Join Date: Oct 2016
Location: ojibwe gichigami
Thanked 31 Times in 28 Posts
With 6600 miles on the sled it probably needs a freshening of both of the clutches AND the motor. In other words, fixing a single knocking problem at this point isn't likely to get you very far.
Start at the top end on the motor... you can plan on a fresh honing, putting new pistons, rings, wrist pins, upper rod bearings, circlips and gaskets in it, at the minimum. The lower end may need new crank seals at a minimum. Bearings too, or possibly worse... but you gotta get down there before you'll know for sure.
Pull the heads and cylinders for upper end inspection and go from there.
As for the clutches, they will probably both need to be completely rebuilt unless they have been well maintained and/or recently freshened. Look for cracks developing on your primary sheaves and replace the clutch if you find any.
Let us know what you find,