I have a Yamaha Scooter, after many engine rebuilds I put expensive Castrol, Fully Synthetic Oil in. The engine again, needs a rebuild, and it has barely done 1000 miles since the last rebuild, about 4 months ago. The man in the shop says there is carbon residue in the Cylinder which has scratched the barrel, causing the compression to drop. He says it's the 2 stroke oil, but it's the best I can find, fully synthetic, Castrol Power1. The bike needs JASO-FC oil or above, I have been using JASO-FD. Does anyone know of anything else that could be causing these problems aside from oil? It's getting rather expensive now. This will be the 4th rebuild in 2 years, the 2 of them were last year, just 6 months apart, and the last one was barely 4 months ago. Thanks.
It has been to two separate garages for the rebuilds and they both say the same thing.
