426 rebuild??

3 replies to this topic
  • Tim

Posted May 30, 2000 - 05:34 AM


Hey boys,
Have any of you guys rebuilt your 426 yet? Or maybe even 400? I am sure somebody has so far....... How was it? Pain in the a$$? Do we have one of those "Plated Cylinders" or the good ole cast iron sleeve? Helping a buddy of mine rebuild his '99 KX 250 is creating a dark spot in my heard towards those "plated juggs". One more thing, how often do you guys replace the pistons, when you do replace them? Just rings?
Thanks in advance

  • Matt_Porritt

Posted May 30, 2000 - 03:00 PM


Rebuild a 426??
I know of many 98 WRs and YZs on stock piston and rings!
Cylindersare Plated
I've heard thad because the skirts are so short on the piston and rone to cracking it is better to replace both piston and rings instead of just rings.

**Ride it like you Stole it!**
Matt Porritt
99 YZ400F
Rubber Chicken Racing

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  • Ken

Posted May 30, 2000 - 04:07 PM


I put in a new piston and rings after about a year on my '98 YZ. Not a great deal of hours, but wanted to look for future reference. My feeling is that it was nowhere near needing changed. Everything looked as new.

Biggest pain was socket clearance on the camshaft cap bolts. I ended up chucking a socket in a lathe and turning down the wall thickness to get on a couple of the bolts. Torque wrench clearance a little tight in a couple places as well (with engine in frame).

I believe that there's been a post on it, but make sure the cam chain down around the sprocket on the crank is in order before reinstalling the cams / chain guides.

All in all, pretty straight forward, manual is pretty good for this procedure.


  • Tim

Posted May 31, 2000 - 06:09 AM


Thanks guys.

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