Known Problems of '99 YZ400?

3 replies to this topic
  • onecolumbyte

Posted July 05, 2006 - 11:58 AM


I just bought a '99 YZ 400F and was wondering what the "known issues" were for these bikes? I checked out motoman393's website and appreciated the great article about the chain slider and the "cheap" fork tools. I was also reading that us Yamaha guys better go out and grease the head bearings. Are the head bearings a common problem for Yamahas? What other things are known to cause problems for these bikes?

I've got a good idea on general maintenance (valve clearance, linkage greasing, oil changes etc.). I just want to know what Yamaha special issues I should be looking for.

  • PumpkinHumper

Posted July 05, 2006 - 06:24 PM


Not a lot. The 99 was a pretty bomb proof bike.

Ya might want to replace the timing chain. They have been known to stretch over time. They can jump timing if let go to far.

Other than that just keep up on the maintanance. I would change all the fluids. And I mean all the fluids. Brake, oil, coolant, fork and shock oil. Then go thru and lube up the linkage, brake pivot, kickstarter pivot, and steering bearings.

Might want to go thru and pull all the smaller bolts for things like controls, brakes, and body mounts and antisieze them all. It makes a big diff down the road.

Its a heavy bike but a pretty reliable one. I have flogged mine to death and it still runs strong. Enjoy it.

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  • onecolumbyte

Posted July 06, 2006 - 09:18 AM


Glad to hear they're tough! On the timing chain point. Could I check the autotensioner in some way that would tell me if the chain was streched? I've seen instructions on removing the tensioner but it seems that there should be a way I can check how far it's extened to tell if the timing chain is streched alot....

  • Jekel

Posted July 08, 2006 - 07:20 AM


My 99 WR is great. Put a grease jert in the steering head tube for a quick fix for bearings.

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