Yet Another Clutch Mod. Thread

Jim

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I've been gettin' the SG ready for ridin' the last couple of days, so I had the LH sidecover off checking everything over. I also had the clutch cable out to lube and possibly find a better routing... so doing a little moddin' just seemed like natural mission creep. :rolleyes:
Clutch pull wasn't bad to begin with... about 12-14 lbs to full release, but I'd like better. Having worked as a mechanic for the better part of 50 yrs, the arthritis in my hands was bad enough some days last year that I passed on some good riding days. If I can make a substantial drop in clutch force... well, ridin' on those days will be more enjoyable.
First thing I did was re-read @TwoManyXS1Bs excellent article on the worm actuator mods. That gave me a good north bearing to start. I'm using the XS400 1L9 actuator with a lever length of 35mm. Other than that (and a Motion Pro cable) the clutch is box stock 1980 vintage... 2 piece pushrod and all.
I decided to start with extending it to 50mm but... I didn't want to weld or modify the 1L9 arm in any way that I couldn't return back to original, so I could try sumpin' else.
So here's how I did it. Made an outline of the existing arm on a piece of cardboard and added a hole at 50mm. The math says this is a 30% increase in length.

template.jpg



Drew an outline to pick up the new 50mm hole and cut it out.


tplate cutout.jpg



Transferred that to a piece of scrap metal the correct thickness.....


xfer to metal.jpg


... and drilled the holes and cut it out.


cut metal.jpg


Painted it for corrosion protection and put it together.


painted and assembled.jpg


done2.jpg

final.jpg


The screw is a 1/4" NAS countersunk. I did have to make one mod to the original arm. I ruined the cotter pin used to hold the clevis pin in place so I drilled it out to fit the cotters I had on hand. Other than that, it can easily be returned to stock form. :rolleyes:
All back together and I'm amazed at the difference. I'm still playing around with the cable routing... but right now the worm starts pushing on the clutch at around 4-4.5 lbs and is fully disengaged at somewhere around 8-9 lbs.
I've still got a handful of spring wake-up items to finish, but I should have some hard numbers and riding impressions up here by the end of the week.
 
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Edit: Jim, what was the benefit of using the XS400 worm in the first place?
The 1L9 arm bends down toward the worm whereas the 650 arm bends away from the worm... increasing the side loading.
Did you modify the worm actuator like the mod thread outlines?
No, as much as I like breaking out the ol' TIGer...I didn't want to permanently weld a mod on it. Also, I think mine's about 5mm more arm than was ever tested in that thread.
 
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It sure sounds like a great mod Jim - well done!

The only potential issue I can see is if the rotation of the actuator (worm) isn’t sufficient to fully disengage the clutch. As long as that is OK - then all good!
 
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if the rotation of the actuator (worm) isn’t sufficient to disengage the clutch.
Which was why I didn't want to weld it...easy to remake it a little shorter. I had a lot more lever than I needed before, so fingers crossed... I'm good.
 
Nice clean looking mod!

I reached the same conclusions with my experiments with the clutch worm. After trying different arm lengths and clutch cables and measuring the results, the best results came with a long arm clutch actuator and a Motion Pro cable.
 
Very nice fabrication, and I think you will be glad that you made it reversible. Because -- and I apologize for being a contrarian -- but I am skeptical.

I'm pretty sure that the longest actuator lever arm length that Yamaha ever used on an XS650 was 45mm. I believe that anything longer than that will prove problematic on a running engine, and even more so when that engine is very hot. I hope that you prove me wrong.

On my 1976, I am using one of those long 45mm lever arms, but I have drilled a choked-up hole into it that shortens it to about 36mm. This is pretty much standard procedure for me when I run across one of those long arms.

On a more upbeat note: I believe you are running buckhorns -- they lend themselves to an extremely relaxed clutch cable routing. I run buckhorns. It is possible to run the cable completely exposed, just hanging out in mid-air, to the of the triples and forks, to the left of the tank, to the left of the carbs, to the left of the whole rest of the bike. Not threaded in, or tucked behind anything. Just a great big sweeping air swoop. Try it. This will give you as easy a clutch pull as possible, but of course, is impractical. Start with that, and then you will need to pin it down somewhere. Mine just barely tucks under the left side of the tank, anchored by a loose zip tie.
 
Just a great big sweeping air swoop. Try it. This will give you as easy a clutch pull as possible, but of course, is impractical. Start with that, and then you will need to pin it down somewhere. Mine just barely tucks under the left side of the tank, anchored by a loose zip tie.
That's exactly how it was before... and how it currently is. And prolly how it will end up. :rolleyes:
 
I had my worm apart (oooh, that sounds kinda weird) a couple of weeks ago and I carefully cleaned and lubed the inside of the power screw and I am quite surprised at the difference it made.

It had been lubed before, but not for a little while and just cleaning and re-greasing it was surprisingly effective at making the clutch smoother and reducing the pull.
 
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Nicly done Jim..........Link below will answer most questions.........cross reference information into as many like minded threads

Post #65 .............Here is 5 Twins thread on the differences in Actuators and how to mod the XS400 actuator to clock it to an XS650 clutch
http://www.xs650.com/threads/200-special.51454/page-4#post-606933
 
cross reference information into as many like minded threads
Thanks Doug.
Yeah, I plan on linking.... after I test it out. ;) Like Dogbunny said above, there's a distinct possibility it's too long. I knew from Twomany's work (and contributors to that effort) that jumping from 45 to 50mm was a big jump. I'm out beyond the edge on this one. We'll see.
 
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Uh oh! You know what lies out there!
View attachment 165433 I’m very happy with my two set at 45mm. You might have a little trouble finding neutral?
Yeah.. they're out there. ;)
Here's the one kinda sorta test I did....
This morning before I took it apart, I pulled the clutch in and pushed the start lever down by hand numerous times... Made a mental note of force needed. Did the same after.... and couldn't feel any discernible difference. Unscientific I know... but a good sign.
 
The 1L9 arm bends down toward the worm whereas the 650 arm bends away from the worm... increasing the side loading.

No, as much as I like breaking out the ol' TIGer...I didn't want to permanently weld a mod on it. Also, I think mine's about 5MM more arm than was ever tested in that thread.

I meant did you shorten the xs400 parts down to reclock them?
 
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