of my 01 CR125. I finally gave up on mine after several wheel, blade, bag, piston ring & crankshaft seal replacements through 25 yrs. It was not much of a surprise to find that Ski Doo. Porting your 2-Stroke motorized bicycle engine - Duration: 12:06. The cast sleeves will not be true. It enters via the intake port (as the piston rises) into the crankcase and then is transferred to the combustion area via the transfer ports (as the piston descends and the piston top uncovers the port opening to the cylinder). Discussion in ' Chainsaw ' started by pepsifreak28, Sep 11, 2009. Two strokes are all about making their power with high RPMs. Thread starter things as far as exhaust goes the closer the port goes to tdc you will get a tingy high reving rpm engine with less torque the lower the port is to tdc the more torque you get the reason that is the fuel that is burning is expanding so the longer you hold the expanding gasses the more power you get from it the. MACHINE SHOP SERVICES. YOU SHIP US YOUR PARTS - WE DO THE MODIFICATIONS/REPAIRS - WE SHIP BACK. 2 into 1 & 3 into 1 expansion. Play-by-Play: 2-Stroke engines only have one cycle to produce power and no cams. Piston Crown to Top of Barrel at TDC: Height over Port, Top of port to top of barrel: Exhause Duration (degrees): #N#Maico con rod kit and 40. Processors with a lower number of cores will run the MOTA-X expansion chamber optimiser, as will the latest. Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve quantity of the air flow. Unlocking the secrets of 2 stroke porting, part. YZ125: Jetting: 40-42. Starboard Side Cylinder Head. Each engine type has their own advantages and disadvantages that will be clear by the time you finish this article. These mods have helped a TON with the thin air, and the bike really rips, but I still wish for a little more bottom en. Also - the prop load on a hover is never as great as it is, simply sittling still on the ground. The stock MR175 motor develops 14hp at the rear wheel. if after porting the hp increases to say 5. RK Tek spent a better part of the 2008 Season developing a performance package for the new Rotax 800R (ETEC is the SAME ENGINE) Engine. 1245 Industrial Park Rd. 2- Stroke Engine : It can g. 2-stroke vs 4-Stroke Engine — Do you know the difference? This is a common question that our readers ask, especially those who are curious about how things work. Cheetah Cub and DM cyls. RE: piston port induction vs. The LT4 makes 195 horsepower and 195 ft. November 22nd, 2019, 12:44 PM. Horsepower vs Torque - A Simple Explanation - Duration: 7:24. It is not there to correct for a list. I have a year 2000 Tohatsu M9. Full metal foot control. Crankcase and Cylinder porting is probably the most controversial subject among Performance 2-Stroke engine builders. Don't see your bike above? We also offer custom engine building for many different applications such as dirt bikes, ATVs (both 2 & 4 stroke), vintage applications, and competition chainsaws. Porting torque vs hp. i have two images here that i have found on the web from a quick search that show the power and torque curves of a 2 stroke vs a 4 stroke 150hp modern outboard motor. My old 250 Single 2 stroke MZ is renowned for having very little torque available below 3000RPM, above that it does wake up though. 2009 Video of a pump gas RK Tek 860R racing a Polaris Dragon Turbo at 13PSI. There are 2 versions of Prog62. For port work, one company that will help you is 2-Stroke-Porting. Because torque and rpm are divided by 5252, torque and horsepower are always equal at 5252 rpm. The biggest change for 2019 is the weight loss, which comes from a new frame, a lithium battery and a long list of. Conventional two-stroke engine has number of advantages over four-stroke engines [2]. RA porting tool for transfer ports on 2 strokes Perfect Starter Kit for Port & Polishing 2 Stroke engines, includes right angle RA porting tool, flex shaft system, carbide porting burrs, and straight cylinder porting tool. 2 stroke oil ratios. Cylinder head nuts are known to become loose due to vibration. With a very versatile selection of tools, the 1082SR kit can also be used to modify 2 strokes above 150 cc and 2 strokes as small as 30 cc of displacement. On 2-strokes use a quallity synthetic 2-stroke racing oil and jet the carb with the same oil that you will be using. From five star rated high flow carb mods and cylinder porting, to cylinder head machining, piston anti-sieze mods and case matching. 