gy6 157fm???? help

[NUT407]

Hello everybody!

Im new to this buggy forum, i stumbled upon it looking for parts on the interweb for my little beast. Im amazed at how popular these little buggys really are and how much effort people put into their builds!. Anywho I was under the assumption i own a hammerhead twister gokart with the 150cc gy6 clone. heres a happy snap of it.

[attachment=0]2012-12-02 16.04.53.jpg[/attachment]

It needs a little tlc but thats why i bought it, as a project a for a bit of a learning experience.

To cut a long story short, I need to get more power out of this thing as its pretty darn weak. (not to mention that the piston rings are shot ) my original idea was to get a honda cbr 250 and slam that in there but my welding skills are very very limited and dont want to deal with looking for a donor etc.

I noticed that you can buy big bore and stroker kits to increase displacement and figured this way would be alot easier (somewhat) to do. But have now found out that my gy6 150 aint the usual 157qmj. Its a 157fm and for the life me cant get any decent info on it.

Really what i want to know is if a big bore or stroker kit for the 157qmj will fit this because if im gonna replace the rings i may as well go hard or go home!.

Heres a couple pics of the engine (sorry im not the best photographer ;p)

2012-12-02 16.03.47.jpg

2012-12-02 16.04.01.jpg

2012-12-02 16.04.30.jpg

2012-12-02 16.04.39.jpg

2012-12-02 16.03.26.jpg

If anyone can provide me with any information i would gladly appreciate it!!

Thanks and safe motoring

[bear]

Welcome to the forum, you've come to the right place! first thing you gotta do is get with Tom @ sycpowersports! his banner is at the top of our page, his is the encyclopedia of info on all things buggy and can give you exactly what you need to make youre liitle buggy scream like you want it to and he's a heck of alot of fun to talk to so give him a call and he will hook you up!

[NUT407]

Okie dokie mate, il give him a try!

[NUT407]

Im still waiting for tom to reply, does anyone else know anything about this engine model?

[mb1134]

just be patient. Tom is a busy guy. He always gets back to you though.

[BuggyMaster]

Ya Tom would be your guy on this one. Just not sure myself. I know that generally speaking there are two different versions of this engine and the biggest change being a 2 bolt vs 4 bolt on the valve cover. The 4 bolt being the most popular and also the one with the most aftermarket availability regarding performance. However I know for a fact if you have the 2 bolt one that tom has some big bore kits for those.

[Johnny 5]

I would also check your carb pilot and main jet if it sat for some time . The pilot can plug up really easy. Also the intake boot can leak causing problems. The intake boot is about 10 bucks, we had a hesitation on our red buggy we bought used that also had bent valves. After fixing the valves it still hesitated,found the intake leaking causing a bad part throttle stumble.
The best performance for the least money is 10/11 gram rollers or sliders and a 1500 rpm torque spring.
This was my first upgrade that helped the stock 150cc engine stay in the power band and climb hills.
I just built a 62mm 3mm stroke motor (183cc) and it was fun but a 150cc with a good cylinder head and cam combo will work good if you dont want to dump alot of money in it.
I ported the head on our stock 150 engine 2 years ago and it made a huge gain, just dont go crazy on it. I cleaned up the intake and exhaust a little at a time with a dremel.
The big gain was probally the intake spacer was not matched to the head.
And I did not open the exhaust because it was already matched to the pipe gasket.
I ported heads before for my 68 chevelle and gained some top end. But without a flow bench it is guess work and comon sense.

Good luck and any questions I will try to help you with what has worked in my buggy trial and error experience over the years.

[x-bird]

if you find out anything about the "fm" coded engine from tom, post any info in this thread. Every so often people ask about them and no one seems to be able to provide an answer as to whether the more common qmj 4-bolt parts work with them.