odd shifting issue with GR650

[Guest]

I just wanted everyone's opinion on a shifting issue I'm experiencing with my '83 GR650. I recently rebuilt the engine after I found out that a connecting rod bearing had come loose and caused some damage.

With the engine apart, I never messed with the shift forks and the transmission, I just left them sitting in the bottom of the engine case as I did the rebuild. I did pull the clutch apart. The friction plates were soaked in oil the whole time they were out of the bike. I put everything back together again per the manual. The bike restarted the first try and everything seemed to run ok.

But I'm having issues with the shift lever. For some odd reason it seems as if it shifts just fine if the bike is running around 3,000 rpm's or higher. If I keep the engine at less than 3,000 rpm's, the foot shifter seems real hard to push up into the higher gears. And forget putting it into neutral if the engines running. However, turn the motor off and it finds neutral just as slick as can be with no effort...?? It almost seems as if it has something to do with the speed of the oil pump...maybe?... as odd as that may sound.

I have tried adjusting the clutch cable at the push rod. The manual says to turn the adjusting screw .."until it feels high resistance to turning and then back it off 1/4 to 1/2 a turn, then tighten the nut." Somewhere else on the forum here someone mentioned to only turn the adjusting screw until you just begin to feel resistance and then back it off. Could I possibly be tightening the adjusting screw too much?

Thanks for the help.

 

[Agemax]

make sure the drive chain is tensioned and lubricated correctly, and not badly worn out. this can sometimes cause shifting issues. (worth a look anyway!)

 

[bwringer]

I have tried adjusting the clutch cable at the push rod. The manual says to turn the adjusting screw .."until it feels high resistance to turning and then back it off 1/4 to 1/2 a turn, then tighten the nut." Somewhere else on the forum here someone mentioned to only turn the adjusting screw until you just begin to feel resistance and then back it off. Could I possibly be tightening the adjusting screw too much?

Thanks for the help.

Yes, you'll want to experiment with this adjustment. Takes just a few minutes and don't cost nuthin'... Getting the right feel takes a few tries.

You may also benefit from removing the ramp mechanism (the widget you're adjusting), cleaning out the ancient dried remains of the original scraps of earwax grease, and greasing it. Take photos so you get it right when you re-assemble.


Two other potential issues I'll bring up as outside possibilities, or at least things to check:

1) Some aftermarket case gaskets are too thin and can cause odd problems with binding the shift lever shaft.

2) Make sure the return spring for the shift lever shaft is in the correct position. I don't think this is your problem, since the bike is rideable, but if the shift lever doesn't spring back and it's not binding, you might want to check this.

 

[Guest]

Agemax... all new sprockets and chain so this shouldn't be an issue. But I can see where this could be an issue. I'll recheck it.

Bwringer...all good points. I haven't touched the ramp mechanism so this could be an issue. I'll give it a good once over.

I used OEM case gaskets so I think I'm good there.

I'll double check the shift lever just to be sure.

Thanks for all the help.

 

[oldrookie]

Super,
You got it running! Not sure how I missed this thread. Good to hear you are dealing with something other than the bearings. It's still a problem, but at least it is a different problem.

 

[Chuck78]

There is also the centrifugally clutching flywheel that releases it's spinning mass at mid and higher rpm's, flywheel weight's clutch is engaged at lower rpm's to add extra mass to the rotating assembly at lower speeds to give greater low end torque but still allow the engine to spin freely at higher rpm's to add high rpm performance. I wonder if that could have any effect on the shifting whatsoever?

My wife's gr650 is having the same problem, she directed me to this thread today. Did you ever get it fixed?

She said her clutch felt different, like it got looser when it started acting up. I suspected, same as every friends' bikes that I have gotten my hands on, that the clutch linkage actuation mechanism was adjusted wrong.

She said it was leaking oil around the shifter all of the sudden, so I suspected this even more. You basically clean out and regrease the helical worm gear mechanism, reasemble, and with the cable adjustments very loose (turn adjusters in all the way), turn in the pushrod actuator screw or assembly until you feel it touching the clutch pushrod to the clutch basket on the other side of the engine. Then back it out 1/4 turn or so and hold it steady in place while you tighten down the locknut on it. Then you adjust your cable to have 1-2mm of free play in itself. This keeps everything good while steering the bike, no unexpected cable housing binds causing the cable to tighten itself beyond freeplay. Then the clutch adjustment is good.

