WR400 top end rebuild-question

6 replies to this topic
  • XR6's_rule

Posted April 15, 2002 - 11:04 PM


I'm rebuilding the gearbox in my WR400 after FIFTH GEAR FAILED. I'm also doing the top-end while I'm at it. I am installing new piston-rings. I have a question: seeing that the bore is nickelsil plated, should I (can I?) hone that bore so that the new rings can wear in properly?
Any help much appreciated..

  • MN_Kevin

Posted April 15, 2002 - 11:44 PM


One shop REFUSED informing me it would RUIN the Nikasil.

  • Snapper

Posted April 16, 2002 - 03:49 AM


My understanding is that Nikaseal can't be honed. Whilst it is pretty tough it is a coating only.

After dropping a ring on my WR250 Two stroke last year I had the barrel welded and re-coated by an Aus. Company called Electrosil (about $400 Aus).

Honing will mean it needs recoating.

It will only need honing/recoating if it has pretty serious marks in it.

Whilst my experiance unitl recenlty is with 2strokes, the barrels only need redoing when they are scratched. I put several pistons in the barrel before the ring tore it and it needed repairing.

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  • Ynahg

Posted April 16, 2002 - 04:55 AM


No honing needed (or allowed) just put in the new piston rings.

If you have no compression after your're finished (and the cam timing was done right) don't worry, had the same problem. Kick a few times, it will probably start and after that you will feel the compression = oil was sprayed on the cilinder wall.

Good luck

  • SFO

Posted April 16, 2002 - 08:05 AM


You can scuff the finish in the bore some with a scotchbrite 7447 pad to assist the rings in seating.
I got this directly from US chrome.

  • XR6's_rule

Posted April 16, 2002 - 11:32 PM


Many thanks for your help/opinions guys!! WR will be firing this w/end and I shall ride him and park XR6 down the back of the shed again!

  • Taffy

Posted April 17, 2002 - 01:37 AM


any crap alloy on the cylider wall should be removed using acid and a load of cotton buds.

my bottle leaked BTW. holy sugar! wicked stuff!



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