1/2 HP peak output !. MACHINE SHOP SERVICES. If your boat is powered by an outboard motor, the trim tab will be attached to the bottom of the horizontal cavitation plate that looms above the propeller. Intake Extension for More Low RPM Power. Before you get to this point however, it's important to determine the rpm range of the desired power band and how you want to shape and position the torque curve to best suit your final application. Re: Detune 2-stroke for more torque I can't answer as far as how your 370 will feel when this is done, but I can answer two of your questions. I went out last Thursday and found the torque not much improved. - Cylinder porting - Different pipe - Case mods - Long rod conversion. We use computer design software to maximize power and torque at any elevation. ORG page 1 of 3 Engine Model Displace-ment cubic inches (cc) Bore Inches (mm) Stroke (mm) Power Output HP @ rpm RPM Range Weight w/muffler [w/o muffler] Power To Weight Ratio (hp/lbs) PCC_RC_Engine_SPECS. Variations of the engine were produced by Volkswagen plants worldwide from 1936 until 2006 for use in Volkswagen's own vehicles, notably the Type 1 (Beetle. Geoff Battick's Notes on 2 Stroke Engine Modification Article No. by Michael Forrest. STRENGTHS Considering the price, the size and the fact that it has oil -injection, we can see how it would appeal to an entry-level buyer, but the Xtrainer also attracts experienced off-road riders. Discussion in 'Chainsaws' started by Iron. Squish Velocity Calculator. For this Yamaha YZ250 motor, it was the crank after 250 hard hours. The other is how "Air Density" (barometric pressure, temp, humidity), and Elevation Change, affects horsepower. Porting torque vs hp. 8 2-stroke outboard, and I was hoping someone here could tell me what torque settings to use when reinstalling the head. Port design in separate cad window: enter shape values, or drag port cursors; Limitations on CAD: Single exhaust port, single boost port; Purchasing options V4. A single two-stroke engine produces pollution equivalent to that of 30 to 50 four-stroke automobiles[3]. very interesting question, let me give you an example, a basic 2 stroke you mentioned would be a 2 stroke without reed valves or any other valves, Mick Doohan's 500—4 Honda GP Bike had lots of trick valves that had over 180bhp, in 1973 Barry Sheen. It enters via the intake port (as the piston rises) into the crankcase and then is transferred to the combustion area via the transfer ports (as the piston descends and the piston top uncovers the. Horsepower vs Torque - A Simple Explanation - Duration: 7:24. Fast forward back to this past Saturday. Processors with a lower number of cores will run the MOTA-X expansion chamber optimiser, as will the latest. There is one or more forward-located exhaust ports, two or more side transfer ports, and one rear intake port. You will need to modify the 4-speed cylinder by porting the exhaust to bring it upto 14BHP. 2 stroke wizard tuned pipe pro version 5. Spend your money on head setup and ECU mods first. However, that doesn't mean that there isn't a. Exhaust port to be polished for smoother and faster exhaust gas exit. 2 into 1 & 3 into 1 expansion. Head Porting Our experienced craftsman enlarge and polish the passages and unmask the valve flow area, for more torque and top end power. The porting layout in a 2-stroke basically does the same thing a cam does in a 4-stroke, only Log in or Sign up. ROLL/ELKA SUSPENSION. Crankcase and Cylinder porting is probably the most controversial subject among Performance 2-Stroke engine builders. For more information go to DR. a 500 2 stroke already is a torque monster. producing winning race machines. What you are describing here is typical two-stroke characteristics. 2 Stroke Engine Port Timing. first things first here you got to understand how 2 stroke engines operate just because you know the basics dont mean. The cylinder pressure drops, and the fresh charge transfers thru the transfer ports, over the top of the piston, and out the. It moves the air in pulses or charges. if you were to put a vm 30mm (or 28, 32, etc. 622, which yields 376 ci. STRENGTHS Considering the price, the size and the fact that it has oil -injection, we can see how it would appeal to an entry-level buyer, but the Xtrainer also attracts experienced off-road riders. Intake Port Shape: Rectangle: Intake Runner Volume: 257cc: Exhaust Port Shape: D-Port: Exhaust Runner Volume: 87cc: Intake Valve Diameter: 2. The exhaust port was raised and the power valve reconfigured to match. 