The only good things that has happened to my machine lately is that my left hand exhaust will not rust out as the inside of the tailpipe has a beautiful coating of oil. The good part is the exhaust from the right hand cylinders is ok. The motor at idle shakes more than a Harley. Does not sound good at all Any ideas what the damage may be?

Thanks

do a compression check sounds like rings or a cracked piston should be at least 90psi per cyl