I did a top end on a 450 es last year. It had been smoking pretty bad for awhile. It fouled a couple of spark plugs. One night it just quit. New plug didn't help, it would not sty running. So it was top end time. It was just excessive wear in the cylinder. The bike had alot of hours on it when he bought it. And I dont thing the last owner did much maintenance like changing the oil and such. Anyways first size over, new piston, rings, valve seals and gasket set from wiseco and the bike has run like a top ever since.
Basically it had smoked itself to death.
Basically it had smoked itself to death.