If improperly adjusted, the pushrod that goes through the engine will spin with the clutch basket nonstop. Her GS550 was like this when I first worked on it, and it had gone on so long that the pushrod seal in the chain case area had grooved out the steel pushrod shaft! Also this can allow the clutch to slip slightly at all times if there is no free play in the pushrod mechanism, which can wear down the friction linings and even potentially warp the steel clutch pack plates. Warped plates will cause shifting problems. Suzuki says use a feeler gauge with each plate on a nice flat sheet of modern glass (like window glass or glass tabletops, very flat surface) and check each plate for warpage.

She said her shifting took much more effort at lower rpm's all of the sudden, and the clutch lever feel got extra loose.

 

[Chuck78]

On a good running bike with this shift dog type transmission, you can very easily up shift without clutching at all, just put a little pressure on the shifter but not enough to force it, and at the desired shift point, just blip the throttle back momentarily and the shift drum will rotate the rest of the way and slide the gears over on the shafts with the shift forks. So the clutch being engaged or disengaged on a healthy bike won't make a difference. Warped clutch pack plates or maybe worn out roller bearings on the clutch basket may play havoc here though.

If this is happening in all gears, I doubt all three shift forks got worn/bent simultaneously, same with the gears on the gearbox shafts, so that area is unlikely a suspect.

I'm leaning towards improper clutch adjustment caused excessive clutch slippage on the long haul 500+miles from Barber Vintage Festival to the middle of Florida, where the bike is sitting for now. Worn friction material, probably warped steel clutch plates, as I have been told that these being warped will definitely cause odd shifting issues.

Since the shift drum rides on the same type of roller bearings that the high rpm rotating parts of the engine ride on, I highly doubt that the bearings have excessive wear enough to cause slop enough to affect the shifting drastically, as the shift drum bearings only move with the shift pedal/drum, and only 1/4 or 1/2 turn at a time. Only a serious lay-down wreck on the left side could really do much damage to the shifter shaft/drum outer bearing.

I still have no theory on how the clutching centrifugal weights could be malfunctioning and making the shifting suffer, but I wouldn't completely rule that out. That is a feature exclusive to the GR650 only, no GS's or any other bikes to my knowledge had that, and I have never heard of one causing ANY problems.

Big Rich in PA has had 2 GR650's for many years, maybe he can chime in if he has anything to add.

 

[Big Rich]

I dunno.... but shouldn't the clutch pushrod (and therefore entire clutch mechanism) disengage the clutch regardless of what the flywheel is doing?

Super / Chuck: I would try adjusting the clutch so it acts accordingly under 3k rpm, and see if it is slipping at higher rpm (by using gearingcommander.com).

 

[Chuck78]

If the clutch was slipping and the steel plates got warped, the clutch would not be easy to fully disengage, therefore may cause some odd behavior.

Wife sez:
no, clutch lever loose and extra cable slack, shift lever not moving in the same way OP describes. Clutch loose, shifter lever tight/difficult to move

 

[Gorminrider]

possibly a problem with parts 7, 22, and the thrust bearings 16,17? parts missing? something jamming?
http://www.cmsnl.com/suzuki-gr650-x-tempter-1983-usa_model15987/partslist/94164.html#results

I'm no expert-I'm just postulating but...seeing as I don't see anything special about your clutch in the above .
When you squeeze the clutch hand lever, the spring-back is almost direct from the clutch cage springs, so it's pretty easy to tell if the clutch is being pushed against.
your main adjustment is just presetting the adjustment bolt against that pushrod. as said already, It just needs some slack to ensure that the clutch springs are doing their whole job holding the plates together to grip..and it pushes the clutch apart against the clutch springs to allow the clutch plates to slip while you shift.
The tricky part is minimising it so you can enough travel to get the clutch to dis-engage. -a compromise of leverageversus rider comfort on these older bikes.

It's pretty common for a fresh-assembled bike to have a sticky clutch, oily or not, it takes awhile to break them in saturate em I think.
One peculiar idea I've had is to put some thin washers on the clutch cage assembly bolts (part 14) on top of the "towers" (part 3) and then torque the bolts to spec...such that the cage is a little wider for a period of time, but I've never tried it.