Registered Forum User
Big Twin
Bikes: Ducati 749, Phil Read Replica, DD 620
Posts: 1,830
Join Date: Mar 2008
Location: Coventry
Mood: 2011 DD Class 'B' Champion
Valve stem seal problems usually exhibit themselves on startup. Oil trapped in the upper chamber can leak down onto the top of the piston, resulting in smoke at startup.
Smoke whilst running usually indicates rings, Nicasil bores are very cruel to rings and you can end up with almost 3mm ring gap instead of 0.3mm.