Sleeve repair

Took my 99 400 apart over wekend and found minor vertical scratches on cylinder wall, exhaust side. Should I have a sleeve installed or should I just have the plating redone ( nikasil ? ) I heard that a cast iron sleeve may reduce performance. The scratching seems minor execpt for one which is about .015" wide by 3/16" long. I will install new pistin / rings and am considering a slightly higher compression ratio piston such a a Wiseco.( 13 : 1 ) Is there an advantage to this set-up and will it affect reliability? Thanks for your help!

clark mason has the 420 kit from eric gorr with the higher compression i believe. you might want to get his impressions first. if you have it apart, the cost to go with the big bore kit is about $300.00-400.00.

If you are not in a hurry (and don't live around Madison WI) you could send your cylinder to Eric Gorr and he will not charge you to look at it... and if it does need some work, he would be the man to talk to anyway.

Hope this helps


I was also going to advise Eric Gorr as someone to check out your cylinder. If you've changed your spark plug a couple of times and didn't blow air thru that little hole on the right side of the cylinder head, dirt and debris could have fallen inside the cylinder when you lifted the plug out. It's amazing just how much junk collects in that cavity.

[This message has been edited by Boit (edited 01-15-2001).]

Yeah, I know Boit. Bought the bike used and I think the previous owner did some sloppy track-side plug changes. There was enough grit in there to do some serious damage.

This seems to be an obvious but often overlooked fact with dramatic consequences. :) Anyhow the damage was done, will probably only have replated locally ( after precision honing / mesuring ) as a reputable rebuilder here in Montreal ( J. Precision Racing ) says that the wall thickness of Yamaha's nikesil may be as much as .010", thereby ridding the minor grooving that I have found. Should I use an original Yamaha piston or an aftermarket such as Wiseco or others?

[This message has been edited by Hugh LePage (edited 01-15-2001).]

[This message has been edited by Hugh LePage (edited 01-15-2001).]

Wiseco pistons are forged from a block of metal, so they are not always cut to exact sizes. They also may not be a perfct cylinder, so i would go with something else. I hear JE are good or White Brothers are the best. Good Luck.



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