Picked up an 07 in nice shape but low compression. I've been searching and I can't find an oversize piston available. I'd love to find an oversize with higher compression. Anyone know of a vendor?

 

Looks like Suzuki don't bother selling oversize pistons for them. You may get away with new rings. There probably won't be any "tuning parts" available for them, they are slower than slugs. The two stroke LT50 is a much better prospect for speed upgrades.

 

Maybe it a nikasil'd cylinder and don't need bored.

 

It's cast but I can not find an oversize piston

 

Have you actually had a look inside the engine. Your mention of a "cylinder base gasket" in the other post leads me to think you haven't. Adjust the valves, if that doesn't restore compression, take it apart and find out what it needs. Don't start messing with the compression, it is not going to increase power much. Get a hotter CDI as long as your little one isn't likely to over rev it. Putting all your posts on the one subject in one posting would be easier for everyone.

 

I have not opened the motor up yet.

 

"Putting all your posts on the one subject in one posting would be easier for everyone."

I see you ignored that advice. I would guess at about 110psi compression would be good, 90psi acceptable, and under 80psi it would be getting hard to start.

 

If I added more specific information to an existing post then whoever knows the answer would not open that post because it's titled differently.
I have used forums extensively through the years and I find it best to title your questions separately.

I've been researching as much as I can on this machine. O have seen one post so far that states that new it has 135 psi. I don't know if it's correct or not. I tested mine and it had 125

 

125 is great comp.
All this and we find out you don't even know what the correct comp is.
Merryman and I had to go from one post then back to your other post countless times trying to help (that's why 1 post is enough). NOW you finally tell us the current comp reading and it's fine.
FYI: your Z50 is a slug and is never going to be different. The Z90 is a slug also.
LT80 out.

 

I took the compression test yesterday shortly before I posted the question.
Yes I know it's slow. When I borrowed it from my buddy 3 years ago it would ever go up a small hill. I took an compression test then and probably had the same. I thought that 125 is weak for a 4 stroke. Most 4 stroke are over 150.
My buddy sold me the quad for $400 and it looks like new. So I can't go wrong. We have two small boys that can ride it. And when they out grow it on two years I'll sell it for $1000-1500
I ordered the dynoteck cdi. I'll gut th muffler and do the trans mod and reject the carb. If it still needs more I'll shave the head to bump the compression up.
I've done it before with good results on other quads.