Ok as to my previous problem posted, I am in need of a new 54mm piston and or just piston rings. I have bought 2 of them from Hetrick racing and am losing faith with their product. Well Im sure he has good stuff overall but what can you expect from chinese parts? The box says made in Taiwan!!! I know that its the piston rings cause I have an old one pulled from the previous set up with a non port and polished head and that piston and ring seems to fit very nice and the rings are of thicker material. But I dont want to risk it cause thats my back up. So any one know where I can get a new one?

 

Update, tried on old 54mm piston with new port and polished head from Hetrick and compression is only at 118psi. So I pulled everything off and slapped old head non port and polish with old 54mm piston and got compression to 125. Is it me or did Hetrick port and polish walls of head a little too much causing the compression problem?

 

You should get a matching set of piston & rings...They can have different tolerances and specs....Bore size is just 1 part of fit.

BTW....Most of the major ATV lines have their quads built in Taiwan or Vietnam......

Did you take a compression reading before the Hetrick modified parts were installed?

How are you testing compression? Does the tester take up the same amount room in the head as the spark plug you are using? Are you kicking it over about 10 times with the throttle held open? (this is how I have been told to test it)

Are you using fresh gaskets...

Is it running good?

 

I would ask hetrick about the compression with his setup..Sometimes porting can affect the compression at cranking speeds but the cylinder is actually fuller when the engine is running at high rpms...