Lower-end noise from my GS850 daily driver

[CSaddict]

Im very curious on the out come of this. Mine makes a knock at idle as well but disappears at higher rpm and has plenty of power. Mine sounds like its coming from the trans.

[megatwin]

Just curious,when you had the rotor off,did you try lifting the end of the crankshaft to see if you could detect any movement?
Same with the trans input shaft?

[Roostabunny]

Sorry to report that this issue has been on hold this whole time. Nothing done.

I bought a cage for the first time in 7 years, because I had worn out my welcome on loaner DD's. Course I bought my long-time dream car, a 1991 Toyota Land Cruiser. Needless to say, now both my dd and my backup are projects, and life's been throwing too many curve balls to keep the Toyota running and get the GS back on the road.

But aside from the nice weather, the gas bill on Toyota (and I knew about that before I bought it) means I'm pretty anxious to get back to work and back riding. Travel plans and such means it may be another 2-3 weeks before there's an update, but next step is still pull the clutch, replace the cover, and run it for a few seconds to see if the noise goes away.

Actually, the next step is "get her started", which is my fault. Seven years of riding all winter, I never thought she'd ever ever sit this long!

[londonboards]

I'm sure you know this by now but I couldn't find a post on here that describes it.

In one of your photos and the hand drawn diagram above, you show movement between the outer clutch basket and the gear that is attached to it. This is what those springs are on the back of the clutch basket. They are supposed to cushion the power being transferred from crank to clutch. The crank gear will turn the clutch basket gear which will turn the clutch basket after the 1/4 - 1/2 inch slack has been absorbed by those springs. Those springs, particularly the fat ones, get compressed over time and consequently rattle in their sockets. The only way to fix this is to grind off the big rivets and put in new springs and weld the basket up again.

The big question is; does the rattling of these springs cause the noise problem that you have? You can test this by running the engine, taking off the oil filler cap, engaging first gear and just lightly letting out the clutch and holding it just where it bites. This should take the slack out of the clutch basket springs and if that is the cause of the rattle, the noise should diminish.

I have 2 GS1100Gs and both clutches are out at the moment. See my posting on clutch rattle here:

http://www.thegsresources.com/_forum/showthread.php?p=1989964#poststop

I have been battling this problem for ages.

My current view (my view changes as I eliminate reasons for the rattle) is that there is (as you have shown) some movement of the complete clutch along the drive shaft. I have read somewhere on here, that this movement can be because the spacer that the clutch basket sits on is fractionally wider than the clutch basket itself. So no matter how hard you tighten the clutch hub nut, whole thing will still move. If this was the case, then it would stand to reason, that one of the tests you see being applied to this noise, namely running the bike and pulling the clutch in to see if the noise goes away, will not work. In my case the noise does not go away when you do this but it changes pitch somewhat. This leads me to believe that this movement is the result of lateral play of the basket on the shaft. When the clutch is pulled in it simply allows a little more movement and therefore a different tone to the noise. However when the engine is revved up, for me at least, much of the noise goes away. Somehow I have convinced myself that this would happen if it was lateral movement. I assume at higher and smoother revolutions this lateral play would not occur or at least not rattle.

I do believe someone on here even had their spacer ground down somewhat to eliminate this problem and all their noise issues went away. I have also been told that if this component was ground down, it's strength would be compromised and this should therefore not be attempted.

At the end of the day, with tons of advice from very learned mechanics and engineers, I have reached the conclusion that the noise is not conveying any message of impending doom and it is best ignored. Don't take the oil filler cap off and you won't hear it. Rev the bike up and it's gone. I am going to try this approach for this summer at least!

Good luck with yours.

Greetings

[exdirtbiker]

I have reached the conclusion that the noise is not conveying any message of impending doom and it is best ignored.

But... if we all did that, this forum would dry up and die in a week !!!

[Roostabunny]

But... if we all did that, this forum would dry up and die in a week !!!

Ha! Well said.

[Roostabunny]

The big question is; does the rattling of these springs cause the noise problem that you have? You can test this by running the engine, taking off the oil filler cap, engaging first gear and just lightly letting out the clutch and holding it just where it bites. This should take the slack out of the clutch basket springs and if that is the cause of the rattle, the noise should diminish.

I'm going to check this out. I'm actually still kind of hoping it's clutch rattle, but couldn't prove it to my own satisfaction. Your thread was terrific, and the youtube vid was the best comparison I've had access to. It's been so long since I've heard the sound on mine though...

Just never thought to try popping out the oil fill cap to listen.

Questions for you - did you feel that vibration all the way up through the bars? No reason you shouldn't, I guess, but I'm curious about your experience.

And you mentioned letting the clutch out till it just bites to test the noise - do you feel/hear the rattle at cruising speed with the clutch lever fully released?

[londonboards]

Roostabunny - no I do not feel any more vibration than I have experienced riding any of these bikes over 30 years. I always feel a bad vibe patch somewhere around 3,750 to 4,250 revs but it is never intrusive. No it seems to me that all this clutch noise simply goes away when the bike is ridden or revved highly which comforts me when I am cruising at 80 mph on the highway. Obviously difficult to hear anything at speed.

