Piston identification

[2004ec200]

Hi all,

I'm freshening up the top end on my 200. The piston that came out has the following numbers stamped in the top:

D01k0
7711
62.46mm

Any one know what kind this is?? Stock?? internet search turns up nothing. Size matches the 'B' stamped on my cylinder.

Cheers,

Tom

[barossi73]

post a pic,someone might know.yesterday i posted pics of a 200 vertex,and a wossner(both A)in the 2stroke eng forum.the vertex s3 was stock,the wossner went in my 13.what year is your bike?the A,B,C size diff is so small its largely irrrelevant,just dont go smaller than your barrel.id put a B in if the bore is fairly fresh,and a C if higher hrs.be careful on higher hr barrels if you change the base gasket(drop barrel) the top ring could pick up on any wear lip at the top of barrel as well as increasing compression and poss the chance of detonation!if the bike ran fine before put the exact same base gasket thickness in.the wossner A i put in is listed as gg ec200 03-09 dia.62.45mm.weirdly the B was $50 more than the A or C?also once you get the new piston use the wrist pin to join the old/new and check the crown profile matches.the wristpin needle bearing should be cr250/yz250.compare bearing width.based on your piston spec the diff between A and B is 0.05mm or approx 1/33 of a flyshit!

[gasgasxc]

Can you see anything on the inside of the piston.Up inside stamped in the wrist pin boss.A small W maybe.Those numbers look Wiseco to me.May be a Wiseco B piston.

[2004ec200]

Thank for the info. bike is a 2004 ec200. I don't think its a Wiseco, they don't offer different sized pistons for gasgas that I can find. There are no markings on the underside of the piston. I have a Wossner on its way. Bike ran great before tear down. 165psi compression. Don't know when the top end was last serviced so since I have the rear shock off being serviced and figured I'd freshen up the motor.

Squish measured 1.5mm. By what I remember 1.0 to 1.4 is optimum for a 200 so I thought about a thinner gasket but didn't think about the ring getting into the wear lip. You gave me something to think about. I'll check the squish when putting it back together with the same size gasket that was it there (0.3mm green gasket) and go from there. I guess I'll also measure ring placement on new piston vs old. Don't know if it would be different but I guess I'll find out.

Cheers

[gasgasxc]

While youve been piston hunting did you find any cast pistons available for the bike?

[2004ec200]

While youve been piston hunting did you find any cast pistons available for the bike?

not for a 200

[Rick]

My guess is a Weisco......here is one that came out of my 99EC 200.

If I'm not mistaken a Polaris sled that uses the same exact piston as the GG 200, the pistons for that sled come in oversized.

The confusing part is, the box label say on size and the lid of the box is label another. I'm certain I have a b cylinder with an oversized piston from Weisco in my bike now.

The bag is the part number for the rings.