Broken transmissions on 400/426?

About three months ago, the 2001 WR426 of my riding buddy blew up the transmission in a big way. Took out the cases, the piston, several gears and shafts in the tranny, and more. It had less than 1,000 miles on it. He got towed nearly 100 miles out of Baja by a red bike.

Last weekend, my WR400 transmission blew up, shifting from 3rd to 4th, gently, with the clutch. Terrible noises, and can't find neutral anymore. 40 mile tow back to the truck, behind another blue bike. I haven't had the engine taken apart yet, but there are small metal fragments in the oil and oil filter. At least I found no oil in the coolant that I drained, or coolant in the oil.

Searching these Yamaha forums for "transmission", I really don't find any reports of problems such as we have experienced. Are my buddy and I just really unlucky here, or are there a lot of unreported problems with these transmissions?

I'm starting to think the quest for light weight is affecting reliability and longevity.

Before i bought my 426 i hired a yz426, it had a dickie 5th gear thats all i have ever heard about transmission problems.

My '99 had a bent shift fork about a year ago that made 5th gear useless. I had to replace one shift fork and 2 gears. Other than that, the tranny has been reliable for me. On average, I have put about 100 hard miles on the bike every Sunday for the past 2-1/2 years.

My '01wr426 started popping out of 5th after 1400miles of baja and about 50dyno runs.

I am not complaining.

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