21 or 22 tooth for 750

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Feb 20, 2008
I have read that putting a 21 tooth sprocket on 750 is ok but a 22 will be hard on the transmission. But on a 850 a 22 is ok. I maybe slow and drunk but what gives with that?
The higher the number of sprocket teeth, the more stress on the transmission gears and case. A belt drive can change the ratio at the primary which can give the desired lower overall ratio without significantly increasing the stress on the transmission.

It is generally thought that due to the increased torque of the engine, the 850 can perform better with 21 and 22 tooth sprockets but a 750 will struggle and a noticeable drop in acceleration will result.

I currently have stock 750's with 19 and 20 tooth sprockets, a warmed over 850 with a 21 and a stock 850 (Interstate) with a 22. The 19 is not suited for more than a short blast down the freeway, where the 20 is somewhat better without sacrificing much acceleration. The 21 on the 850 cafe racer is quite good. A 22 would help top speed, but with the cam, carbs, and head work would probably be a pain around town and require slipping the clutch on normal starts. The 22 on the Interstate (stock 30mm head with a 2S grind cam) is quite nice on the freeway, still does well around town, but is certainly no jackrabbit on acceleration. Launching requires just a little more clutch slip, but not objectionable. All of these bikes have the stock chain primary. After more than 10 years, the box with the 22 tooth sprocket is stil intact with no problems, but I don't chase Gixxers on it either.
Seems to me like either a 21 or 22 tooth sprocket with standard primary will be too tall for a 750 but I only have an 850 so can't comment directly. I have a 22-tooth sprocket fitted, and as Ron says, it is quite nice on the highway. Runs about 3500 rpm at 60 mph and I can easily get 55 mpg with a single 36mm Mikuni. I think this gearing is a bit tall for twisty two lane roads and I am probably going to change over to a 21-tooth the next time I have the primary apart. The bike originally had a 20-tooth on it which was too low for my taste. I figure a 21-tooth will be the best all-round sprocket for the 850.
I haven't really looked but by feel I think my current bike has a 19 tooth.
It's really fun on mountain roads as that and the instant engine response makes it feel more powerful than it is.
I think this bike would really get dismal fast on the freeway though.
I run two 750s, both with 21 tooth sprockets and they go very well indeed, with no problems getting away from traffic lights and no primary/gearbox issues. One is in standard tune the other is a modified cafe racer with S4 cam, gas flowed and skimmed head etc. Even though there is no scope for touring type riding in Hong Kong, I like the higher gearing, because it seems to put the shifting points into a more useable speed range for my type of riding.
Thanks for all the feed back, much appreciated Ive decided to go with the 21 .
1971 750
.Just over 600 miles on fresh rebuild, the more I ride it the better it runs

I have a 73 850. When I bought parts for a 520 x-ring conversion (which, BTW, I highly recommend. Nothing like NOT worrying about your chain snapping and taking your bike AND leg with it...), I ordered what I thought was the same sprocket I'd be taking off...a 20T.

Got in there and found I had a 19T installed. Replaced it with the new 20T.

Damned if I feel any difference.

Also put an 18" tire on the back, so the net difference is somewhat smaller. And for the most part I don't take the Snorter on any long extended freeway excursions.

FWIW. I like the 20. Would've kept the 19 if I'd known it was there, but no material difference. No desire to go higher, but see above re riding style.

Best regards - B
If you don't run the bike like we did as kids all you might notice is a higher RPM at cruising speed. The smaller tire may compensate as you say.
When these were everyday transport for me I think I used a 20 tooth but I had a few sprockets around.
When I bought parts for a 520 x-ring conversion (which, BTW, I highly recommend. Nothing like NOT worrying about your chain snapping and taking your bike AND leg with it...),

Sorry off topic (kind off) Is someone doing a kit for this?

BTW 22 tooth on all 4 Commando's but going to drop the 750 back to 21.
Got my 520 x-ring conversion from Colorado Norton Works. There are no doubt others - e.g., Old Britts does the work also.
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