sprockets

Hi Pete,

   Unfortunately not! ES2 main-shaft is 1" diameter, Inter is 1+1/8" and Dommie 1+5/32". Was there a reason you wanted to fit a Dommie sprocket?

Hi again,

   I think the Model 19 was fitted with a 21T engine sprocket for solo use so should be some around either new or s/hand. If not you might be able to fit a 20T gearbox sprocket if it's a laydown type which will be about the same increase.

Hi Pete.

I put a 21 t gearbox sprocket from a commando and a 20 t engine sprocket on my model 19S. It pulls them just fine. BTW I just left the 43 t rear wheel drum and sprocket at the 1/4" tooth width, didn't see any reason to change them as the 3/8" chain works just fine.

RGM Motors carries a range of ES2 type engine sprockets in the three different offsets Nortons used over the years. Measure yours before ordering to determine the offset.

I fitted a 21 tooth because that's what the shop had in stock and I was planning on fooling with the gearing anyway!

Regards,

Albert

hello 

i like to put a 20t sprocket on the engine, as we all know there are 3 types. nr1 teeth near to carter,nr 2 middle and nr 3 teeth far from carter.  what sprocket type is the right one for a big4. 1952???

what is the influence on speed and power wenn changing the gearbox sprocket from 19t into 20t?

If you're buying a new gearbox sprocket you'll probably need the extra spacer that RGM stock to line up the rear chain.  The new sprockets are slightly different and do not have a "shoulder" to fit against the main gearbox bearing.

Philip.

I got a gearbox sprocket for my 1952 ES2 (laydown box) from RGM last year and it fitted perfectly with no need for a spacer.

Hello Rob,

   It will be easy to fit a 20T engine sprocket from an ES2 of the same year, although you will need a half link in the chain to get the correct adjustment. The off-set you need is the one that is closest to the crankcase. Under good conditions this will put 4mph (6kph) on the top speed, but the Big 4 does not have a large power out-put so you will need to use the gearbox more on hills and in traffic. One benefit might be a more comfortable cruising speed.

Thanks richard,  i flattened to cilinder head and put a 1 1/16  carb on it. So this 20t engine and 20t gearbox will be not so bad at all. Hope to meet j

You in holland/ kampen

Regards rob

Hi Rob,

   I don't think I will get to Kampen as June is a busy time for me, but if I can help at all you can contact me on my email through this forum. Good luck with your side-valve tuning!

Richard.

Hi Pete,

   The Model 19 bottom gear ratio is 2.97 to 1 internal ratio (13T x 29T) but you could fit an AMC bottom gear set (14T x 28T) which would lift the ratio to 2.66 to 1. Not a big difference but it might help. The only thing you will need to do is grind off the extended boss on the small 14T gear to make it the same as the 13T one.