1958 G80CS Valve timing

[clive]

Richard, was the bike running when you got it? If it was did you change the piston during your rebuild? If so was distance from the gudgeon pin to the top of the piston Dome the same? Did it have the same valve cut aways? If it was not running when you got it can the previous owner confirm if it ever ran with the reprofiled cams?
Your answers to these questions may help identify the problems. Personally I think it's likely that the timing marks scribed on may have been used in a different way however have you tried to use the method outlined in th right hand side of the black boxed area in page 1 of Kens article. If the marks are of any use this will get you going.

If that does not work there is an article in the technical section which gives all the valve timings and tells you how to test for them. It's on the club website under articles, technical tips, singles, hw single cam information. It includes cam timing for the comp models and I think covers your year.

[Transatlantic]

Thank you all for your helpful information, today I actually solved the problem!!

There are two problems here:

The timing marks on the cam wheels are completely wrong on my bike !
The supplementary information for the G80CS regarding timing, that is published has two typos relating to the exhaust valve opening and closing. I intend to write this up in more detail later, but for sure it's wrong.

First I took off the rocker cover and removed the exhaust to make sure the valves were not stuck, I compressed each spring and movement was fine. Then without the rocker cover on with the push rods sticking up , I watched the movement of the tops of the rods to determine the valve opening times.

I attached a degree wheel to the center pinion and found TDC
Rotated engine back to get to the opening of the inlet at 59 degrees BTDC
Inserted the inlet cam wheel so that the ramp of the lobe was just opening the valve.
I repeated this with the exhaust cam wheel and with each one adjusted by a few teeth either way checking against the published degree setting until it was correct.
It became obvious the although the degree settings for the exhaust were correct in the supplement, the reference to BBDC and ATDC could not be correct.
Then I resembled the top end and adjusted the tappets to the correct tolerance.
The valve operation now looks logical and the engine turns over without the binding that was previously occurring.
Took about 5 hours but I feel very satisfied with the results.
Thanks for all the suggestions and it was very useful to check to eliminate other causes.
Finally I took my dremel tool and marked new indexes on the wheels

[Transatlantic]

Richard, was the bike running when you got it? If it was did you change the piston during your rebuild? If so was distance from the gudgeon pin to the top of the piston Dome the same? Did it have the same valve cut aways? If it was not running when you got it can the previous owner confirm if it ever ran with the reprofiled cams?
Your answers to these questions may help identify the problems. Personally I think it's likely that the timing marks scribed on may have been used in a different way however have you tried to use the method outlined in th right hand side of the black boxed area in page 1 of Kens article. If the marks are of any use this will get you going.

If that does not work there is an article in the technical section which gives all the valve timings and tells you how to test for them. It's on the club website under articles, technical tips, singles, hw single cam information. It includes cam timing for the comp models and I think covers your year.

Thanks Clive - I think you're right the marks are not intended for the normal use