Engine Rebuild

2 replies to this topic
  • FlyGi

Posted April 23, 2001 - 11:01 AM


I posted a while back and I've decided to completely rebuild my 99 WR. It has about 4000 (hard) miles on it, the engine makes noise and lacks power badly. I'm getting the frame powder sprayed this week and the engine done next week. It's also going on a weight loss program.

I'm looking for suggestions/experienences from people who have rebuilt their engines. I was thinking:

1. Top end (valves, seats, cam chain, tensioner)
2. Piston, rings and lower crank bearing.
3. Clutch
4. 2nd gear.

I'm trying to avoid boring the head.

Any other suggestions?

Canadians ride hard too.

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  • MN_Kevin

Posted April 23, 2001 - 11:18 AM


Valves and seats ground/replaced,
New piston, rings, small end bearing IF YOUR CYLINDER FALLS WITHIN SPECS!!!,
New cam chain,
Replace cam chain guide/rubbing block (2),
Clutch plates only if it needs them (is it slipping?),
For each speed gear, i.e. second gear, THERE ARE TWO GEARS. I'd replace both of them. The transmission shafts ride on bearings. It may behoove you to replace those as well. You do realize you are talking bucks here...right?
Eric Gorr does a 420 kit for $350.00 (U.S.) that includes everything you'll need, including the bore and re-coat. I think the piston kit alone is ~$200. Maybe something to think about. Clark Mason went this route, but he is also used to working on F-15
turbine engines. He likes LOTS AND LOTS OF THRUST. Did I say LOTS?

'99 WZ with all YZ mods, de-octopused, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, forked over by Pro-Action, OEM YZ tank, IMS YZ seat, carb mods by Jim Dean and Sir "Taffy" from Jolly Old England, AMA, NESC.

  • YZ400Court

Posted April 23, 2001 - 01:13 PM


Replace the rod, not just the bearing.
Let me say that again
Replace the rod, not just the bearing.
Okay one more time
Replace the rod, not just the bearing.

Everything on your list seems resonable. The rod is the weak link in the engine. If you have time call stroker and speak with the mechanic about it. He'll be honest, not just try to sell stroker parts to you.

Pretend it's flat and give it the gas.


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