Back end hits when i throttle or hit the brakes hard. Any idea? 81xj650 Maxim H.

I have rebuilt my bike from the frame up and finally got to do a test ride. When I give it gas or hit the brake i feel the back of the bike makes a clunk noise. like something is slamming when I hit gas or brake. Any idea?

 

Did you fill the final drive unit with the right amount of oil?

 

Yep Sure did. I topped it till it poured out. any other ideas?

 

It's likely the cam in the middle drive gear. That part acts like a cush drive. A bit of noise from it is normal, but you should also check the u-joint on the driveshaft for wear, and make sure all of the fasteners in the rear of the machine are torqued correctly.

 

Thanks. I'd hate to tear the motor back open. did that once already. I will double-check the U-joint for wear and for the right torque spec.

 

got it cool I just looked it up. Not a engine tear down. I can work with that. Back end not so big a deal. Thanks for the tip. I will look at it later.

 

It is acting like the springs in a car friction plate, the springs absorbing the torque from the combustion strokes.

 

Yes, it's similar. The middle gear cam is really absorbing the shock load from sudden applicatons of torque that don't quite exceed the grip of the rear tire. It saves a lot of wear and tear on the u-joint and geartrain.

 

My 650 Maxim does the same thing, clunking if I brake hard or hammer the throttle. Was concerning at first but once you realize how the middle drive is set up it makes sense.

 

I had a similar issue but it was exhaust rubbing over axle castle nut.