I recently had my cylinder bored by CT racing to accept a 51mm piston. I know I've got the reinstall right after following the manual. However, the piston did not slide into the cylinder without help from a rubber mallet and I could not pull it out or slide it in by hand. After completing the job, it was difficult to start, lacked power as I tried to break it in, and soon died at idle. I wouldn't start again. I would appreciate and knowledgable suggestions.

 

You need to take it all apart.
I suspect you installed the rings upside down.If they are stuck in the piston, pry them out as careful as possible. There are lil letters/numbers on the end of the ring. These go up.

To answer, there should be .003 to .0035 clearance between the cylinder and the piston for a Weisco piston. .0025 for a Suzuki piston..

Oh the knowledgable part..Throw that hammer away when it comes to motors. [img]i/expressions/face-icon-small-smile.gif[/img] LOL

Don't sweat it. A guy did this the other day that had loads more engine expierience than you. [img]i/expressions/face-icon-small-happy.gif[/img]

 

Thanks Jack, I even read that sentence in the manual twice and put the punch marks face down. "Each ring has a punched mark at its end and face it upside". The "upside" threw me off, they should have just said "up". I hope I didn't ruin anything.

 

ALSO, make sure ya line up the end gap of the rings with the little nubs/protusions in the ring slots. make sure it doesn't twist away from that spot as you slide piston into cylinder. i'd get another set of rings, but i think everything else should be okay.

 

I broke it down and put the rings right as LT80 suggested and centered the nubs fine. I used the same rings since there didn't appear to be any damage. It fires up and runs great now. On a side note, I have a moore modified motor w/ a trinity pipe. I had lost the exhaust flange for the pipe when I remove it to send out my cylinder, so to run the bike I had install the FMF pipe and silencer that I had before it got modified. With my son's bike, Jack was mostly correct in stating that the FMF doesn't perform well with his mods. It actually has a stronger low end pull and slightly less mid range hit, but its high rpm range is sorely lacking compared to the trinity pipe. I wonder if a larger main jet would change this?

 

I don't think jetting will help. It's a matter of exhaust pulse IMO.
That's the same results I had, Monster grunt, then it just flattened out and putted uo the road. [img]i/expressions/face-icon-small-smile.gif[/img]