I'm thinking I'll have to rebuilt the top end on my kids' quad. There's a ton of different choices out there regarding piston brand. Looks like Wiseco and OEM Suzuki are the most common.


Does anyone have a reason not to go with the Wiseco piston? I'm not going to bore the cylinder, just sticking with stock 50.00mm.

 

If you aren't boring the cylinder, then re-use your old piston. The clearence for a new Wiseco piston might (probably) be different then what the stock bore is.

 

Good to know. So I'd just need a top end rebuild kit minus the actual piston, right? I haven't seen a kit that doesn't include the piston.

 

Get a top end gasket kit and look for a stock bore ring set, a suzuki set for your suzuki piston. Then gap your rings.

 

Take a compression reading to see if u need a top end then inspect, rings won't do any good if the piston skirt is worn and slapping. If your considering a top end have piston measured if its factory sized go up 20 thousands and have cylinder bored to match. If compression is still around 100 psi and piston and cylinder doesn't look worn you may get by with rings and the cylinder honed to to freshen the crosshatch.

 

Like mentioned, measure the bottom of the piston and compare to the bore measurement. .007 up and you need a new bore and piston.
I've never been a rings only guy. All that work and you don't want a new piston for another 30 bucks???
To be honest, I'd get a .5 over piston and have it bored. Again, all that work and it won't be 100%.
Now to answer your question. I use Suzuki pistons. I'm a motor builder. I want the best.
powersportswarehouse.com for the best price. You will need to look up a 2003 KFS/KFX 80.

 

How do I know if my piston is stock? I'm getting an auto pick and better needle nose pliers today to remove those pesky circlips.


I'd hate to order new parts to find out my cylinder has already been bored.


Can someone look at these pictures and tell me if my cylinder is stock size?

 

I got the piston out with the help of a good set of automotive picks and some quality needle nose pliers. On the inside of the piston is has PROX and the number 22 embossed. It also says MADE IN JAPAN.


Can anyone tell me if this is a stock piston or an oversized one?


Thanks for the help.

 

It's aftermarket not sure about the 22. Is there a lot of carbon on top of piston if so clean off there may be a .5 or 1.0 on top of piston giving the size, no experience with pro-x pistons.

 

There indeed will be numbers on the top.