This afternoon I was changing oil in my 2006 Yamaha YZ450F and I noticed eight steel ball bearings on my magnetic drain plug! The balls are less than 1.6 millimeters in diameter and look like differential balls out of a mini bike. I can't figure out where they came from. I started the bike and it sounded fine. Any ideas?
We asked a Yamaha expert and he was amazed that you were brave enough to start the engine, what if there was a ninth ball bearing?
The only place those ball bearings could have come from is the â€œshift drum detent.â€ It is the only part of a YZ250 that has small bearings in it. We suggest that you look there first. And, since the balls are contained in a cage â€“ the expert assume that pieces of the cage must be in the engine also.