XS650 Clutch Worm Mod (rebent arm) testing

[DogBunny]

Its too bad you two had no improvements.
But, for what its worth, now you know.

This was TooMany's baby, and he was very honest, pragmatic and stoic about the test results. I still like the mod. The theory is sound, and it just looks like it should work.

I'm not positive, but I think the between-the-carbs clutch cable routing was used on models with un-linked carbs, so that would be 1970-1975.

I don't even run my clutch cable under the tank. It is totally in free air. The only thing keeping it from flopping around is that I thread it under the spark plug wire. Been this way for years and years. I have a very easy clutch pull.
BTW, I finally ditched this color scheme...

 

[angus67]

BTW, I finally ditched this color scheme...
Sure you did...huh-huh The DIE saves it. I would have kept it, but I'm kooky like that.
Mines easy too. its just a 1980 two piece rod. I have mikes XS clutch worm. works fine. the arm has the extra hole, but that's been covered. I went with more leverage.(the hole closer to pivot.) I have a touch of arthritis, but action is still nice.

 

[TwoManyXS1Bs]

BTW, I finally ditched this color scheme...

I remember when I met-up with DogBunny and saw his paint scheme, my first thoughts were "Man, this guy must've eaten a lotta ladybugs. Probably smiles a lot while riding. Ladybugs beware!".

DogBunny's clutch action is very light and smooth. On the Displacement-travel/Pull-force ranking scale, his is still on top. It would be very difficult to approach that with factory clutch routing...

 

[vsop-dk]

Thanks for clearifying on this.

The casecutter tool was tested by me, and is a great tool, but the mod itself did not apply in my case because I run my clutch cable to the left of my carbs. This mod is for people who run the cable between their carbs.

TwoManyXS1Bs tested clutch pulls before and after doing the worm gear bending mod (which is a different mod) using a digital spring gauge, and determined that it does not make a significant difference.

 

[gggGary]

Tungsten disulfide, cable, worm, hmm.

2M can you point me to the specs for the pull measure set up. would like to check a few of my bikes, would even be willing to buy a new cable and devise the best way to pre-treat with the TDS, My gut feeling that it is BEST applied before any other lube is applied for best adhesion and filling of pore structure. Maybe we should have a loaner pull tester and database.... FWIW the TDS seems to have a great affinity for plastic and rubber. I used it on the fork seals I installed on madness and have had zero oil escape even with rather high fill levels in that fork.

 

[TwoManyXS1Bs]

Gary, all the pull tests were done using a Walmart Berkeley digital fish scale, 0-50lbs. Link the hook at the outer end of the lever, at the base of the ball. Then, do a slow, consistent pull, straight back, at about 1 Inch-per-Second. It's important that all readings be taken while the lever is in motion.

A pic of DogBunny doing a pull.


Notice that you have to brace the handlebar with your other hand.

At the halfway point thru this 3-second pull, take a reading. Do several pulls, toss the goof-ups, average the rest.

Just for fun, I just took a reading on mine and got 12 pounds.

You may want to take clutch worm plunge depth readings, too. That way you can get scoring values, mills-per-pound. I can make you a dialgauge adapter, as shown here (posts 90-92):

Clutch worm depth dialgauge-post90

But, I'd need an old snap-on adjuster cover for this.

Or you can do the angle gauge, and derive the plunge depths at 3.5 mills per degree.

Clutch worm rotation gauge

 

[gggGary]

Johnny on the spot bought a digital fish scale, checked accuracy against my postal scale, within .01 pound on a 20 lb item.
went around and tested several bikes;
an old 73 that been sitting for decades about 20 lbs and rough, added some oil/WS2 at the perch, dropped to about 16-17 pounds
Period piece about 13-14 pounds This needs the perch pivot R&R done.
Resto 13-14
Madness (6 barnett springs) 18 pounds.
all but 73 have "best practices" cable routing and "good" clutch action.

 

[TwoManyXS1Bs]

Those values all sound quite reasonable.
When I first started this adventure, my clutch pull was about 25 lbs.
Once it got below 18 lbs, I was actually satisfied with the feel.
Now, at 12 lbs, quite satisfied.

And should probably stop there.

Now, this WS2 stuff, and some other ideas, plus some OCD, may jump back in...