GY6 150 Stroker Engine

Update Oct 2012

Update 2013

This is a general ideal of parts that I use to build a powerful GY6 150 engine

Please understand that I had a 205cc engine built in 2009 that did not work out that well and even my measurements could have been wrong when I measure the Liquid in compression chamber. This one is for 180cc which I use what is given for parts description. All BOLT ON ALL PLUG and PLAY

Now take in mind I do not do any bore work althing it can be done, if so I will use brand new cases and build from ground up. Most consumers key into how big the cylinder or piston is which 63mm is largest for GY6 150. 61mm Cylinder Kits from Scootertronics that were tried and true tested from Straight Up Performance which is the company that does the research and design for Scootertronics. OK this means built installed in scooters and go carts and one motorcycle with great results.

Most important, on a brand new scooter I would suggest a big bore kit and exhaust to start. An older scooter everything needs to be replaced. You may also downgrade for savings on parts brand name.

Here is a list of parts used in one build for a carts and scooters for long and short cases


A few things have changed.

The article below was posted in Jan 2011.

Just so everyone who is considering a GY6 150 stroker kit which for the GY6150 engine the



performance crank is all that is added to a larger cylinder kit and cylinder head plus cam shaft, there are no off the shelf cylinder kits with piston kits that are are marked or have a description of GY6 150 stroker kit. Since I started writing about stroke cranks and so called kits so many websites, forums and blogs simply copied what I had written. The 205cc was from a post I wrote two years ago, there are no kits for this engine. The engine was built in the Scootertronics shop and the math I did gave me 205cc plus the engine screamed and took off great. The math to get cc’s is how liquid is in the compression chamber at TDC thats it and there was 2050cc and was a crude measurement. The internet does not forget so anything that was there years ago is still there even when improvements have been done. All the power had nothing to do with HP nor CC’s. Most likely I could have gotten the same results for  a scooter engine with a  59mm piston plus 61mm head paired with CVT parts that gave the Torque needed for the performance. Its torque you need not HP. The right high performance parts in the CVT with the right rider will pull the wheel off the ground everytime. Personally I am not the best rider or trick guy or racer. But I can easily pull the front wheel off the ground from a dead stop or while ridding. My understanding of the engine and when it will happen makes it easy.

My point is I have all the parts. The crank, cylinder kits and heads plus cams carbs and all CVT parts. The 61mm kits I offer drop in almost every GY6 engine, not SYM or Tomos or Lance which are all SYM. The 62, 63mm all need bore which I have a tool plus offer cases ready to go.. However I would suggest a slamming CVT way before I would suggest 62 or 63 this is over kill and the rest of engine is not done.. Get the right pipe, up gears parts, carb and intake plus air intake. . Now if you are trying to build the biggest sure bore it out and use 63mm but I have not found anymore speed from a 63mm piston than a 61mm piston when everything else is stock. A 61mm kit with cam and head goes a long way when using a fine tuned CVT with NCY vaiator, Koso clutch, MRP bell plus 32mm carb and air intake. Really just the air intake makes a huge difference in your scooter.

My biggest point and its all over the media as in TV DON”T believe everything you read online. Look at the date it  was written and who wrote it. Consumers are reading forums and blog post written 6 years ago that first were wrong and have nothing to do with today’s scooters.

When considering doing this to get your 150 scooter screaming with power and top speed how fast can you really ride on the street. If racing completely different story but I have never had one call for an engine for someone racing. Most scooter racing is done on two stroke scooters mod to 70 or 90. We have a few 150s that race with us so yes these scooters would be a good candidate.

To build an engine correctly you need not to only get a bigger piston and cylinder and head, but a cam, carb, intake, air filter, variator,  crank, clutch, clutch bell, belt, roller weights, maybe gears. So you see there is more to it. Now of course you can use stock parts on engine but why they will not transfer the power. Putting 170cc into to stock CVT drive with an old belt, rollers, clutch will NOT produce the desired effect which for most is top end speed.

The big bore kits on the market range from cheap to expensive. Adding a cheap 61/63mm cylinder kit and doing a bore job and not adding a head to match, Kevlar belt, quality rollers weights and yes a new clutch and bell you will simply break your belt, use up your weights, and your clutch will start to slip the the first day. Plus what about exhaust. Try pushing out all that new found air through the same header. It happens, customers call and tell me. I am now replacing these parts along with cylinder kits and cranks because they used stock cranks that broke and ruined cylinders and piston plus they never even used a larger head so they were pushing air against metal and try to get it out the same small valves and oh so small header and bent the rod trying to get every once of speed after they built up a 150 without getting tags got caught and now have tickets also. Ok I am going nuts I know but there is no magic bullet.

Its simple to get the performance you need to commute on a scooter on the highway and freeway. Consider the cost of building your 150 engine to do what you want, great take off, 70mph which gets you tickets, wheelies which messes you up and faster than the other guy you are ridding with right. Now you have spent 1000 – 1500 got the correct parts, built the engine or had someone do it when you can buy a quality Keeway or CF Moto 150 Liquid Cooled 65mph scooter, the whole scooter with a warranty or even better yet buy a 250 for 2199 and ride on the freeway with tons of room, power, quality that will last way longer than you will even ride. I know eveyone will say I can buy the parts cheaper yep you can cheaper means cheaper parts. I am not saying this is for everyone but add up your dollars you have spent, see the end result first.

Do not get me wrong I am all for high performance parts I really am, but I am more able and willing to show consumers a better route and its certainly not for a bigger profit on my end. Everyone knows parts bring better profit they are certainly easier to stock , ship, maintain and so on you get the picture.

Since 2003 its been my mission to do my best. Which is why today I secured at least 6 new types of CDIs that are No Rev Limit for scooters that I have not been able to provide till now. These are Kymco Super 9 AC/LC two stroke, TGB 50RX two stroke, SYM, Hyosung and of course new ones for GY6 50/150 so this includes all Kymco 50/150 4T Kawasuki 4T 50 ATVs, Piaggio also,  250s are next just need to test.

Parts at the shop had them out so I could put some out of stock around the shop

If you have comments please post, it helps me do my best


One response to “GY6 150 Stroker Engine

  1. Hi I’m from south africa I got a 125 euro trac gy6 clone its a long case I guted the exuast and put a bigger mukini carb on with 15g rollers . Anyway I have read a lot of posts and blogs about the big bore kits and heads but one thing I’ve seen is that here by us parts are avalible but not what I whant . I was wandering if seen chinese atv with 200cc gy6 looking engines in do you think they will be a better bet my engine is a lc152qmi and the atv engine I have is a 162qmk

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s