New member, permission to board

[Martin-EC300]

Hi, I'm Martin from Wales and I've joined as I need the help of the masses.. I've just pulled the piston from my 08 ec300 for ring maintenance.

Everything looked great internally till I noticed 2 cracks running either side of the piston!!

So my question is do I replace like for like or do I change the size by a fraction, my cylinder wall is perfect, no scoring, hot spots or any other sign of friction ... Below are this pics of the piston size and the damage... Many thanks in advance

 

[Zman]

Wow you got luck on this one!!! You need to measure the cylinder to be certain otherwise it is just a guess.

 

[Brian VT]

Welcome aboard.
You sure dodged a bullet there.
The consensus here seems to be that there isn't enough difference between the A, B, and C pistons to worry about. If you have the time and resources to determine which size will be absolutely perfect then go for it but I'm under the impression that any of them should be just fine.

 

[Martin-EC300]

Thanks for the quick responses, your right about getting lucky! The only reason I did this was because I was messing about with my sons CR85 and noticed he had more compression on the kick than the gasser. I originally put this down the the stroke of the CR kick start as its tiny, but it did get me thinking!!

Unfortunately I don't have a tool to measure the bore, I might ask my local bike shop if they have one tomorrow, ideally I'd like to get the bike back together by the weekend.

 

[Martin-EC300]

Well I think I've found all the info I need thanks to google (tapatalk as usual is useless)

 

[imsimon]

Welcome martin,

always nice to have some more people from the uk.

ive just put a new top end in my 250. I just went with a wossner piston and went for the same letter size printed on rear of the cylinder and so far all is good!

bet ure sons bike is a good laugh!

 

[Martin-EC300]

Yeah it's a riot, all chaos and noise.. Mental bike for such a small engine!

I've just ordered a wossner too

I just want to get it all back together before I forget how to.. It looks pretty sorry for itself at the moment.. As you can see I was already balls deep before pulling the head