19 tooth versus 21 tooth gear box sprocket.

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htown16

htown16

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Two bikes 71 and 72 750's mostly identical one has a 19 tooth gearbox sprocket and the other has a 21. At 50 mph the 19 is turning 3500 rpm and at 50 the 21 is turning 3000 rpm. If I was doing a lot of highway riding I would switch the 19 for another 21. Not a trivial job though pulling the primary apart.
 
Depends on how fast you go on the highways. I've had a 19 since new in '72 and prefer the blastoffability. If I lived out west I would probably want a 21.
 
Is there a question here? Seems like you have enough choices of rides to pick what vehicle to take out based on the route. After living in Austin, my memory of riding in TX was that you don't need low gearing. Maybe consider a 20T if you want something to be quick and not too buzzy at 60-70 mph.
Also depends if you have belt drive as that makes gearing a little taller.
As Russ sez, a 750 with 19T is the original 70's crotch rocket setup. Nice to appreciate that G force when you want it, I will maintain it in the 750 to remind me of essence of riding in the 70's, blowing off anything else on the street. Not as loud as a Harley, but much faster than any XLCH or Superglide.
 
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When I got my current 850 in '06 it had a 23 tooth sprocket. My 750 back in the day had the 19. I couldn't deal with the lethargic 23 at all and initially figured on installing a 19. But then I figured I'd give the engine a bit of a break so installed a 20 when I converted to the CNW 520 chain mod. I like acceleration and the 20 is a decent compromise for me...even though occasionally I wish had the 19! ;)
 
Most bikes imported to America had a lower tooth number on the gearbox for stop light departure speed.
The price is mpg and wear rate on the bike. Commando will pull a high sprocket but if you live in hilly country
you may not be happy with it. Not to forget rider weight as well.
 
Mine's an 850 with a 23t. Probably, it's one or two teeth too many for regular use. It lopes everywhere, rather than charging. Marathon athlete vs. 100m sprinter. I won't change it, I like it being different. If I changed my bikes to suit me, they'd all be too much the same.
 
htown16 said:
Two bikes 71 and 72 750's mostly identical one has a 19 tooth gearbox sprocket and the other has a 21. At 50 mph the 19 is turning 3500 rpm and at 50 the 21 is turning 3000 rpm. If I was doing a lot of highway riding I would switch the 19 for another 21. Not a trivial job though pulling the primary apart.
Click to expand...
I believe I’ve seen something is writing saying 300rpms per tooth. I put a 21T on my combat in ‘98 and haven’t been tempted to go back to the 19T....l’m in the west. The ‘69 750 S I’m selling still has a 19T, but I never really intended to ride it.
 
With a belt drive you can get to the sprocket super quick. No mess to clean up. Pop the cover off, take the clutch apart, remove the alternator. Then just free the from pulley and off it comes. Three bolts that hold the inner cover on and you’re done. Make sure you have the giant Whitworth wrench for the sprocket nut (left hand thread!) and you’re done!

Yes, I just went from 22T to 20T and it’s much better.
 
Go as small a sprocket as you can get away with. Way more funnage. And that's what it's all about , right ?
 
Just a reminder folks, the reason Swoosh has gone from 22t to 20t is becasue he’s fitted a Maney belt drive that raises the gearing (around 10% IIRC)...

So this isn’t a generic ‘l lowered the gearing and changed my life’ kinda thread.
 
Back in the 70's my 750 blitzed everything it came across. . In the 2000's, when I got my 850, I got the opportunity to change it from a 20 tooth to a 21 tooth. Both bikes are as they are going to be till I cant ride any more. Got the best of both worlds.
 
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