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hey guys today i took apart my bike to replace the piston and turns out it has a 72mm piston in it! What's going on??

I've been doing some reading and see that it has a 240cc big bore kit. Where can i get a replacement piston??

thanks

66mm is the standard bore size for the 200 and 69mm for the 220. Largest wiseco offers is a +1.0mm 70mm piston for the 220 and +2.0mm 68mm for the 200.

So I assume the bike is running without power valves then. Does it have any bottom end power?

contact Eric Gorr at forward motion
he is the one who came up with this set up and he should be able to help you find a piston for it

http://www.eric-gorr.com/bbmasterlist.php

(for some reason he only has the 225 and 255 kits listed, might be a typo on the latter)



since the stock size is 66 and you are 6 MM over that I don't see why it wouldn't have powervalves?
all it takes is 3 MM of off the main valve to get proper clearance no?

Probably depends on which series/model it is. If I remember correctly Jason said that no bore is possible on the E series without removing the KIPS. With removed KIPS can be bored to 240cc.

could be, but I don't see why ?

if memory serves me well I have a 2 MM overbore in one of my KDX 200s and that did require a recutting of the main power valve
the good people at wiseco were kind enough to include instructions on tolerances with their 68MM piston

I had a closer look at the piston and it says: A75F9 on the top and in the middle says 8003 72.20mm. It has a W on the piston and it's forged so it leads me to beleive its a wiseco forged piston.

Try Kustom Kraft for a piston - they do 240 kits for the KDX.

http://kustom-kraft.com/KAWASAKIKITS.html

Cheers.

Gotanubike wrote:Probably depends on which series/model it is. If I remember correctly Jason said that no bore is possible on the E series without removing the KIPS. With removed KIPS can be bored to 240cc.

I spoke with Eric Gorr years ago on it.

Jason wrote:

Gotanubike wrote:Probably depends on which series/model it is. If I remember correctly Jason said that no bore is possible on the E series without removing the KIPS. With removed KIPS can be bored to 240cc.

I spoke with Eric Gorr years ago on it.

good enough for me then, I still don't understand it, but i'll accept it

Mine's a 1993 kdx240 and the KIPS system still works. I read that their is a mod that makes them useable with the big bore kit and i'm guessing i have that mod done to my cylinder.

WOW that's crazy....there is only about 2mm of cylinder wall behind the center valve. Any boring would surely clear out that part, leaving about a dime's diameter worth removed from above the main exhaust port.

I'm guessing a good portion of the larger displacement is through the stroke..

My understanding of the 240 kit on an E series is that you can keep the subvalves, but lose the center. Perhaps different shops have different methods, I don't know.

seanalex538, any chance you could post a few pics of your cylinder bore?

It has been 8 or 9 years since I called and asked him. I do remember something about (not enough material) or something like that.

One possible big bore option for the 1994 KDX is.....WAIT FOR IT.........

Hey guys,
My local machine shop can get Wossner pistons!!
I'm getting a 73mm forged piston with wristpin, c-clips, rings, for 150$ shipped!!
And how do you post pics???

Upload to a image host like photobucket.com and copy and paste the .jpg it gives you

http://s1295.photobucket.com/user/seana ... 7.jpg.html

http://i1295.photobucket.com/albums/b62 ... 5a6a60.jpg

http://s1295.photobucket.com/user/seana ... d.jpg.html

Theres a couple pics of the piston. The cylinder is at the machine shop right now but when i get it back i'll post pics

Seanalex538 i know this was a while ago but what did you ever find out about that 72mm piston because i just got one with a 71.95mm piston and cant figure it out