003 seconds. Air-cooled, equipped with centrifugal dry-clutch and integrated electrical starter. In this video we look how 2 strokes and 4 strokes produce torque and the difference between them. November 22nd, 2019, 12:44 PM. There is one or more forward-located exhaust ports, two or more side transfer ports, and one rear intake port. ) carb with the same needle/slide/etc. here is an overview of how two stroke motors work. But higher imep ( related to far more more practical BMEP) caused by favorite topics like porting, compression, cam selection, exhaust tricks, carbs-n-manifolds, ignition timing, etc has a direct. RE: piston port induction vs. Good for 2-3 HP. Cheetah Cub and DM cyls. These mods have helped a TON with the thin air, and the bike really rips, but I still wish for a little more bottom en. Being that the engine is unchanged from 2019, with a compression ratio of 7. I know nothing about milage or efficiency on these. The objective of porting a cylinder head is to improve engine performance via constructive enhancements to the intake and exhaust flow paths. This extra torque has a lot to do with the efficiency of the fuel burn; a 4-stroke uses almost all of its fuel to impart power to the crankshaft, whereas fuel crossover in a 2-stroke means that it will produce less power per RPM. I have a year 2000 Tohatsu M9. 4. Tighten the nuts evenly one by one to the their specified torque. I have a chance to pick one up very reasonably priced ok its a steal. producing winning race machines. A 2 stroke used in a chainsaw is a whole series of compromises. Due to the thickness of the cast-iron cylinder liners, the LS3 block can be bored and stroked to. Full metal foot control. Exhaust Duration Calculator. Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve quantity of the air flow. This is more or less true for a 4 stroke engine, but for a 2 stroke there are other factors to consider: 1. The engine color was also red. Play-by-Play: 2-Stroke engines only have one cycle to produce power and no cams. Or the OP can decrease timing advance porting to increase HP. Next, we torque the bolts to the manufacturer's specs. Step 5: Polishing. For port work, one company that will help you is 2-Stroke-Porting. worried about the torque loss but you can always help with the pedals but would like to retain and is completely free. HP = torque x rpm HP must have increased, and what enabled that was torque. Because t he optimisation process performed by MOTA_X is inherently slow, the use of facilities found in multi core processors is exploited in the code. Available for all models Available for all models ATP12999 (Larger valves and head machining also available. there is a definite limit on how much porting you can do without raising the compression a significant amount though. Anyways I am going to try to attempt to do a very minor port and polish on the *cylinder and intake on the kx 125. As someone said, it all gets pretty complex with a lot of compromises. ironically and I can't remember exactly, but i think for a 2 stroke, its higher compression for torque, and higher crank case compression for revs. How To Tear It Down. m Cylinder and cylinder head Remove carbon every 6000 km(4000. Our Engineered 2 Stroke Expansion Chambers are engineered to your engines porting specs. 2-Cycle, 2 stroke, 2C, engine porting kit, cylinder porting kit for 2 stroke motors PERFECT FOR TWO STROKE CYLINDER PORTING TXMC Hang-up Motor - HAS FULL POWER AT ANY SPEED which is essential for cutting and grinding on aluminum, plastic, or other soft metals or materials. 1245 Industrial Park Rd. 2-stroke vs 4-Stroke Engine — Do you know the difference? This is a common question that our readers ask, especially those who are curious about how things work. our famous 2 stroke expansion chamber calculator software. PAUL TURNER RACING 2 STROKE PIPES. The compression ratio is depending on A) the shape of your cylinder head and B) the stroke, bore and port timings. Use a racing sparkplug and premium unleaded fuel/2 stroke oil mix. Drag Porting: $550: Cub or Serval Play port: For those who don't want Drag only but are looking for more HP without much loss of torque. The LT4 makes 195 horsepower and 195 ft. The exhaust is a crucial part of a two stroke engines power curve. The good thing about this place, is us fella's with differing view points can have these little debates without taking it personal like. We do not need to know the height to the port. If the port opens low in the intake stroke to take advantage of the full upstroke of the piston, it will