Got popped today, 73 in a 55. I knew my speedo was off, it said 55. I had the cop follow me, and signal me when I got to 55, my speedo said around 43mph. I think my speedo is a 2-1. Where is my problem in the speedo, or the drive gear in the tranny?
Wonder how fast I was going on the hi-way, when my speedo said 70? LOL
Thanks Jim
Busted-have a question about speedo ratios
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longhorn
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64 panhead
65 panhead
70 shovel - Location: SE Minnesota
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51Hog
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Re: Busted-have a question about speedo ratios
Need more info---
What year bike?
Probably running a 25 tooth sprocket on the tranny?
A 23 tooth will get the speedo closer.
Stock back sprocket?
What year bike?
Probably running a 25 tooth sprocket on the tranny?
A 23 tooth will get the speedo closer.
Stock back sprocket?
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longhorn
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64 panhead
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70 shovel - Location: SE Minnesota
Re: Busted-have a question about speedo ratios
I don't understand why changing the countershaft sprocket would change the speedo readout? I can see where it would change the speed, but not the readout.
Here goes anyway.
The bike is licensed as a 64, because of the cases, but the parts range from 51-02. It's a mutt. Couldn't tell you what year the tranny is.
The countershaft sprocket is a 24 tooth. I didn't count the rear wheel sprocket, the old lady was having a hard enough time with the tranny sprocket. LOL
I'm thinking that the 2-1 is the correct ratio for a 64.
Even if it wasn't, couldn't a guy just change the speedometer drive gear, to correspond with the 2-1 ratio speedo? Or, would there be clearance/assembly problems?
Thanks Jim
Here goes anyway.
The bike is licensed as a 64, because of the cases, but the parts range from 51-02. It's a mutt. Couldn't tell you what year the tranny is.
The countershaft sprocket is a 24 tooth. I didn't count the rear wheel sprocket, the old lady was having a hard enough time with the tranny sprocket. LOL
I'm thinking that the 2-1 is the correct ratio for a 64.
Even if it wasn't, couldn't a guy just change the speedometer drive gear, to correspond with the 2-1 ratio speedo? Or, would there be clearance/assembly problems?
Thanks Jim
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51Hog
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Re: Busted-have a question about speedo ratios
This post will explain the sprockets.
Check out Jacks calculator a few posts from the top.
viewtopic.php?f=5&t=5134&hilit=calculator
The output sprocket on the tranny, and the rear wheel sprocket, are after the tranny gear. Any change in them will change the revolutions of the rear wheel at a given rpm which will affect the speedo. It will also affect the power available at the rear wheel. A 22 tooth on the output will get you close to being correct on the speedo. It will also raise the rpm on your engine for a given rear wheel speed. (It will pull stronger)
I do not know if you can put a different speedo gear into your tranny.
HTH--Dale
Check out Jacks calculator a few posts from the top.
viewtopic.php?f=5&t=5134&hilit=calculator
The output sprocket on the tranny, and the rear wheel sprocket, are after the tranny gear. Any change in them will change the revolutions of the rear wheel at a given rpm which will affect the speedo. It will also affect the power available at the rear wheel. A 22 tooth on the output will get you close to being correct on the speedo. It will also raise the rpm on your engine for a given rear wheel speed. (It will pull stronger)
I do not know if you can put a different speedo gear into your tranny.
HTH--Dale
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RUBONE
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Re: Busted-have a question about speedo ratios
The info on sprocket changes is correct. They are calibrated for a 22 trans and 51 rear. Any variation on those ratios will affect the readout. You CANNOT change the drive gear without changing the mating gear WITHIN the gearbox, a major task, as the tooth count is different and the gears will chew each other apart. The only way around the sprocket issue is a front or rear wheel drive unit that reads only wheel revolutions. Or have someone pace you with a known correct speedometer and make note of actual speed and remember it or mark the glass on yours!
Robbie
Robbie