Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: 2STROKEREVOLUTION on October 12, 2012, 12:37:40 AM

Title: Top End rebuild - Oversize piston?
Post by: 2STROKEREVOLUTION on October 12, 2012, 12:37:40 AM

I have countless hours on my KTM 380SX. I am going to go through my engine soon and want to do it right.

My plan is to get a Wiseco piston. They are around $200. OEM is ~$300. Wossner is similar to Wiseco but is a single ring piston. Wiseco is also by far the easiest to install, the OEM is a pia, and the Wossner between.

Wiseco offers both stock bore (78mm) and 1mm overbore (79mm). That brings displacement from 368cc to 373cc. I am not looking for extra power from the minor displacement.

The Questions:
If I go to overbore, I expect I will have to have the cylinder honed to size, will I ever be able to go back to stock displacement without a steel sleeve?
Can I overbore/hone to that without needing to re-plate? Or will the nikasil be too thin?

Title: Top End rebuild - Oversize piston?
Post by: factoryX on October 12, 2012, 12:58:15 AM

I don't you can bore out a nikasil liner..

Title: Top End rebuild - Oversize piston?
Post by: scotty dog on October 12, 2012, 02:29:06 AM

Once you go over you can't go back without getting a new sleeve, I would say it has a nikasil cylinder so you can't go oversize anyway, unless you fit a steel sleeve

Title: Top End rebuild - Oversize piston?
Post by: 2STROKEREVOLUTION on October 13, 2012, 01:43:06 AM

Quote from: scotty dog on October 12, 2012, 09:29:06 AM

Once you go over you can't go back without getting a new sleeve, I would say it has a nikasil cylinder so you can't go oversize anyway, unless you fit a steel sleeve

Well you can overbore it, you would just have to re-plate it after. That's what my concern is. I don't know how thick the nikasil is to know if I can overbore that much without having to re-plate.