pump a great deal of the intake charge back out through the carb. I have learned nickel sleeve cannot withstand the rigors of our 2 cycle engines at elevated power, such as putting out. My old 250 Single 2 stroke MZ is renowned for having very little torque available below 3000RPM, above that it does wake up though. feel free to add to this thread all you fellow modders. Discussion in ' Chainsaw ' started by pepsifreak28, Sep 11, 2009. Exhaust Duration Calculator. The RZ500 stock engine produces 71 horsepower. How A 2-Stroke Reed Valve Works. NOTE: You engine may have a cylinder head gasket instead of o-rings. For Windows 98, XP, NT and Vista. Porting your 2-Stroke motorized bicycle engine - Duration: 12:06. Page 1 of 3 1 2 3 Next > TheBigGW LawnSite Member. It requires values for stroke, piston height, conrod length, and wrist pin offset. Part of the problem is understanding the "pulse" or "charge" nature of the airflow in a 2-stroke engine. More torque :-In general, 4 stroke engines always make extra torque than 2 stroke engine at low RPM. RK Tek is porting cylinders using CNC Vertical Machining Centers (CNC porting). Head Porting Our experienced craftsman enlarge and polish the passages and unmask the valve flow area, for more torque and top end power. The LT4 makes 195 horsepower and 195 ft. Rebuilt, 6 Cylinder F225,250 and 300hp 4- Stroke Short Block, 4. Engineering Explained Recommended for you. 0L, and the 1997 Windstar 3. torque: 59. if you were to put a vm 30mm (or 28, 32, etc. For this Yamaha YZ250 motor, it was the crank after 250 hard hours. We use computer design software to maximize power and torque at any elevation. Bigger carburetors, higher compression ratios, altered port timings and expansion. NOTE: You engine may have a cylinder head gasket instead of o-rings. Page 4-Question 2-Stroke porting/timing for torque? Engines Forums; Magazine piece although it slipped slightly off the subject of porting/timing for torque. Direct comparison between different types of exhausts for the two-stroke engine, on the left you can see the engine and its exhaust, in the. Modification of Two Stroke Engine to Increase the Torque Mechanical and Automobile IEEE Project Topics, Design and Analysis, Thermal Engineering Base Paper Ideas, Synopsis, Abstract, Report, Figures, Full PDF, Fabrication, Working details for Mechanical Engineering ME, Diploma, BTech, BE, MTech and MSc College Students. Your 2-stroke motor is an air pump. Unlocking the secrets of 2 stroke porting, part. Exhaust port to be polished for smoother and faster exhaust gas exit. Repeat those words over and over because once you feel a 325 Two-Stroke Torque (close to a 450) down low, you will kick yourself for waiting to buy the kit! S7 Woods Porting, Silver Head, Race Gas Dome, (Use Race/Pump Gas 50/50) Forum Main Moto-Related Yamaha YZ ESR 325 (2-T) Review. 0 litres: Dry weight: 57. You will need to modify the 4-speed cylinder by porting the exhaust to bring it upto 14BHP. A diesel is tourqe but a 2 stroke is hp A diesel doesn't need rpm to make power but it's the opposite with a saw. GT Crank 2mm eccentric pin & bearing. With a very versatile selection of tools, the 1082SR kit can also be used to modify 2 strokes above 150 cc and 2 strokes as small as 30 cc of displacement. Air-cooled, equipped with centrifugal dry-clutch and integrated electrical starter. at a different rate than aluminum. Timing in a piston controlled port is always "symetrical". The porting layout in a 2-stroke basically does the same thing a cam does in a 4-stroke, only Log in or Sign up. 2 stroke oil ratios. But assuming that we are talking about the same engine displacement in both cases, a two stroke engine will almost always produce more torque than a four stroke engine. Difference between a 2-Stroke and a 4-Stroke Engine are: 2- Stroke Engine : It has one revolution of crankshaft within one power stroke. Torque Converter Working, Principle, Main Parts and Application. With a very versatile selection of tools, the 1082SR kit can also be used to modify 2 strokes above 150 cc and 2 strokes as small as 30 cc of displacement. If the exhaust port begins to open at 80 degrees of rotation , the wave would return exactly when needed at 10,000 rpm because at that point, the time it takes for the piston to move from 80 degrees to 260 degrees is. if after porting the hp increases to say 5. 0mm; we suspect that the engine performance will be the same as the 2019. 