2M or dps650rider....................do either of you have an aluminum push rod that is for sale?
Y'know, I thought maybe the wide-tire / offset-sprocket folks would catch on this mod.
You're the first I've heard to do this for that reason.
So, I dug out my collection of worm gears and it turns out, I had more than I thought. Besides three 650 variants, I have both an XS500 and XS400 "1L9" worm.
You were right 2Many, besides the step-down off-set, the 400 and 500 worms are clocked a little differently .....
The 650 arms fully retracted all clock about at the 7 o'clock position, as you've noted .....
The 400 and 500 arms are more like 7:30 or 8 .....
The arm length between these two differs as well. The XS500 arm is rather short, maybe shorter than ideal for us. It actually matches the length of the early XS1 650 arm .....
The XS400 arm is longer and matches the mid-mount location on the later 650 worm. This one may be ideal for us. Also of note is that the 400 arm appears to be stamped with it's part number 3 digit prefix (1L9). This should make I.D.ing them easy .....
So, the clocking may need adjusting a spline or two but I guess installing one is the only way to know for sure. If we get very lucky, maybe these will match your re-clocked 650 version the way they are. Wouldn't that be nice, a drop-in re-bent, re-clocked worm.
I've also given some thought to the short 500 arm. Just flattening it out would make it a little longer and maybe long enough. It would be sort of a compromise between the stepped up originals and the stepped down versions, but could offer some improvement. The only slight change in stepping may also eliminate the need to cut the cable seat on the case.
I was also thinking, your original premise here was that the high mounted cable was inducing a "tip over" effect in the worm and binding it. Couldn't dropping the cable attachment too low have the same effect, just in the opposite direction? The high mount would lift up on the worm (besides twisting it) and cock it away from the arm. A mount that was too low might pull down on the arm as it twists, cocking the worm towards the arm. Maybe an arm that sticks straight out is the best compromise?
OK, some corrections, measurements, and observations - The "371" arm is from the XS500. The "1L9" arm is from the XS400 (and XS360) up to about '81. Apparently the "12R" long arm version was used on the last couple 400 model years ('81 & '82).
The center to clevis hole distance on the "1L9" and the late mid-hole 650 arm is the same, about 1.4" (35mm).
I pulled out a spare side cover and mounted the "1L9" assembly. I think it will need some re-clocking. Fully inserted, it's not quite 3.875" (3 7/8") from the cable entrance point. The cable angle to the arm is also right at about 90°. Any and all pulling on the cable will move it past this ideal leverage point, not through it as we seek. Earlier in this thread, you noted 4.1" as the distance with an unadjusted, fully slackened cable connected. You figured about 4.3" fully retracted and with no cable attached to be about an ideal starting point. At near 3.9", the cable will be loose when connected and probably require more adjusting up at the hand lever, maybe more than is available.
So, a re-clocking of the "1L9" worm to achieve something like a 4.2" to 4.4" cable distance when it's fully retracted is probably what we're after.