G9 primary drive.

[Dan Kristiansen]

I am rebuilding a G9 from boxes of bits.
The primary drive was missing. I have purchased a sprocket (smooth bore with shock absorber 015204) along with the spacer(016584) and spring(016633).

It appears that the crankshaft isnt long enough to accept the assembly, The spacer with splines only just engages on the crankshaft.

Im told the engine is a 1955, and has tin chain cases.
Does this year have a standard sprocket without the cush drive?

Thanks.

[dave16mct]

The '55 G9 should have a sprocket with cush drive, spring etc. If the shaft is too short it's probably from a '57 on. This used an AMC clutch with the shock absorber in it. You may have to use the primary drive from a '57 on, ie sprocket and AMC clutch. Do you have a Burman B52 gearbox? The AMC clutch can be used with the Burman box but you may have to do some mods, possibly a spacer behind the clutch and longer push rod. I've done this successfully, didn't need a spacer but had to make a special adjuster on the clutch.
Dave.

[Groily]

http://archives.jampot.dk/book/Spares_l ... _twins.pdf
Should have the shock absorber. The 7th 'page' of this (no page numbers on this file) shows the parts and also the crankcase relief valve that I think you should have. The crank to take those bits is Part # 018579.
Suspect you have a later crank designed to run with an AMC cush-drive clutch if the (correct) bits you've bought won't go on. The later crank is Part #023254-023256 according to, for example, the 1957 parts lists.

What clutch and gearbox are in the pile of parts you have to hand? Originally the machine should have had a Burman B52 plus matching clutch. I don't know if a cush drive AMC clutch can be readily grafted onto the Burman mainshaft, nor do I know how easy it would be to use an AMC 'box and do it that way, nor indeed whether that would create all sorts of primary chaincase issues, engine/gearbox plate trouble, etc . . .

But - there be people here who are all-knowing and will advise I'm sure, as most combinations will have been made to work OK by someone! (Dave who beat me on the keyboard being one!)

[Dan Kristiansen]

Hi Dave,
Thanks for your reply.
It seems I have an AMC clutch with cush drive, with a Burman gearbox.
I will order the correct sprocket and go from there.
Machining up the modified parts (if required) wont be a problem.
Thanks again, Dan

[SPRIDDLER]

But - there be people here who are all-knowing and will advise I'm sure, as most combinations will have been made to work OK by someone! (Dave who beat me on the keyboard being one!)

I'm not all-knowing but I do have a good memory of the Technical Articles in the Archives.

Clutch AMC to Burman box.JPG

[dave16mct]

Hi Dan,
you will probably need a 21 tooth engine sprocket as the AMC clutch is 42 tooth.( '55 gearing is 20 engine and 40 burman clutch.)
Dave.

[Dan Kristiansen]

Thanks for all of the information.