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350TSS · 10-12-2019, 09:28 PM

I then put the valve into the guide and pushed it into the completely closed position. I tried inserting an electrical screwdriver between the valve stem and the seal edge and then rotating the screwdriver (much like fitting a tyre) but with only about 120 degrees available to turn the screwdriver blade it never “caught” and never flopped into the groove. Eventually I had to resort to using the blade as a “snow plough” to force the outer edge downwards and to engage with the groove in the valve guide stem. The green seal on the inlet seems thinner and I managed to pierce the first one with the blade of the screwdriver, fortunately I had the gasket set additional spares.
I did the exhaust first, (the black seal) and after about an hour got it to seat properly.
The next job was to set the exhaust valve clearances.
First, I fitted the original opening and closing shims (valves had been ground which would have meant the stem was deeper in the cam box, whilst the fancy USA valve collets would in all probability move the top of the valve stem away from the cam box).
A long while ago I bought a complete set of valve shims in 0.10mm increments (0.039” in real money). With the old shims in place and the valves installed the valves clearances were in both cases exactly between the ideal setting and the next upper or lower size shim – double bugger!!!
Setting the opening shim was easy, with the retaining spring clip out of the way, the rocker could be pushed to one side, the camshaft jiggled to get the closed position and different size caps could be inserted and measured in a matter of seconds.
The closing shim was an entirely different matter, there are 2 methods of measurement, the handbook way and the CCW (California Cycle Works) way. The correct clearance on the closing shim is between 0.03mm and 0.05mm, (0.0015” in real money) basically sod all and shims that thick are a) extremely difficult to manipulate and b) virtually impossible to be accurate with when trying to insert them between the sides of a rotating shim collar and a forged fork with access to only one side which is subject to a moderate closing spring pressure.
I tried the Ducati manual method and got inconsistent results. The CCW way involves setting the opening shim and then measuring the opening shim gap with the closing shim fork pressed down with a screwdriver and subtracting the total clearance from the clearance with the closing rocker under closing spring pressure. I spent ages trying to get two results to add up - it was nevertheless more consistent than the Ducati manual method.
After 3 hours I had the opening clearance about 0.005 too tight and the closing clearance about 0,01 too loose. Much of this time was spent figure of eighting the shims on 600 grade wet and dry to reduce their thickness.
Part of the reason it took me three hours was I spent about an hour (on 3 separate occasions ) looking for my fancy USA collets which had ejected themselves past my face as they failed to engage properly as I released the tension on the closing shim.
All good fun- and I am sure I will get better at it with more practice.
PS I tested the exhaust valve by pouring methylated spirit down the exhaust port and it seals perfectly. – Result.

10-12-2019, 09:28 PM	#1046
350TSS Too much time on my hands member Join Date: Jan 2013 Location: Shipbourne Bike: M900 Posts: 1,419	I then put the valve into the guide and pushed it into the completely closed position. I tried inserting an electrical screwdriver between the valve stem and the seal edge and then rotating the screwdriver (much like fitting a tyre) but with only about 120 degrees available to turn the screwdriver blade it never “caught” and never flopped into the groove. Eventually I had to resort to using the blade as a “snow plough” to force the outer edge downwards and to engage with the groove in the valve guide stem. The green seal on the inlet seems thinner and I managed to pierce the first one with the blade of the screwdriver, fortunately I had the gasket set additional spares. I did the exhaust first, (the black seal) and after about an hour got it to seat properly. The next job was to set the exhaust valve clearances. First, I fitted the original opening and closing shims (valves had been ground which would have meant the stem was deeper in the cam box, whilst the fancy USA valve collets would in all probability move the top of the valve stem away from the cam box). A long while ago I bought a complete set of valve shims in 0.10mm increments (0.039” in real money). With the old shims in place and the valves installed the valves clearances were in both cases exactly between the ideal setting and the next upper or lower size shim – double bugger!!! Setting the opening shim was easy, with the retaining spring clip out of the way, the rocker could be pushed to one side, the camshaft jiggled to get the closed position and different size caps could be inserted and measured in a matter of seconds. The closing shim was an entirely different matter, there are 2 methods of measurement, the handbook way and the CCW (California Cycle Works) way. The correct clearance on the closing shim is between 0.03mm and 0.05mm, (0.0015” in real money) basically sod all and shims that thick are a) extremely difficult to manipulate and b) virtually impossible to be accurate with when trying to insert them between the sides of a rotating shim collar and a forged fork with access to only one side which is subject to a moderate closing spring pressure. I tried the Ducati manual method and got inconsistent results. The CCW way involves setting the opening shim and then measuring the opening shim gap with the closing shim fork pressed down with a screwdriver and subtracting the total clearance from the clearance with the closing rocker under closing spring pressure. I spent ages trying to get two results to add up - it was nevertheless more consistent than the Ducati manual method. After 3 hours I had the opening clearance about 0.005 too tight and the closing clearance about 0,01 too loose. Much of this time was spent figure of eighting the shims on 600 grade wet and dry to reduce their thickness. Part of the reason it took me three hours was I spent about an hour (on 3 separate occasions ) looking for my fancy USA collets which had ejected themselves past my face as they failed to engage properly as I released the tension on the closing shim. All good fun- and I am sure I will get better at it with more practice. PS I tested the exhaust valve by pouring methylated spirit down the exhaust port and it seals perfectly. – Result.