1971 XLCH Speedometer Ratio?
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1971 XLCH Speedometer Ratio?
From what I can tell in my research, a 1:1 ratio speedometer is needed for a transmission drive speedometer for a 71 xlch. Is this correct or is it a 2:1?
Also, does anyone happen to know if the lower (transmission side) of the cable is a 7/8" x 18 nut?
Thanks,
Chris
Also, does anyone happen to know if the lower (transmission side) of the cable is a 7/8" x 18 nut?
Thanks,
Chris
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Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: 1971 XLCH Speedometer Ratio?
Chris.....
I have looked everywhere I can think of and have not found an answer. No mention of the ratio is in the factory manual.
The only thing I can suggest is this:
1)Put the bike on a stand with the rear wheel off the ground.
2)Pull out both spark plugs (so the engine will spin easily)
{Step 2 is not needed if the speedo drive rotates in neutral. Of this I am not sure, so jump to step 3 and try it in neutral}
3)Disconnect the speedo cable at the head and bring the cable around so that you can easily see it from the rear wheel location.
4)Put the bike in 4th gear {again, not needed if drive rotates in neutral} and place a chalk mark on the rear tire sidewall.
5)Rotate the wheel exactly 1 revolution, while watching the inner speedo cable turn and carefully note how many times it turns with one rotation of the rear wheel.
If the inner cable turns 2 times while the wheel turns only 1 time.....Your answer is the ratio is 2:1 for the needed head. I know of no other way to easily determine the ratio. Maybe another member has a better solution? I'd love to hear it.........pg
I have looked everywhere I can think of and have not found an answer. No mention of the ratio is in the factory manual.
The only thing I can suggest is this:
1)Put the bike on a stand with the rear wheel off the ground.
2)Pull out both spark plugs (so the engine will spin easily)
{Step 2 is not needed if the speedo drive rotates in neutral. Of this I am not sure, so jump to step 3 and try it in neutral}
3)Disconnect the speedo cable at the head and bring the cable around so that you can easily see it from the rear wheel location.
4)Put the bike in 4th gear {again, not needed if drive rotates in neutral} and place a chalk mark on the rear tire sidewall.
5)Rotate the wheel exactly 1 revolution, while watching the inner speedo cable turn and carefully note how many times it turns with one rotation of the rear wheel.
If the inner cable turns 2 times while the wheel turns only 1 time.....Your answer is the ratio is 2:1 for the needed head. I know of no other way to easily determine the ratio. Maybe another member has a better solution? I'd love to hear it.........pg
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
Likes: 17
From: Houston Texas
RE: 1971 XLCH Speedometer Ratio?
I have to chime in with Poco on that one.
Chris, you noticed I gave an example of the wheel turning one time and the cable turning 2 times resulting in a 2:1 ratio. That was because I have always felt the ratio was 2:1, but have not seen it in print myself.
Regarding another post on the subject, saying the ratio was 1:1.....well. I have to seriously doubt that is correct.
A lot of the Smith brand speedometers are a 2:1 ratio and the tachometers are as well. If the industry can buy a head ready made, then it follows that the cheapest method is to install a like drive to match it.
I bet 2:1 is correct, but you can do what I suggested to verify the ratio once and for all........pg
Chris, you noticed I gave an example of the wheel turning one time and the cable turning 2 times resulting in a 2:1 ratio. That was because I have always felt the ratio was 2:1, but have not seen it in print myself.
Regarding another post on the subject, saying the ratio was 1:1.....well. I have to seriously doubt that is correct.
A lot of the Smith brand speedometers are a 2:1 ratio and the tachometers are as well. If the industry can buy a head ready made, then it follows that the cheapest method is to install a like drive to match it.
I bet 2:1 is correct, but you can do what I suggested to verify the ratio once and for all........pg
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1971, cable, harley, ironhead, ratio, ratios, repair, spedometer, speedo, speedometer, speedometers, speedomoter, sporster, sportster, xlch
