Rattling noise In 400ex motor?

[Dicestyle1912]

I have a 03 400ex and when you rev it up, something rattles really bad. At first i thought it was something loose outside the motor. I couldn.t find it. I then realized it was internal. It is getting worse. What it is?

[motox92]

Valve? cam chain?

[JParisi48]

i think its your valves, my 300ex did that, u need to adjust them, mine was REALLY bad...after they were adjusted, they still rattled but not as bad...

[n811]

R you positive that you checked all other outside possibilities? I had a fender mounting bolt that would make this awful noise when I reved up that sounded like the motor was bad. It was touching the frame and resonated through the whole bike. But you should check your valves at least twice a season minimum.

[dukee66]

its ur valves or cam chain needs to be tightend

[rob_990]

the chain tightens itself only to a certain point then you have to replace it. theyres no way of just tightening it like the chain outside the motor.

[RaceinCircles]

If you have a bolt break in your header where your heat shield is, it will have a rattle...just a little checker before you tear in.

[Rastus]

Use the KISS method.


If nothing comes up on the outside, it sounds like a cam chain to me.