Does anyone have a recommendation on oil? I have used Belray Exp, but wonder if something better exists. I just replaced the piston and cylinder. The cylinder was dimensionally correct except for grooves on the top and bottom from the rings, probably caused when the piston changed directions. The bike was smoking excessively at start up and compression was fading. BUT NOW IT RUNS LIKE A CHAMP. I would like to know some opinions on the best oil to prevent wear and not jag up the clutch.