higher gearing for m31.

[greasemonkey]

hi all, been enjoying riding the m31 after restoring her,one thing about it i would like change about it is the gearing.its too busy and buzzy at moderate speeds of 50-60mph.on my 1970 bonneville i have upped the gearbox sprocket from 19 teeth to 21teeth.this has made for much more relaxed cruising.has anyone done the same on a m31/g12?.would much appreciate any input on this,cheers greasemonkey

[Duncan]

How may teeth are on your other sprockets, for 1961 650 the standard gearbox sprocket was 16 teeth and the CSR was 17 teeth, it sounds like you are already running taller gearing?

[Groily]

Maybe start with checking out the crank sprocket. Some sizes are hard to find and a lot of machines seem to be on a 21, which is commonly available, but a bit small on the 650 with a 16 or 17 further back.
I've settled for 21, with a 19 on the 'box on my Mod 31 and it suits me quite well.

[greasemonkey]

hi, thanks all for your replies,i cant remember the figure but it checked out as standard on the gearbox sprocket.

[Groily]

In a long-ago post ajscomboman, as what knows a thing or three or four, said that he'd found 23 (crank - that's std btw)) and 15 ('box) was good.
I said in another long-ago post that I was happy in flat countryside (like wot I have round me) with much higher - 24 crank and whatever on the 'box - but I wasn't happy in the end as serious hills in Spain and contrary head-wind winter weather messed things up badly.
Far better at 21 / 19 or 24 / 16 and if you've got a 23 on there, a 16 (std) or 17 (CSR) on the box should be long enough I think.

[ajscomboman]

In a long-ago post ajscomboman, as what knows a thing or three or four, said that he'd found 23 (crank - that's std btw)) and 15 ('box) was good.
I said in another long-ago post that I was happy in flat countryside (like wot I have round me) with much higher - 24 crank and whatever on the 'box - but I wasn't happy in the end as serious hills in Spain and contrary head-wind winter weather messed things up badly.
Far better at 21 / 19 or 24 / 16 and if you've got a 23 on there, a 16 (std) or 17 (CSR) on the box should be long enough I think.

Good memory Bill. The 23/15 combination was ideal for the sidecar setup. For solo 650,s you can go 23/17 or 23/18 if you accept you'll have to cog down on steeper inclines. For my CSR with 10.25 pistons I'm running 24/17 and that too needs cogging down on inclines but happily potters at 65-70 along the straight.

[greasemonkey]

hi all, thanks for the replies,i have taken the plunge and ordered a 19 tooth gearbox sprocket and hoping it will suit my needs.will report back when fitted.

[greasemonkey]

hi all,an update on this thread,ordered the 19 tooth gearbox sprocket from AMC as the club did not have one in stock. when doing the job i checked the engine sprocket, that had 23 teeth which i think is standard for the bike.the original gearbox sprocket had 16 teeth also i believe standard .very pleased with the result.1st is a bit high but not a problem,third is about the same as what 4th used to be.4th is now much more relaxed but the bike still accelerates well and at 60MPH is smooth and stress free,just the job for cruising about the countryside.cheers GM.