Gentlemen,
I just opened a 650SS engine because of excessive oil smoke. I found that a previous owner has installed larger inlet valves (38mm) which apparently are from a Norton Atlas. According to spec the Atlas valve stem (part no. 06.7884 or V240 - is it the same valve?) should measure 5/16" (7,94 mm), but the stems of the valves installed only measure 7,88 mm and sit quite loose in the valve guide. I assumed that stems and guides are worn and that oil gets sucked into the combustion chamber because of this. OK, so I installed new Atlas inlet valve guides and ordered new Atlas inlet valves. To my surprise the brand new valves (G&S, Made in England) also measure only 7,88 mm stem diameter. Unfortunately I could not get a reply from the seller yet. I am puzzled - where is the mistake? Are there different versions of the same valve? 6/100 mm difference is more than the wear tolerance...
I just opened a 650SS engine because of excessive oil smoke. I found that a previous owner has installed larger inlet valves (38mm) which apparently are from a Norton Atlas. According to spec the Atlas valve stem (part no. 06.7884 or V240 - is it the same valve?) should measure 5/16" (7,94 mm), but the stems of the valves installed only measure 7,88 mm and sit quite loose in the valve guide. I assumed that stems and guides are worn and that oil gets sucked into the combustion chamber because of this. OK, so I installed new Atlas inlet valve guides and ordered new Atlas inlet valves. To my surprise the brand new valves (G&S, Made in England) also measure only 7,88 mm stem diameter. Unfortunately I could not get a reply from the seller yet. I am puzzled - where is the mistake? Are there different versions of the same valve? 6/100 mm difference is more than the wear tolerance...
