GS850GN (1979) Sticking clutch

[Tijmen]

Hi all,

I am having some trouble with a GS850G from 1979 (N). The clutch does not want to disengage properly it seems. The problems being that I cannot get into neutral whilst the engine runs, the RPMs drop when I get into a non neutral gear whilst standing still and the general shifting experience being noisy and troublesome.

Background
This bike has been standing still for at least 10 years, 20 years at maximum. Its engine was completely drained of oil and all of the parts were removed except for the wheels, drivetrain, front suspension and some leftover wiring bits and pieces. The previous owner/restorer seems to have been over his head judging by the severely botched wiring jobs. I cannot ascertain whether this man/woman has also attempted engine repairs (I hope not). I've been putting everything back on it in the past half year. It has received fresh 10w40 motorcycle engine oil, a new oil filter, adjusted valve shims, a new stator and a new rectifier. The clutch has always been sticky and troublesome since I my first test drives with the bike.

On first inspection the clutch showed blued plates but practically new friction plates. These new friction plates are not factory original. The clutch cable was easily adjusted, but had to be over-tightened severely in order to get some kind of usuable clutch disengagement.

What have I done to the clutch

1. I have replaced the clutch springs for new ones and removed extra shims that were present on top of the old springs
2. I have replaced the clutch pack with a second hand one
3. I have bathed the clutch friction plates in oil before mounting
4. I have torqued the clutch springs in a cross pattern in a gradual manner

How do I adjust the clutch?
This is after reassembling the clutch and remounting the clutch cover. The clutch cable has been completely disconnected from the bike except at the handle bar.

1. I turn the protruding axle with splines from the clutch cover in a anti clockwise manner to make it engage
2. I tighten all the spacing mechanisms present in the clutch cable in order to create maximum slack
3. I connect the clutch to the engine block by threading it all the way into its insert present next to the clutch cover, on the engine block
4. I connect the end of the clutch cable piece to the axle with splines, usually it ending up at around the 2 o' clock position as seen from the driver (4 o' clock from the person doing the clutch job, facing the clutch head on)
5. I remove the initial clutch cable slack by threading out the clutch cable slightly at the insert
6. I adjust the free play by reducing the slack at the clutch handle adjuster

Observations

1. When the clutch cable is over tightened and the the bike is put in a high gear (4, 5) the clutch does seem to break free when the rear wheel is kept still. It usually starts sticking again once in a lower gear or after passing neutral.

I'd be happy to hear any comments or suggestions, I am a bit stumped as to what this could be causing. I am starting to think the clutch assembly is missing spacers and or other parts... The pack and spring assemblies I have verified by using an exploded view as reference (hence I found the surplus spacers between the spring and bolts).

[Grimly]

Two things strike me.
1. The 2 o'clock position of the short clutch arm on mine is more like 1 o'clock.
2. No mention of de-burring the fingers of the basket. On my 79 that was a real problem at high mileage. Once done, the problem went away.

[Tijmen]

Two things strike me.
1. The 2 o'clock position of the short clutch arm on mine is more like 1 o'clock.
2. No mention of de-burring the fingers of the basket. On my 79 that was a real problem at high mileage. Once done, the problem went away.

1) I'm probably connecting it a bit too far out. My idea was to get as much travel potential as possible. On my GS650GL it is at around 1 o' clock as well.
2) Good call, I'm going to give that a shot and see. Might as well take a few pictures for the folks here to judge.

[Tijmen]

Two things strike me.
2. No mention of de-burring the fingers of the basket. On my 79 that was a real problem at high mileage. Once done, the problem went away.

The outer and inner parts of the clutch basket feel smooth. Noticeable wear however visually. I'll run a light sand over them to make sure I did not miss any burrs there.

Steel plate splines (fingers?) are indeed a little rough, I'll file those down to make them smoother, knock the sharp edge off.

Rest of the clutch looks normal to me, I'll make sure once again to cross reference the exploded view with that I have making sure nothing is missing. Hopefully it will be a while before I will have to disassemble this clutch again

I'll update this post in a few hours..

Edit: The inner clutch "base" with the splines on it had a surprising amount of burrs around the impact marks. Cleaned it off with some sandpaper grit 600 wrapped around a small screwdriver. Standing still I could now get the bike whilst running through the gears, but still not in neutral. This was already a big gain over the previous situation where I could not get from 1st to 2nd without a lot of force.

Next I had a test drive with lots of cornering, shifting and a nice cruising speed of 60mph. After about 20 miles the bike had completely transformed from a rough shifting hunk of aluminium to a surprisingly easy riding Jap.

After verifying the clutch operation on the middle stand (clutch in, shift into gear, no rear wheel spin) I went ahead and practiced some figure eights and such in a parking lot. Turns out the throttle response in the first few degrees is out of whack. The bike sputters and either dies or picks up.

Anyhow, I am very happy with the results. Thanks a bunch for the tip Grimly, seems to have done the trick! Getting the carburettors back in shape is fortunately a lot better documented in my manual. Here's to getting it right with it

Before:
P1020452_s.jpg

[Tijmen]

After

[Tijmen]

One last update: I put all the set screws back to factory (air screw, stationary screw). Warmed the bike up, synchronized the carbs using the tumblers. Feels like a new bike. Very recognizable low end Suzuki torque and a nice kick in the butt at 5000+ RPM. Lets see if I can get a better mileage than 25 MPG