Bore oversize?

[2strokesrock]

I am looking at buying a top end from wiseco for my 1990 KDX 200. I have never done this before and I was wondering about bore oversize? is it needed? what is it for?

 

[mudpack]

I can't find a top end kit for the KDX200 in the Wiseco catalog
If you are talking about just a piston kit, then you need to mike your cylinder and find out which piston will give you the required clearance.

 

[glad2ride]

The stock cylinder is plated. You can't just run down to the local machine shop and have it overbored for $40 and slpa in a new piston and rings.

If the plating is not worn out, then the stock size piston and rings are used. If the plating is worn out, it needs to be replated.

A guy who posts on this site and has a jillion hours of experience (even for the World GP races!!) told me that the 1989 - 1994 KDX200 can not be overbored without losing the power valve system, since the valves are very close to the cylinder. I would suggest you leave it stock.

 

[julien_d]

A guy who posts on this site and has a jillion hours of experience (even for the World GP races!!) told me that the 1989 - 1994 KDX200 can not be overbored without losing the power valve system, since the valves are very close to the cylinder. I would suggest you leave it stock.

as far as I know this is correct. E series KDX200 can not be overbored due to no clearance on the powervalves. If the cylinder is in bad shape, you MUST have it replated and restored to stock size bore.

J.

 

[2strokesrock]

I don't want ot overbore unless I have to. ok then I will take it apart and see what size it is and what the plating looks like.
sorry I ment "piston kit"

thanks