engine noise

[jgbailey57]

I just recently acquired a 400ex and noticed it has a knock at idle. I thought it was the valve adjustment but it made no change when I adjusted them. The noise is coming from the top right side of the engine. I used the bar to ear trick to try to pinpoint the knock but was fairly unsuccessful. It was the loudest when I was on the right side exhaust pipe. It doesn't sound like it would be the timing chain making noise, it's more of a solid knock. I revved it up a little and the knock went faster along with the motor. Supposedly it's supposed to have a brand new piston in it. I had the valve adjustment covers off and started it to see if the noise was louder. It definitely sounds like it's inside the engine somewhere, it's not the rocker's ticking. Please tell me it's not a bad rod bearing. It runs great and has good power and throttle response. Well, what little I've ridden it. I'm waiting on a carrier and new bearings. Help me out guys, this thing is really making me kick myself for trading the Banshee.

[Castor-426ex]

well sounds like a timing chain is slapping around....especially from where youre saying the sound is coming from

[jgbailey57]

If it was the timing chain slapping around wouldn't the noise be a little erratic? This is a steady knock that changes only when the rpm's change.

[jgbailey57]

I just remembered, it has a really noticeable miss. It couldn't possibly be that the guy timed it wrong and the valves are hitting the piston could it? Maybe I have a bent valve?

[Castor-426ex]

hmmm
pull the head cover off and the timing covers on the left side case.....look at the index marks on the cam sprocket....when the sideways T lines up with the mark....then the index marks on the cam sprocket should have one line pointing up and the other two should be flush with the top of the head

well heres what it could be....jetting.....a rocker arm thats about to go...it could even be one of the rocker tappets....

is the motor stock?

you could have a cam bearing going out...rare though

the timing chain tensioner could have let loose and failed
and the chain would still slap like that

[jgbailey57]

Ok, I'll try to check it out tonight. Thanks for your help so far, I'll keep you posted. The motor is stock.