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Topic-icon clutch engages very early

  • Wursthead
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1 month 2 weeks ago #5624 by Wursthead
clutch engages very early was created by Wursthead
I have a 78RS100R I finally got going thanks to the help of you guys out there!
one question..the clutch engages right away upon release. Is that an adjustment or maybe a deeper issue?

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1 month 2 weeks ago - 1 month 2 weeks ago #5625 by 8053
Replied by 8053 on topic clutch engages very early
If it were a bike that was new to me, I would play with the adjustment of the clutch arm on the back of the transmission, and/or the cable at the handlebar end. If the clutch starts to engage with very little release motion at the hand lever, it would follow that there would be considerable free-play at the lever when fully released.

James Strickland, IL. Airmarshal
Last edit: 1 month 2 weeks ago by 8053.

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1 month 2 weeks ago #5626 by Wursthead
Replied by Wursthead on topic clutch engages very early
thanks James. Just to be clear because im not the best mechanic around or at all but pretty handy with taking direction..are you saying start with the arm on the back of tranny and the lever at the same time to get it right? is there a process in order to get it right?
I appreciate your time

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1 month 2 weeks ago - 1 month 2 weeks ago #5627 by 8053
Replied by 8053 on topic clutch engages very early
To make a judgement about the clutch free-play, You start at the handle bar end. How far can you pull the clutch lever before you feel the tension increase when the clutch is about to be dis-engaged? If the lever gets half way to the hand grip before the tension takes up, there is too much slack in the assembly. Now then, on the lower right side of the transmission you can see where the clutch cable engages the little swing arm on the throw out mechanism. There should be a coil type spring pushing the arm away from the back cover of the transmission. Another way to assess the free-play would be to take your finger and press on the bare cable until you can feel the clutch pushrod start to push against the spring diaphragm inside the clutch assembly. The distance from the cable boss to the cable rest of the throw out arm is supposed to be 201mm. You can cut a coat hanger wire to make a 201mm gauge. Try to adjust the the handle bar end adjuster until the 201mm distance is established. The final adjustment of free-play is achieved with the lock nut adjuster higher up on the clutch release arm close to where the clutch arm pivot pin is fitted. You may not have to make an adjustment there after the 201mm is established. ( The 201 span is considered to be ideal to achieve the mechanical advantage of leverage within the limits of the throw out mechanism. I'd be surprised if the span was precisely 201mm on my bike.) What we are trying to achieve here is the tiniest bit of slack in the mechanism so as to achieve the greatest amount of push in the clutch assembly for the highest degree of dis-engagement between the clutch assembly and the friction disc that transfers motor torque to the transmission input shaft. The free play at the hand lever should be minimal. If the free play is too loose, you would not be getting the maximum dis-engagement when you pull the clutch lever. There is a small window of adjustment where you have your free-play and full disengagement. It is inside that range where you can try to position the clutch take-up where you want it. This range of adjustment is very small.

Actually, you can get the desired free-play using the handlebar end adjuster as long as you don't run out of threads on the adjuster. It's a sort of a "feel" thing.

If there is no slack or free-play, that means that the release mechanism is always pressing on the clutch assembly. This is bad. In a car or truck it would be called riding the clutch if you rest your foot on the clutch pedal and eliminate the free-play. This promotes excessive wear of the friction disc.

Be aware that I am completely self-trained and not a professional airhead mechanic. You might get somewhat different advice from more experienced pros.

If you want to speak with me directly, my cell phone number is 309-251-0877.

James Strickland, IL. Airmarshal
Last edit: 1 month 2 weeks ago by 8053. Reason: clarity?

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1 month 2 weeks ago - 1 month 2 weeks ago #5628 by Wobbly
Replied by Wobbly on topic clutch engages very early

8053 wrote: If there is no slack or free-play, that means that the release mechanism is always pressing on the clutch assembly. This is bad. In a car or truck it would be called riding the clutch if you rest your foot on the clutch pedal and eliminate the free-play. This promotes excessive wear of the friction disc.


You'll need "free play" in both the clutch cable AND the arm when the lever is fully released.

Typically, unless you have short fingers or weak hands, you want the clutch to engage as the lever is almost all the way out. This means the clutch is getting maximum dis-engagement when the clutch lever is pulled in. Failure to fully dis-engage will make the bike want to creep, which may end up walking you into a busy intersection. And we don't want that.

► Tip: For smoother clutch operation do this: 1) Hit the grease nipple on the throw-out arm with a grease gun. 2) Hit the "barrel" where the clutch cable goes into the lever AND the clutch lever pivot bolt with Motul Chain Lube. Click Here

Don't hide 'em, Ride 'em !!
#15150
Last edit: 1 month 2 weeks ago by Wobbly.

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1 month 2 weeks ago #5629 by 8166
Replied by 8166 on topic clutch engages very early
From the Forum Landing Page:
This is NOT the place to post information or questions related to diagnosing problems, wrenching, parts, or technical aspects of airhead motorcycles. The correct place to post it is in the one of the sub-topics of the Airheads Technical category.

So I've moved this topic to the Wrenching category.

There are two aspects to clutch adjustment. The bolt and jamb nut on the back of the transmission are used to set the actuating lever as close to 90° to the long axis of the motorcycle as possible when the lever is pulled forward and starts to encounter resistance from the throwout bearing. This is done to provide the maximum mechanical advantage to the actuation arm. BMW specifies a specific distance, which I don't recall right now but it's somewhere around 210mm, which is set between the clutch cable anchor on the side of the transmission to the barrel at the end of the clutch cable that engages the actuation arm. BMW even suggests that a heavy wire be cut to that length and be used as a gauge. I find it easier to just eyeball when the lever hits the 90° sweet spot, then tighten the jamb nut.

That done, you can then move your attention to the cable adjuster on the handlebar perch. The idea here is to let the rider have some flexibility in where the clutch disk initially starts to disengage, that is, when the fingers on the lever start to feel resistance. The farther out from the handlebar the lever is when the fingers feel resistance, the more clutch disengagement will be achieved by the time the lever hits the bar, but the way the hand is built, your fingers will have less strength when they are straight. On the other hand (no pun intended), the clutch cable must be pulled far enough so that the clutch fully disengages when the lever hits the bar. Otherwise, the clutch will drag when you stop at a light, and you'll also find that the transmission becomes difficult to shift. Also, you MUST ensure that there is at least 1mm or so of slack in the cable, even when the handlebars are turned fully to the right and the left. This is so that the clutch can fully engage, and failing to provide that slack can result in clutch slip. So your job in altering the handlebar adjustment is to find the sweet spot where you can easily initiate the lever pull, yet still sweep the lever through enough tensioned pull to fully disengage the clutch. I find one or two millimeters of slack in the cable works well for my rather small hands. If you find your fingers working too hard, try a turn or two of the adjustor to make the slack a bit larger. But if you start having trouble finding neutral at a traffic light, or the transmission is difficult to shift, decrease the cable slack to get more disengagement of the clutch.

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
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