2 times exhaust port area. All your 2 stroke specs in one spot --- Kawasaki, Suzuki, and Yamaha; Kawasaki Triples General Specs pg 1 General Specs Pg 2 Engine specs pg 1 Engine specs pg 2 Engine specs pg 3 Engine specs pg 4 Carb specs Chassis Specs Disk Brake CDI troubleshooting Maintenance specs Tune Up Specs Torque settings: Suzuki Twins Carb Specs Float settings. 80 ft lbs of torque at 10500 rpm. Heads with smaller ports – un-ported – usually provide better low-end torque than ported heads. here is an overview of how two stroke motors work. That is, the piston will close the port the same number of degrees after TDC as it opened it before TDC in this setup. Thread starter things as far as exhaust goes the closer the port goes to tdc you will get a tingy high reving rpm engine with less torque the lower the port is to tdc the more torque you get the reason that is the fuel that is burning is expanding so the longer you hold the expanding gasses the more power you get from it the. Cylinder head nuts are known to become loose due to vibration. The 2-Stroke Cycle. No fancy music or anything. Outdoor Power Equipment Forum. A 2 stroke used in a chainsaw is a whole series of compromises. we'll use 250 main jet and 40 pilot as an example. 8 hp) / 3600 rpm: Max. The porting layout in a 2-stroke basically does the same thing a cam does in a 4-stroke, only Log in or Sign up. 2 LTR : 2010-2018 : Rebuilt, 6 Cylinder F225,250 and 300hp 4- Stroke Short Block, 4. Porting your 2-Stroke motorized bicycle engine - Duration: 12:06. Modify Any Pipe For More Torque. I have a chance to pick one up very reasonably priced ok its a steal. I have over 38 years experience working with some of the best 2 stroke engineers in the world. Porting: These bikes make nearly 55rwhp with the right tune using the stock porting… so dont bother with cylinder porting unless you have a very specific application that requires maximum peak hp. in those industries have come up with quite a few innovations and inventions to help broaden the power curve of the 2-stroke engine and still maintain good peak RPM and HP. I have a year 2000 Tohatsu M9. a dellorto 14/14 SHA (73. I know nothing about milage or efficiency on these. I usually use a torque wrench with in-lb designations for low torque items like cylinder head nuts. Custom Engine Kits. ORG page 1 of 3 Engine Model Displace-ment cubic inches (cc) Bore Inches (mm) Stroke (mm) Power Output HP @ rpm RPM Range Weight w/muffler [w/o muffler] Power To Weight Ratio (hp/lbs) PCC_RC_Engine_SPECS. I have an old 1963 classic 2 stroke motorcycle. Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve quantity of the air flow. The multiple intake runner concept can also be employed on normal 2-valve engines. 2-STROKE ENGINE SPECIFICATIONS CHART Peninsula Channel Commanders (PCC) of San Francisco, California AMA charter Club #139 WWW. NEW exhaust system provides improved performance with reduced weight and a more durable construction thanks to the innovative corrugated surface on the expansion chamber. A bit of an overbore will help provided you can find a piston, but don't go wild or you'll reduce port volume too much and make a very peaky engine. If you solve the equation at 5252 rpm, the rpm value cancels out, leaving horsepower equal to torque. With cast-in sleeves, like Kawi 800 &1100, the cast iron sleeves expand. HP = torque x rpm HP must have increased, and what enabled that was torque. By exhaust port I mean the actual port in the liner not the port where the exhaust manifold bolts on. I finally gave up on mine after several wheel, blade, bag, piston ring & crankshaft seal replacements through 25 yrs. 00 : No Core : Call Us : $1599. With my porting, head modifications, and pipe I am able to make 110. The exhaust is designed along with the porting to give a certain power curve and the curves are usually quite narrow. There is an oil sump at the bottom of the the exhaust port and transfer port, which are normally almost opposite to each other. Sherco's 250 two-stroke motor is very similar to the 300 two-stroke aside from the bore, which is 5. Changing the port shapes increases or decreases the flow, thereby changing the RPM and torque characteristics of the engine. 1/2 HP peak output !. That's over a 50% increase in horsepower and 11 (ft-lbs) more torque. Also - the prop load on a hover is never as great as it is, simply sittling still on the ground. As the piston travels upward in the cylinder, it creates low pressure area in the crankcase; this draws. The motor has electric start, a 36mm Keihin Carb, case reeds, a six-speed gearbox and an electronic power valve. Tithtening torque:::: Cylinder head nut::::15-18N. Although 2 stroked ones give higher torque at higher RPM but it has a lot to do with fuel efficiency. edu is a platform for academics to share research papers. 