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

 

/bump

I still haven't been able to find a definite answer regarding these two issues. Can anyone lend a hand?

thanks,

Chris

 

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

 

61-86 transmisson drive speedo are 1:1 ratio

 

My book says '54 - '72 K & XL transmission drive ratio is 2:1.

 

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