Well, times flies and only today I decided to work a bit on the Douglas.
I had a ride in the winter and the gears still cracks.
I removed the flywheel and measured the flatness on the clutch using the set up in the enclosed picture (sorry can not make it straight). Well I have only .010"/0,25mm of variation on the disc all around. Not too bad I guess.
I also noticed that I have a black layer looking like burnt grease on the disc. This was present the first time I opened the flywheel and I do not think they are any part of the problem.
ALso the inside of the cone is rather rough. Also not a trouble as I guess as long as the flywheel and clutch disc both truns together, the whole assembly might as well run out of round, it would not affect the clutch.
When I get the bike from Andy Tiernan back in Oct 2016, the gears did not cracked. Report from Andy also says gears goes well and do not crack.
Only after I opened the clutch, cracking appeared. So I am pretty sure I made something wrong when putting everything back together. But assembly is so simple, I can see nothing that might be wrong...
The only adjustment I have are the cable on the primary chain housing. Tightening the cable, preload the cam up to a point the clutch can slip under the kick's action.
And the springs tension plate using the nut on the cam shaft. I tried using 2 springs out of 6, then 3 then very little load.
When I had the bike it had 6 springs and, again, did not cracked.
Maybe I should use 6 springs and load the springs more?
Also I have a very light play on the cam shaft. When taking it with 2 fingers, I can feel (but can't see) a slight play. Not a concern, I guess.
[Attachments converted to linked images. 07Dec21 -Doug, Admin]