great to be back on a gasser, but need a piston!
 

Hi guys not been around for a while, bit of background:- Back in 2009 I had another excursion over to the dark side that is the Yamaha WR250F ali frame...heavy old lump, that never any inspired confidence, my steel frame WR250F version was a better bike looking back!

Sold that old WR tub 3 years ago, now into trials but also getting back into enduro and sense prevailed and bought another gasser, an '08 EC250.

Previously I've owned two EC200's before, '06 and '07 and I've gotta say this 250 has a lot more hit even in rain mode....bit too much for me at the moment even with the Gnarly pipe....pulls well down low but doesn't low rev' 'chuggle' thru the tough stuff like my 200 did. Jetting is gasgas as the manuals competition recommendation and works fine...170 main 38 pilot and erm....something F needle..NE1-F?...I'll check that.

Anyway complete chassis strip down last week and raced her yesterday, I'm 50 now, bad pancreas (don't drink now though) and unfit, , but was it always this tough:eek: I was shattered after 20 mins.


.....anyway she handled great, pulled me through and no offs so everyones happy.

....but one thing is on my mind, I think she really does a new piston, quite a bit of piston slap, well a lot really. I find this a little strange as she has done but 59 hours use, and I only found some slightly rusty headset bearings, everything else was fine so no reason to doubt this and she is superclean all over. But, my older 200's did 2 seasons hard racing, really tough trips to Wales, lots of trail work and ran sweet as with way, way more hours...I NEVER had the engine to pieces on either...but both bought as new when a few weeks old and I always treated them to good oil and clean air after every ride.

I've had a look thru both inlet and exhaust ports and to be honest there isn't much blowby at all, but another thing is that leads me to suspect the top end is that she is a little reluctant to idle (I know it's a gasser) and I suspect she is a little down on compression...she has an easy kickstart action compared to my Beta REV3, maybe a bit unfair being a high comp trials bike.

Whats the word of Wossner pistons, which is what my local supplier sells or go genuine.

....before anyone asks, no slack in power valve, I've preloaded that Saturday and no difference!

cheers guys

I wouldn't hesitate to use a Wossner piston...and have used 2 of them.

I would run a compression test before tearing it down.

My bike had a good rattle and turns out it's the exhaust orings are worn out. It lets the pipe vibrate around and it makes all kinds of noise. If your pipe slid off and back on easily without much resistance, you might want to replace them. Not saying that is what you are hearing but 59 hours isn't much for a too end on these bikes.

In my very brief history of gas gas/2 stroke experience, 250s tend to go shorter on hours for the top end. My 08 is certainly supportive of that theory with some big ring gap for the hours on it.

I put a Wossner kit in it which was very commonly used when I was doing research.

Cheers guys.....new o rings on exhaust stub....i wish it was that easy!

I'm going to strip her down and have a poke around, i'll chime back what i find...rather than risk a cracked piston.

Stripped her down today.....amazed at how well she ran with rings gaps of over..

....2mm!

A sized bore and original piston still, wossner on order.

Sounds familiar.

Ive just put one of those in mine ......

All done and dusted.....engine now quiet as can be.

wossner piston used, looks a nice bit of kit, great finishing.

cheers guys


off to the enduro park for the day!