Options for rebuild- wr 426

4 replies to this topic
  • ndkirwin

Posted September 28, 2008 - 01:07 PM


My 2001 WR426 bit off a few valve heads and seized the piston to the cylinder. What do you think would be the best rebuild route? Buy a used 2000 WR 400 engine and install it in the bike? Buy a used 2000 YZ 426 and sell off the rest of the parts besides the engine and install the flywheel, etc off the WR for lighting on the bike? Or should I send the cylinder to be renikasiled and the crankshaft to be rebuilt with a new rod and get a used head? Any advice would be greatly appreciated.

  • xrmarty

Posted September 28, 2008 - 10:49 PM


It's up to you and how much money you want to spend. With buying a used motor you're taking a chance but it's much cheaper than rebuilding the entire motor.

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  • ncampion

Posted September 29, 2008 - 07:55 AM


Have a friend with the same problem. He found head and cylinder on ebay for around $400 and we did the entire rebuild for under $600. Runs like a new bike and should be reliable. I really don't like Ti valves for the very reason you are having problems.

  • ready fredy

Posted September 29, 2008 - 10:58 AM


As for me I would rebuild yours with the exception of the Ti valves, If you buy a used one theres a good chance its very tired thats why the bike is being parted out. Just get a used 40 head instead of the 426 coz it has stainless valves any way. But remember if you use a 400 cylinder you will have to use a 400 rod also because of the small end diameter or you would have to have the small end bronze bushed at least to use the 400 piston on a 426 rod. This way you know what you have and it will be fresh and good to go for years. Just be sure to clean all of the oil lines when you have it apart so you wont be pumping schrapnal in your new motor!!!

  • Birdy426

Posted September 30, 2008 - 09:39 PM


Go big bore! Luke's Racing kit is about 5 bills. How bad is the head? Engine Dynamics can work miracles...


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