RGS rear brake hub/sprocket?

[chaterlea25]

Hi All,
As some of you will know I have an ongoing project on an RGS, I have been gathering bits as I come across them,
The rear brake drum/sprocket that is currently fitted is 46 tooth which I am led to believe is from a single cylinder model???
I know Goldies had a finned hub with 46 teeth?? and that twins have 42 tooth sprockets
 
The question really is, should an RGS 42 teeth hub have cooling fins ??

Awaiting all the wisdom

  John O R

[trevinoz]

Hi John,
                 An RGS should have a 46 tooth rear drum with cooling fins.
Trev.

[chaterlea25]

Hi Trev,
I'm supposing this is why the RGS was fitted with a 23 or 24 tooth engine sprocket???

23 x 43 and 19 x 46 = 4.53
24 x 43 and 19 x 46 = 4.34

where as the SR ??

21 x 43 and  19 x 42 = 4.53
22 x 43 and  19 x 42 = 4.32

that said my SR is running 23 x43 and 19 x 42 = 4.13 without a bother ???

The "moneypit" SR on the bench has a 49 tooth rear wheel sprocket, presuming sidecar???

Regards
John O R

[trevinoz]

Hi John,
               As far as I know, the RGS only had 23 or 22 tooth engine sprockets fitted. The 22 presumably to allow the bike to get away easier with the RRT2 box.
I suppose your SR has the cast iron full width hub. I have not seen any other sprocket for this type than the standard 42 tooth.
The sidecar gearing was usually done on the primary drive on the swinging arm models and the final drive on the rigid/plunger models.
Trev.