Top end rebuild...

[Woll]

The cage around my reeds broke so i've decided it's time for a frsh top end. I cant find a workshop manual for mine (ec250 '98) so i've got a few questions.
How does the powervalve come out? I've removed part of it out of the left hand side of the engine, but i cant seem to get it to come out of the right hand side of it.
Another problem i've found is no letter stamp on the engine anywhere. Just measure the piston in and the cylinder? What should the clearances be?
Is there anywhere online that i can order the top end parts and re3eds from?
ta

 

[biggstr6]

I can't help with the other, but the letter should be down low on the cylinder on the carb side.

 

[Woll]

i've checked and double checked. The letter stamp isn't on there.
Had a thought before, the earliest workshop manual i can find is '03 does that use the same engine as the '98?

 

[stainlesscycle]

my 99 cylinder has no stamp either. i've not had it apart in a while - was planning on buying a backup top end kit, but not sure which one to get.....

98 is counterbalancer right? it's very similar to 03 aside from cb. - the workshop manual should get you close...

are you trying to remove the pv flapper? it does come out of the exhaust... just takes a bncha finagling.

 

[egesledder]

My 99 also had no stamp on it, although its best to measure your bore anyway when selecting a new piston.

PV Removal:

http://www.gasgasrider.org/pv_disassembly_mattr.pdf

 

[Woll]

Got some strange sizes here... i've measured the cylinder & piston with my vernier and me mates double checked with his vernier. The cylinder is 66.11mm and the piston is 65.89.... 300 engine possibly?

 

[stainlesscycle]

250 should be 66.4mm i believe, 300 is 72mm

 

[Woll]

well im baffled then... think i might go see gas gas uk

 

[Woll]

It's a wiseco s14ps... according to several websites it's a cr250 standard piston

 

[noobi]

Early engines were very similar to the CR250, so to me its not really surprising that there is a CR piston in there. Good news is, CR pistons aren't hard to find
Considering its ~12 years old its probably due for a replate as well as a piston.

 

[gasgasman]

On my '98 bike, the piston size(letter) was stamped on the cylinder left front of the exhaust port at the base.

 

[rgranger]

...'cause that will never change, so you want it in a place where you can easily find it rebuild after rebuild! Just don't get me started on the quick change air-filter