1 is the displacement, they generally have smaller combustion chambers, which means less fuel burned. Conventional two-stroke engine has number of advantages over four-stroke engines [2]. I had installed an SE Sport 300 with clip and the porposing was better. A bit of an overbore will help provided you can find a piston, but don't go wild or you'll reduce port volume too much and make a very peaky engine. A head can be engineered for maximum power, or for minimum fuel usage and. Plans to Make a Torque Pipe. boosting torque there, and lowers the compression as it rises, allowing. [1] It featured a reliable aircooled, parallel twin, 6 speed (in some markets, such as the UK, the first model was sold in 5-speed form), reed valve equipped intake tract two-stroke engine. A 2 stroke will rev quicker but does not have the same torque/power as a 4 stroke. RK Tek 800 R Drop In Kit ANOTHER 12-26-1 RK Tek 800R Drop In Kit pulling a few hills in Idaho Dec 2012. The LT4 makes 195 horsepower and 195 ft. We have seen countless bikes come over our dyno with cylinder porting and all the latest bolt on mods making less torque than a stock bike. Now that we have brought this up again, remember that big cams and turbos and blowers all have a lag time. Bargain bin torque wrenches have been known to be way off. 2-stroke vs 4-Stroke Engine — Do you know the difference? This is a common question that our readers ask, especially those who are curious about how things work. It is not there to correct for a list. The 2000 version came with a new cylinder that was substantially improved. of torque more than its naturally aspirated cousin, the LT1. Piston Crown to Top of Barrel at TDC: Height over Port, Top of port to top of barrel: Exhause Duration (degrees): #N#Maico con rod kit and 40. The exhaust is a crucial part of a two stroke engines power curve. the wizard design the best expansion chamber for your specific application. Thread starter things as far as exhaust goes the closer the port goes to tdc you will get a tingy high reving rpm engine with less torque the lower the port is to tdc the more torque you get the reason that is the fuel that is burning is expanding so the longer you hold the expanding gasses the more power you get from it the. Port design in separate cad window: enter shape values, or drag port cursors; Limitations on CAD: Single exhaust port, single boost port; Purchasing options V4. Engineering Explained Recommended for you. 2 LTR : 2010-2018 : Rebuilt, 6 Cylinder F225,250 and 300hp 4- Stroke Short Block, 4. Two Stroke Cylinder Porting Tips | WATCH THIS BEFORE YOU START CUTTING! 2 Stroke Tuning 2STROKE STUFFING. A single two-stroke engine produces pollution equivalent to that of 30 to 50 four-stroke automobiles[3]. But what I'm saying is when you look at similarly suited stock 125cc 2 strokes compared with 250cc 4 strokes the 4 stroke is generally going to have more torque because of the heavier components and bigger bore and the 2 stroke is going to rev out faster and higher because of the lighter components, power on every stroke and no cam/valves to turn. The cylinder filling is taken care of by 2 piston controlled intake ports, five transfer passages and triple exhaust ports. One YS did peel from the boost port but I think it ate some dirt. Although 2 stroked ones give higher torque at higher RPM but it has a lot to do with fuel efficiency. FAT BOY 2 SILENCERS. I have over 38 years experience working with some of the best 2 stroke engineers in the world. But assuming that we are talking about the same engine displacement in both cases, a two stroke engine will almost always produce more torque than a four stroke engine. Put enough hours on a 2 stroke engine and something will let go. These were 6-port motors and featured CDI ignition. 2-stroke vs 4-Stroke Engine — Do you know the difference? This is a common question that our readers ask, especially those who are curious about how things work. Porting is usually done to increase airflow and horsepower at high RPM. Properly ported heads do not suffer that same malfunction! So let's get porting and polishing so you can enjoy more torque and more horsepower! Dr. Outdoor Power Equipment Forum. 