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350TSS · 07-12-2019, 02:14 PM

As I will be lapping the valves in and using some fancy American square section closer valve shim retainers all the valve clearances and the required shims will change when I come to re-assemble the head, nevertheless I thought before I disassembled it I ought to measure the valve clearances (and everything else that I have the equipment to measure) as it last ran.
As I disassembled it I was struck by what a clever design the head, camshaft and valve adjustment really is. I suspect doing valve adjustment on the bike would be an absolute pain and the thought of the valve dropping or the little wire clips dropping into the cam box would be a night mare. With the heads off and on the bench it is not difficult. All you need is a micrometer, a decent set of feeler gauges and a prong to hook the spring out with and a magnet to catch the valve retaining clips
Both the valve opener clearances were in tolerance (one bang in the middle and the other towards the upper limit) but both the closer clearances were much too large, (about the same as the opener clearances). Because of this, I was expecting the exhaust valves to show some sign of burned seats or pocked valves where they are supposed to touch the seat.
I was pleasantly surprised to find both inlet and exhaust in very good condition, very minor pocking, the valve stems were also bang on tolerance.
Not willing to take the barrel off so my measurement of piston clearance was only from the crown to the top piston ring and the gap was right at the close end of the tolerance in the Haynes manual (so virtually no wear).
The only component showing wear that I should probably do something about is the sleeve that runs inside the camshaft oil seal which has a discernible indentation where the lip of the seal runs. Easy I thought turn it round so the seal runs on a different part of the sleeve, but it only fits one way over the taper that holds the drive pulley. I will buy a new seal and when I replace it I shall put a o.5mm shim behind the seal so it moves the wear position to a new location on the sleeve.
Today was spent decarbonising the valves and the head and while I was at it I polished the exhaust port as best as I was able. I wanted to lap the valves in and start the process of getting the right shims in place. About 50 years ago I bought some valve grinding paste to lap the valves in on my 1948 G80 Matchless when I converted it to an aluminium head. I have used it maybe 10 times since and I have moved maybe 6 times and that pot has been faithfully transported to each new location. I know I have seen it where I live now but I could not find it. So that stumped further progress.

07-12-2019, 02:14 PM	#1042
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,419	As I will be lapping the valves in and using some fancy American square section closer valve shim retainers all the valve clearances and the required shims will change when I come to re-assemble the head, nevertheless I thought before I disassembled it I ought to measure the valve clearances (and everything else that I have the equipment to measure) as it last ran. As I disassembled it I was struck by what a clever design the head, camshaft and valve adjustment really is. I suspect doing valve adjustment on the bike would be an absolute pain and the thought of the valve dropping or the little wire clips dropping into the cam box would be a night mare. With the heads off and on the bench it is not difficult. All you need is a micrometer, a decent set of feeler gauges and a prong to hook the spring out with and a magnet to catch the valve retaining clips Both the valve opener clearances were in tolerance (one bang in the middle and the other towards the upper limit) but both the closer clearances were much too large, (about the same as the opener clearances). Because of this, I was expecting the exhaust valves to show some sign of burned seats or pocked valves where they are supposed to touch the seat. I was pleasantly surprised to find both inlet and exhaust in very good condition, very minor pocking, the valve stems were also bang on tolerance. Not willing to take the barrel off so my measurement of piston clearance was only from the crown to the top piston ring and the gap was right at the close end of the tolerance in the Haynes manual (so virtually no wear). The only component showing wear that I should probably do something about is the sleeve that runs inside the camshaft oil seal which has a discernible indentation where the lip of the seal runs. Easy I thought turn it round so the seal runs on a different part of the sleeve, but it only fits one way over the taper that holds the drive pulley. I will buy a new seal and when I replace it I shall put a o.5mm shim behind the seal so it moves the wear position to a new location on the sleeve. Today was spent decarbonising the valves and the head and while I was at it I polished the exhaust port as best as I was able. I wanted to lap the valves in and start the process of getting the right shims in place. About 50 years ago I bought some valve grinding paste to lap the valves in on my 1948 G80 Matchless when I converted it to an aluminium head. I have used it maybe 10 times since and I have moved maybe 6 times and that pot has been faithfully transported to each new location. I know I have seen it where I live now but I could not find it. So that stumped further progress.