Another attempt at reducing clutch drag to a minimum

[tirebiter]

Here I go again. I have read that clutch drag issues on these bikes can likely be caused by using the wrong engine oil. I have read that it also can be caused by a weak clutch cable, grooves worn into the edges of the clutch basket prongs, warped driven clutch plates, worn out clutch release pinion/shaft bearing ... am I missing any other likely reasons ?

One thing I can easily determine by measuring is how far the release arm/lever at the clutch cover, moves. Has anyone with a clutch that does NOT drag ever measured the distance the clutch release lever/arm end moves. I'm referring to the end of the release lever where the clutch cable is attached to it by a pin, down at the clutch cover. I'm intersted in knowing exactly how far the centerline of said pin is supposed to travel from when the clutch operating lever - on the handlebar - is out all the way until it is pulled in all the way.

I believe mine moves enough but I have nothing to compare it to. If indeed the travel on mine is the same as a known non-dragging clutch bike, then I know my cable is good.

One thing I have noticed is the clutch basket has what seems to be an excessive amount of lateral freeplay along the primary shaft. I have not measured it but it seems to be in the 1/32" to 1/16" range or more.

Even when fully warmed up there is a noticeable clunk when putting the bike in gear. When cold it's usually very difficult to shift. I cannot imagine the amount of clutch drag I'm experiencing is supposed to be this much. I recently drove a ten year newer non-Suzuki and there was absolutely 100% zero drag at idle. No clunk when I put it into gear at full stop with the engine running. Are these older GS bikes not as well designed as far as the clutch release mechanism goes ?

 

[wymple]

Misadjustment or a worn clutch basket, those grooves, are the most common issues. I've never heard of wrong oil making a clutch drag. It will make a clutch slip.

 

[tirebiter]

Thanks Wymple. I'll be taking the clutch out - yet again - in the next day or two to do some more careful looking at everything. Replacing the clutch plates made no difference.

 

[Rob S.]

Cold, engine off (I don't think that makes a difference though), mine travels one half inch, and everything works perfectly.

PS At lights, mine makes a nice 'clunk' dropping her into first. I think that's normal.

 

[tom203]

Cold, engine off (I don't think that makes a difference though), mine travels one half inch, and everything works perfectly.

PS At lights, mine makes a nice 'clunk' dropping her into first. I think that's normal.

My 650 has similar half inch travel,makes good clunk into first when cold, less when warm. Clutch cable free play increases slightly when hot- I noticed this more with new clutch cable than old one.

 

[Guest]

Misadjustment or a worn clutch basket, those grooves, are the most common issues. I've never heard of wrong oil making a clutch drag. It will make a clutch slip.

Too heavy of an oil well make it drag. A 20w-50 well drag way more then a comparable 10w-40. As far as making a clutch slip, the energy conserving oils tend to be the problem there.

 

[tirebiter]

Had a chance to pull the clutch and make a more careful assessment of all the parts. When I put different (used) clutch plates ( previous post) I had stupidly put the wrong metal ones in. Two were slightly blued and I thought I put in the correct stack ... oops ! No excuse except it was late.

Discovered my error yesterday. The basket has some polishing from the edges of the fiber clutch plates. The inner has some polishing from the teeth inside the metal plates. ABSOLUTELY ZERO appreciable wear on these pieces !!!

Replaced it all with a good used, complete assembly. It also has no appreciable wear. Slight polishing but not a measurable reduction in material thickness. Less than 0.0001" (one ten thousandths of an inch) according to my expensive Starret vernier caliper. This time, I made sure I did not mix up the plates again.

Handily I used a portable engine hoist to lean the bike WAY over onto a block of wood underneath the kickstand mount. I did not have to drain the oil this time and everything was easier to work on. I'll have to take a picture when I utilize the hoist again.

The result is a clutch handle that feels like it's broken as compared to before. Almost no resistance to pull the handle all the way into the grip. I had nothing to compare it too before now. It even feels like it makes a slight "pop" - it suddenly gets even easier to pull - at the point where the clutch disengages.

There is 1mm of freeplay at the release arm down on the clutch/engine cover. The clutch does not slip at ANY RPM - in 3rd gear anyway. Pushed the speed limit up a steep hill to test. Shifted out of 3rd, full throttle, at a conservative 8500 RPM and tried to make the clutch slip by easing the handle out still at full throttle going into 4th gear - but it grabbed tight ! No clutch slip.

When cold there is the slightest hint of drag and a quiet little clunk when shifting into gear at a stop. Before it's even fully warmed up, the clunk gives way to a "snick".

While rolling (cold or warm) the ease of shifting is like a dream and nearly 100% silent. Once I get used to it all over again, I may notice some lesser problems but for now I am greatly relieved and satisfied that the transmission's shifting mechanism will not be tortured anymore.

Thanks again for all the good help I have received from this forum. Think I'll go out for a ride right now.