94 ft lbs of torque at 10000 rpm. A single two-stroke engine produces pollution equivalent to that of 30 to 50 four-stroke automobiles[3]. Torque Converter Working, Principle, Main Parts and Application. The standing wave of the pipe is set so that the unburned air/fuel is shoved back into the port just before the port closes so the overall air/fuel charge is increased. 2 stroke wizard tuned pipe pro version 5. The way to calculate the return timing and length of the negative wave in a 2 stroke expansion chamber is by this formula: WRT1=(D1x2)/SW where WRT1 is the wave return time for the first part of the wave, D1 is the distance from cylinder port to beginning of diffuser, and SW is the speed of the wave which is determined by the temperature and. Compared to a four stroke, it is pretty easy getting equal or better torque to Horsepower numbers from four strokes. I have heard it said that by altering the effective height of the transfer ports - raising them up a little can make the motor produce more torque at lower RPM, and one way of doing this is to remove some material from the crown of the piston in the area of the. If I did try the 'T' exhaust port, it would use two drilled auxiliary ports rather than trying to add a bridge. RK Tek is located in Preston, Idaho and is owned and operated by Kelsey and Rex (hence RK). A little assembly lube will help to keep the o-rings in place. You will not get the same characteristics out of a 120 2-T that you will out of a 110 4 stroke. Hello all this is my first post on here. More torque :- In general, 4 stroke engines always make extra torque than 2 stroke engine at low RPM. Porting cylinder heads generally refers to the process of enlarging the intake and exhaust ports of an engines cylinder heads. There is one or more forward-located exhaust ports, two or more side transfer ports, and one rear intake port. Changing the port shapes increases or decreases the flow, thereby changing the RPM and torque characteristics of the engine. The Morbidelli 125 twin road racer is a rotary valve engine. RK Tek SKI-DOO 800R/ETEC Drop In Piston Kit. In general, 4-stroke engines almost always make more torque at low RPM than 2-strokes. A 2 stroke used in a chainsaw is a whole series of compromises. How A 2-Stroke Reed Valve Works. I don't trust my old torque wrench for more than tightening the lug nuts on my truck. SERDI VALVE SEAT MACHINING. It used port to inlet and outlet of fuel. Porting torque vs hp. If your boat is powered by an outboard motor, the trim tab will be attached to the bottom of the horizontal cavitation plate that looms above the propeller. These were 6-port motors and featured CDI ignition. 1- 44MC Tapered hand piece with 1/4" & 1/8" collet (cylinder head porting tool). A 2 stroke used in a chainsaw is a whole series of compromises. Direct comparison between different types of exhausts for the two-stroke engine, on the left you can see the engine and its exhaust, in the. Sherco's 250 two-stroke motor is very similar to the 300 two-stroke aside from the bore, which is 5. How to Stop Torque Steer in a Boat If the stern moves to port, that means you need to exert a force on the starboard side of the motor. You are correct in assuming that the port timing will be changed. Go over the entirety of the ports until they. It is very engine specific as to which modifications are needed and what can be done, so just doing a little porting can be good or bad. Powerful 1/2 hp peak with full 1/3 hp under load. Discussion in ' Chainsaw ' started by pepsifreak28, Sep 11, 2009. In 2004 the motor got upgraded again with a different bore and stroke; oddly enough the 250 and 300 would once again share the same stroke, but this time. The EC 300, like the 250cc model, has a new cylinder head lending to a more linear delivery of torque. If the port opens low in the intake stroke to take advantage of the full upstroke of the piston, it will pump a great deal of the intake charge back out through the carb. Most after market pipes are not tuned to your specific engine porting mod's. The objective of porting a cylinder head is to improve engine performance via constructive enhancements to the intake and exhaust flow paths. The options are many. 2 stroke oil ratios. The motor has electric start, a 36mm Keihin Carb, case reeds, a six-speed gearbox and an electronic power valve. 2-STROKE ENGINE SPECIFICATIONS CHART Peninsula Channel Commanders (PCC) of San Francisco, California AMA charter Club #139 WWW. Powerband Choices: Note that Changing the porting timing in a 2-stroke is the same as changing cam/timing in a 4-Stroke. This question needs more details.