I recently completed the A35 transplant on my '84 Silver Bullet and the bike is unbelievably fast now. The problem is that there is a metal clanking noise coming from the gearbox. It sounds a lot like chain slap, but it's not. The clanking is most noticeable at idle and goes away as the speed increases. If I hold the rear brake at idle, it is pretty loud.
I removed the gearbox cover and found some small metal shavings inside. The previous owner of the ped that this motor came from, had dropped the bike and dented the gearbox cover somewhat (but not that bad). I did notice some slight rub marks in the metal near the dented area inside the case cover. When I place my hand over the gearbox case cover at idle, the noise gets somewhat muffled.
This ped otherwise starts fine and accelerates like no other ped that I have ever owned. What could be the cause of the clanking?