24 tooth counter shaft sprocket

I have recently obtained a 24 tooth counter shaft sprocket and wanted to get some feedback from the forum before installing this sprocket. Is anyone running or has run this size sprocket? My 0-100mph days are over, I am more interested in cruising across country.

I am concerned about accelerating onto the interstate acceleration ramps and still having enough roll on from 50mph +. I would like to have a little higher cruising speed, 70+ and still keep the RPM's down. I am presently running stock sprockets front and rear, 20 tooth on the counter shaft of my 75' 850 MK3. The engine is stock.

Hi,
I once ran a 23 on my 74 850, I found it to be a little too much for the type of riding I do. Even on the highway I'd wager the 24 tooth will be somewhat tall. Another thing to consider is whether or not you are pushing a windshield, and if so, what type, streamlined or parachutte ?

GB

I've been running a 24-tooth sprocket with a Combat 750 for about twenty years now. I'll probably never go back to something smaller. Zero-to-60 times remain comparable because you don't change out of first gear. Gas mieage improves, highway revs go way down--and if you need it there's always third gear. Having an optional overdrive is useful almost every day--with my tall 18-inch tire 4000 rpm is a leisurely 89 mph on the tollway. My rebuilds seem to last a lot longer as well.


Tim Kraakevik
kraakevik@voyager.net
Three Commandos

Swampy,
Here's a link to the NOC tech file on ratios. It'll give you an idea what you'll be getting by going to oversize gearbox sprockets.
http://www.nortonownersclub.org/support ... box-ratios
They don't go into the fact that increasing the sprocket size puts higher loads on the gearbox. It's difficult to make a convincing case for this, but it does. If you've been considering getting a belt primary, one of the possible benefits is a variety of ratios available. You can overdive the primary compared to stock without making life more difficult for the gearbox.
I'm running a Hayward belt that ups the ratio to 2:1 and a 21 tooth rear sprocket. My speedo and tach are not very trustworthy but 4000rpm is good for around 80+mph. Whatever RPM and MPH it actually comes out to be, my motor's sweetspot is making me go faster than almost everybody else.

I have a 22 on mine and I think that's too tall! But I admit to being more of a stop-light GP guy than a long distance cruiser. I am thinking of going to a 520 0-ring chain and dropping to a 21 or maybe even a 20. But, as you noted, it's all about the type of riding you do. I wish it was easier to swap the ratio than it is; it would be nice to be able to change it to fit the application...

You will lose the ability to putz along at 40-45 mph in top gear and still have respectable throttle response. But if highway cruising is your thing, I suppose it's OK. 2nd gear will be a lot of fun.

I think a practical issue is with the clutch. Before and after the highway, you will encounter some stop and go driving. The clutch gets a little overused in this instance. When you put in your 24 thoother, you may want to slap in some fresh clutch disks or at least make sure everthing is up to snuff in that area.
Charging from the stator can also be an issue due to low RPM's. I would make sure you are good there also.

FWIW Although i have a 21 tooth sprocket, the RGM belt drive I installed late this winter lowered my ratio to the point of 3750rpm = 70mph.

If I remember correctly, the chainguard/lip on the inner primary cover must be removed to make room for a 14 tooth sprocket. I have a 22 tooth on my 850 Interstate, a 21 tooth on my big-valve 850 cafe bike. The hot-rod motor handles the 21 easily, but there is a noticeable drop in acceleration in the Interstate over both the cafe bike and my stock (19-tooth) 750 Roadster. On the freeway, the 22 tooth is the perfect sprocket for me.