Another newbie question...WR400 engine rattle

Ok, so I'm a new owner of a low hour 2000 WR400 and I need to know...what's up with that engine rattle? Is that normal? The guy I bought it from said it's "always" been like that. Did I buy a POS? I'm sure this has NEVER been discussed before (yea right). Help

My new 426 (dealer had a new one) has what might be called an engine rattle. Could be the cam chain noise I guess. With my XR400 if it sounded like my 426, it would need a valve adjust.

It's completely normal for a 400..

Bonzai :)

Is the rattle more noticable under hard acceleration from low RPM? - ie. lugging the engine, one gear too high.

Peace Eh - P.Z.

RockDawg. There was a problem with the key on the balancer gear. It developed slop and starts to break off teeth on the drive gear from the crank. In front of the crank and to the top of the motor there is a shaft that runs parallel to the crank. On the ignition side of the bike there is a balancer and this shaft also drives the water pump. The keyway that holds the crank gear in place has slop in some machines. In turn it breaks teeth off of the gear on the shaft. It starts to develop a knock every revoulution. It's a knock knock sound. A light rattling sound is normal, however you should have to hold your head down close to the motor to hear it.

My 400 has always had a little rattle noise at idle.

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