posted this at Cannondaleriders.com

Stud Update Explained

If the "stud update kit" is not installed, the bolts of the crankshaft catridge plate can loosen - eventually. Make sure its installed; if it isn't do it or carry a tow rope and a box of Kleenex. Removing and reinstalling the old bolts with loctite IS NOT ENOUGH. Why is the "update" needed? Well aside from the engine blowing up without a warranty to cover it, there are many reasons. (1) The crankcase design a big aluminum Slushie cup; it flexes (distorts) enough to when hot and running to loosen the bolts. Think about it. This puppy moves and then the plates move, and then the bolts loosen, and then they come loose and then the gears eat them. The more you jostle the cup (high rpm and engine loads) the more the cup mouth distorts. Mystery solved. The crankcase is very SOFT metal. heat, vibration and bad design all gang up at once. Had the case been made of steel the design might work, but its not so its got to be glued together = update kit. Check your cranks as well. Try balancing the crank. An unbalance crank couped with the loads created by combustion in a soft poorly designed case accelerate the problem. Some motors have a balanced crank, some do not. Look for a welded plug on the larger counter weight, if a weld is there the crank was corrected at the factory. The stud update kit only slightly increases the torque that can be applied to the plate bolts and slightly increases the compression area of the fastner since the nuts used with the studs are slightly larger.

Good luck!