We've looked around, and all we can find is Wiseco's that go up to .040, which is what the cylinder is at now. It needs a fresh bore, and it looks like it can be bored more, we just can't find the piston he needs. Can anyone give me some info as to why??

 

nacs racing should have them. they have website.

 

Water cooled R's can be punched to .120. My R is currently at .080 without any problems.

I like wiesco pistons in four strokes and 2-strokes that use "window" pistons (Banshees, blasters, dirtbikes, have two square holes in intake skirt). But ProX is the best to use in engines that use the cutaway intake skirt (R's, CR's have half round cutaway). The forged wiesco needs a lot more room for expansion and must be bored loosely. Without the lower portion of the skirt, the piston in a 250R motor can rock more than "windowed" motors. The ProX is hypereutectic. They don't expand as much and can be bored tighter, giving less room to rock, so it last longer.

I know FTZ stocks every size of ProX (573-334-5439). They can explain the above also. Since you are from Kentucky, they could ship you one in a couple of days.

 

To answer your first question, yes an '86 cylinder can be bored over .040". An '86 cylinder can go to .120" but the '87 - '89 cylinders can only go to .080" before resleeving is necessary. Wiseco pistons:

http://www.carbidesmotoworld.com/cgi...wisecoatv.html
Note all the different sizes for the '86 cylinder as opposed to the '87 - '89.

Here's another site:
http://www.moto-man.com/cgi-bin/mtm/search?uIcP3MFR;;3

Pro X is another good choice but I don't believe they offer a piston for the '86 cylinder, just the '87 - '89.

 

Cool, thanks for the info. This is for a friend of mine who shattered his bottom skirt on the cylinder somehow. But he's got a spare one he came across a while ago. It's punched .080 over, and needs a fresh bore. I know what your talking about with the windowed pistons and the cutaway. My 400 Sport uses a window, while the 89 LT250R I'm building has a cutaway. I'll take that into consideration when I shop for my lt250r piston.

 

i run pro-x.

 

BTW, you can bore a stock 86 cylinder to .140.
Weisco makes pistons for all these sizes.
The 86 piston is different from the 87-89, the wrist pin is located 5mm lower in the piston due to the 5mm shorter rod. The 86 doesn't have a window, it has a cut-away.

 

Trapperb1 are U sure it can go .140.I always thought .120 for the 86's.Yes the 87-89's can only go .080.

I am not questioning U I just wanted to know for sure.No reason just want to know All I can.

 

I'm sure. I got one out in the garage. It's thrashed and needs sleeving, so now it's a paperweight.