I’ve drained the oil out of my Aprilia RS125’s broken gearbox this afternoon and once I removed the drain plug I noticed small cylinder-shaped bits of metal stuck to the inside of the plug. Any ideas what on earth these could be? Are they the cause of its failure?
Michael Johnson, MCN forums
If they are like little rollers all the same size and shape I would suggest you have a roller bearing broken up within the gearbox or engine. Have a look at the schematic when you get a manual and see where in the box there is a set of roller bearings – that will point you in the right direction. There are plenty of downloadable workshop manuals on the web. Try this site.
There are several on there for the RS125, including one specifically for the Rotax engine. By the look of it there are about seven sets of roller bearings in your gearbox, but it doesn't look too hard to strip it down and have a look. I hope you sort it and get mobile again ready for the summer.