Vertex vs. Wiseco pistons?

OE or ProX

^^^ This

If you were only going to decide between the two you listed I'd go with the Vertex because it's a cast piston and comes in sizes to fit to your bore.

What he said. Just make sure and measure the bore.

Full OEM top end, including gaskets and o-rings, for less than $125 shipped from http://www.hondaeasttoledo.net/OEMpartfinder.htm

I would choose Vertex over anything. They come stock on KTMs and I've never had any problems with them in about 10 years. The only brand I'd stay away from is Wossner.

I've tried just about every brand piston available for 2 strokes, and the only one that I'll never have anything to do with is Namura. An absolute refusal to stand behind a defective product never works well for me.

Imo, if you're going to stretch out the replacement intervals go with the Wiseco. Otherwise a quality cast piston is a great replacement.

ProX is a cast piston which is the same as OE. In some case it may even be the OE piston. I just bought ProX for my watercraft and they were marked ART inside. ART makes most of the OE pistons. I won't go into the difference between cast and forged. You can google it if you want but in the end, you will come to the conclusion. Both have their advantages and disadvantages.

Wiseco hands down, ProX if you want a cast piston.

The best piston I used in my YZ 250 was the Wiseco single ring "Racers Choice" The same piston fits the rm 250 as well.

Its lighter than stock. If your worried about ring wear, due to its single ring, use their Ti-nitride coated ring. Its expensive, but worth it. Consider it a hop up part for the bike. Part Number 808M06640 Its pretty fun in the bike, and will spoil you for anythign else. I ran mine 40 hours and it looked as if it had another 40 left. The coated ring is THAT good.

The standard Wiseco is a good choice also. I never tried Vertex. The Wiseco single ring is worth the extra $$$$. Plus, the specific sizes of the Vertex...your talking about such small differences, they are pretty much meaningless.

Its not like the old days when a piston had oversizes available from the factory. Its not like your trying to use a "second over" in a "third over" bore.

I wouldn't use a wiseco anything. Go with the OEM, or you will wish you did.

Sorry rcannon, it does matter. At least if you don't want that piston to slap and prematurely break the skirt. If you put an "A" piston in a clapped out cylinder, you get more slap, more wear, and yes, it's noticeable wear. Ask any experienced engine builder. No, it's not required, but does help.

Rule of thumb, if it's older than a season, put a "B" in it, minimum. If it's more than a couple seasons old, put a "C" or "D" in it, if the company offers it. That's if you don't know how to measure it or don't have the tools.

And Wiseco and OEM still do offer overbore sizes, but on limited models. Every .50mm is .020" bigger. When Pro X, Vertex, JE, CP and others talk about A, B, or C, they are talking about .01mm difference in piston size. That's tiny but it does make a slight difference when that piston is doing 12,000 rpm.