I have a 1988 kx 250 there are two small patches where the nickel seal is flaking off, im wondering how long it will last like this or if I could bore it out and put an over sized piston in without getting it re nickel sealed? I can’t justify spending big money on a old bike.

matt kx250 said:

"nikasil" not nickel seal, it is a form of plating. how long it will last?... its already way past worn out, that is considered damage, not wear. you have 2 options; replate or sleeve the cylinder. both are about the same $, plating is far superior

You having or wanting to spend money is sadly not related to the mechanical condition of the cylinder. It needs to be replated.

KDXGarage said:

Dammit, KDXG- there you go again with that lame fact-based logic. Knock it off immediately- don't you know this is the interwebs?!

That cylinder is not plated with nicasil, Kawasaki didn't start using nicasil until 2003. All cylinders before then are hard-coated by an electrofusion process, whereby molybdenum is welded to the bore surface with multiple wire feeds and then machined to tolerances. Kawasaki's electrofusion plating is significanly softer and thinner than most nicasil plating, and is notoriously prone to chipping and peeling, as you have discovered.

Send the cylinder to one of the aftermarket re=plating companies, such as Millenium Technologies, and they will re-plate it with their own propietary nicasil formulation. The cylinder will come back better than new.

Ok thanks for the help, before I striped the engine down I could not get it to run any good while I was riding it. I tuned it to run a little rich then when I started to ride it would lean out and would not go into power band. I had the cover of the side and the power valve would rapidly come in and out at high idol. I thought it had a stuffed crank seal but after pulling it down that's not the case. any ideas?

I hear ya, porterdog. :)

matt kx250 said:

hhmmmm, maybe the peeling plating had something to do with it.