I have a 1973 Tiger 750 chopper with a 5 speed. Running a 20 tooth sprocket now and would like to know if changing to a 21 tooth makes a noticible difference in rpms at crusing speeds (60-65mph) Thanx for your time 73Tiger
73, first of all, the 21 tooth will not fit through the opening without making it bigger. It would be easier and only cost similat to fit a 3 tooth less rear sprocket. One on the front = 3 off the rear. Yes it will make 60/65 mph cruising less rpm.
Roy.
Thanks. Am new to the internet and sometimes hard to get info on this bike ,do appreciate the response. Will now try searching USA for a three tooth smaller rear. Any suggestions ?
MAP Cycle 727-381-1151. You can talk to a person and order the correct part. Get a parts book for your motor, so you can order by part number. Since you have a chopper, check to make sure the sprocket IS Triumph!
Called MAPS and they do not show any rear sprocket for this 73 model other than the 47 tooth. (It is a 1973 Triumph conical rear) All other sites, British Only etc., have given the same result although I see talk of a 43 tooth rear gear on the web. I have both the parts and repair manual but they do not show a smaller rear sprocket option but I belive its out there. Anyone know of an early 70s 5 bolt rear sprocket smaller than 47 tooth? Thanks for your help. 73 Tiger
There is very little difference in the diameter of the 16" tire and the 18" tire. Certainly not enough to make much of a noticable difference in final gearing.
If you are competant mechanically, you can always pull the transmission gearset out and slip in the 21 tooth sprocket that way if you don't want to notch the 'window' to fit it through that way.
I once calculated that the difference swapping the sprocket from 20 to 21 teeth is some 150 rpm`s. Not worth the sweat.
The 47 tooth rearsprocket is the smallest you can get that the conical hub allows.
To fit smaller rear-sprockets you need a different hub eg using the hub with the disc-brake. There you can bolt-on a 43tooth sprocket.
So with a 20-47 combo you cruise with a 65mph at 4000rpm.
With a 20-43 combo (discbrake) it`s a 75mph at 4000rpm ( I believe to remember)
Ray, Thanks that is just the kind of info I was looking for. After looking closely at the rear wheel it is obvious a smaller gear would never bolt up as the chain rides right at the sprocket mounting bolt heads as it is. The bike runs perfectly but winds up very quickly and at 50 or 55 ive shifted to 5th and feel like there should be one more gear. Is this the norm? Dont have a tach or tach drive. Also been told that even though this is definitly a 73 Tiger 750 it originally had a 4 speed? Thanks ever so much for your time 73 Tiger
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