KDXRIDER.NET

Hey guys,

Today i had my 1993 kdx200 scuff a piston. As soon as it quit i checked the cylinder to see how hot it was and it was warm but not ripping hot. When i got home i checked the spark plug and it was a beautiful beige color so i knew it was burning good. I then took off the exhaust and found the piston was scuffed. I know it wasn't lean and it wasn't heat, so what could it have been???? Note that it is the original engine, could it just be wear and a ring broke?

Thanks

Whats the ratio of oil used? Brand ? A pic with cylinder off may help.

I was useing Castrol super 2 stroke oil mixing at 40:1.... I had put about a tank of gas with different oil through it the day before at 40:1 and it was working great. tommorow im taking it apart so i'll post pics. Also what's a recommended aftermarket piston?

thanks

Thats enough oil so maybe someone had it lean before you and damage was done. Now may just have failed. I like Wossner pistons. Forged and coated to help stop scuffing. About the same money as wiseco. Just make sure you warm bike up before you let her rip.

http://www.wossnerpistons.com/products/ ... 66-mm-bore

How well was the exhaust sealed?

I noticed that one of the springs were missing from the exhaust but still it wasn't running lean...... ordered new piston,rings, and gasket kit for 150$ from my local kawasaki dealer, not bad.

On a 2-cycle the exhaust goes two ways. It is how the addition of an expansion chamber causes a supercharging effect. If your exhaust is leaking the cylinder can and will suck air on the exhaust side. Run the engine with nothing on the exhaust snout, and it'll burn up...fast.

http://www.vf750fd.com/blurbs/stroke.html

Looks to me like a few pieces of grit made it past the filter and nothing more. I wouldn't call that lean, burning down, lack of lube, or anything of the like. Just a little scratching from foriegn debris. Yea you don't want that, but it doesn't look like anything I'd lose sleep over. Make sure the filter is installed correctly and everything is sealed up good and keep on riding.

Turns out the Powervalve system was not put on correctly by the guy before me and they weren't opening or closing. There was a little curclip missing on the rod that opens and closes the powervalves which caused it not to move at all. The cylinder had some aluminum buildup on it and is at a machine shop right now being fixed. Should be back up and running mid next week.