My scrambler 400 makes a loud clunking noise when it is under a load, if you let off the throttle it stops give it gas and its back? Chain and sprockets look fine and so does the belt? This is relly baffleing.

 

The silent chain inside the gearcase sounds like that

 

MY PRIMARY CLUTCH IS VERY SLIGHTLY TAPPING THE COVER,SOUNDS LIKE A HOLLOW THUDDING (WHAT THE ) I GRAB THE BELT COVER BELOW+PULL IN+OUT WHILE HITTING THE GAS ALITTLE + IT GOES AWAY+GETS WORST.

 

This only happens when riding it, I lifted the rearend off the ground with a hoist and gave it gas but it wouldnt do it. But as soon as I put it back on the ground and rode it, it was back. Its also losing power do to whatever this is. Silent chain?

 

Have you checked and lubed your rear drive chain?? I had mine acting up and cleaned, tightened the chain and all was better!! Just a thought...

 

Pull your secondary clutch apart and check the buttons before jumping to the tranny.When you said it was loosing power this could the problem

 

i have an i dea your rear axle bearing can be bad and your right sied of the axle moves forward under load and the sprocket on the axle hits the swing arm that happend with mine once jack it up and see if the axle has play in the swingarm of not

 

are any of your cv boots ripped? kinda sounds like your cv joint is going out...............shea................

 

I'd go with what ftwflh says

 

there isn't any cv boots on the scramblers but i forgot about the front my scrambler is a 2/4 yea the fronts could have problems because the shafts spin if it is in 4 /4 or 2/4 becaus it engages at teh hub