February 16th, 2017, 02:47 AM
Joined: Nov 2001
From: Ely, England
the 450s are dropping the heads off the exhausdt valves or the single valve springs are breaking. peple cheapskate and fit only one new exhaust valve and so the other head falls off! it is the fault of the "percussion" from the single valve springs and only happens to the 450. not even one 550 or 650 so it is revs related as well.
not to say it is this but so that others change their exhaust valves and their springs soon enough. I have two blown 450 ewngines here now and what with some liner and jetting troubles I am sick 'n tired at the mo with 450s....
I'll get over it....