If you are still not clear where this noise is coming from you can narrow down the area by using a doctors stethoscope device to listen to different parts of the motor when it is spinning. Or you can do what I do. Take a 2 foot piece of 1" x 2" timber. Put one end firmly on any part of the engine whilst it is running and put the other end firmly on the ear bone (or on the little flap in the centre of the ear). You will hear every single thing. Listen to other motors to compare sounds. You can eliminate cam chain thrash, cam shaft bearing problems and a host of other potential noise producing problems like this.

And never underestimate the potential of a good carb sync to eliminate a lot of engine rattle. Just having one cylinder slightly out can make the motor sound like the whole big end is shot and about to explode.

[Roostabunny]

Roostabunny - no I do not feel any more vibration than I have experienced riding any of these bikes over 30 years. I always feel a bad vibe patch somewhere around 3,750 to 4,250 revs but it is never intrusive. No it seems to me that all this clutch noise simply goes away when the bike is ridden or revved highly which comforts me when I am cruising at 80 mph on the highway. Obviously difficult to hear anything at speed.

If you are still not clear where this noise is coming from you can narrow down the area by using a doctors stethoscope device to listen to different parts of the motor when it is spinning. Or you can do what I do. Take a 2 foot piece of 1" x 2" timber. Put one end firmly on any part of the engine whilst it is running and put the other end firmly on the ear bone (or on the little flap in the centre of the ear). You will hear every single thing. Listen to other motors to compare sounds. You can eliminate cam chain thrash, cam shaft bearing problems and a host of other potential noise producing problems like this.

And never underestimate the potential of a good carb sync to eliminate a lot of engine rattle. Just having one cylinder slightly out can make the motor sound like the whole big end is shot and about to explode.

I bought a cheap mechanic's stethoscope, but I think my ear needs training - every location sounded the same to me. I'll pull it out again, might have more success now that I've had a few months to calm down. Just wish I had some other GS's to listen to.

I'm a semi-obsessive sync-er, but that was and still is on the list of things to check. A recent pre-noise repair was fixing an intake leak from a munched airbox boot and aging weatherstripping (from my original airbox rehab). BUT, I have to think that a sync was on my list prior to complete re-assembly on that job. I just don't remember.

[londonboards]

Not sure if you will get the low end (low frequency) rumbles with a stethoscope. Try the piece of wood trick. Push hard against the ear bone. You can hear and feel it all at the same time.

Greetings

[Roostabunny]

Not sure if you will get the low end (low frequency) rumbles with a stethoscope. Try the piece of wood trick. Push hard against the ear bone. You can hear and feel it all at the same time.

Greetings

Isn't that a scene in Mr. Holland's Opus?

Seriously, though, I will try the stick. I did notice that the sound through the scope seems to be all piercing high frequency stuff.

[Roostabunny]

Not sure if you will get the low end (low frequency) rumbles with a stethoscope. Try the piece of wood trick. Push hard against the ear bone. You can hear and feel it all at the same time.

Greetings

This was pretty brilliant - felt like the sound quality was much better with this...



...than with the actual tool (stethoscope).

And I hate to admit it with me calling this a lower-end noise in the first place, but it's prompting me in a different direction. Guess I'd rather fix the bike than feed my ego, so... we'll follow the new data.

First off, I obviously got the bike running. Checked for spark (yes), then drained the #1 carb bowl as I suspected excess buildup from sitting on the side stand for months. Anyway, with a little help from the battery on my Land Cruiser it eventually caught, and with a minor idle speed adjustment warmed up and ran.

First thing I did was take the oil cap off. There was no noticeable difference in sound volume or tone - makes me suspect it's not the clutch.

Then I start with the wooden stick working my way up...
Clutch area - I can hear the tap but not feel it.
Crank/ignition area - seemed a bit louder but still not dramatic
Fins - Not a lot, but might not be enough contact area to get good resonance
Rear of Cam cover (on trim cap) - noticeably louder tapping, some feel through the wood
Front Cam cover (on trim cap) - even louder, felt the tapping distinctly through the wood

I'm still not very confident with this method of troubleshooting, but I did feel like the tapping was more distinct on the right side than the left.

My instinct is to get the cam cover off again and inspect.

Am I crazy not to follow through on pulling the clutch out again and running for a few seconds with no clutch just to eliminate that possibility? Or is the lack of additional volue with the oil cap off enough to say "nope, not the clutch"?

[londonboards]

Glad you got on well with the piece of timber.

Looks like you do not have a clutch problem. Especially as you don't get an increase in noise with the oil filler cap removed.

A noise like that on the top of the engine could well be cam end float. This is the cam shaft moving sideways and knocking. There are plenty of threads on this. It is complicated to eliminate and apparently the noise is innocuous and can be ignored. I think there are various symptoms associated with it too. Such as it comes and goes with different engine temperatures. So you might find your noise goes away as the engine warms up but comes back when it is very hot.

I don't think you need to run the bike with no clutch to eliminate that as a noise source. Putting the bike in gear and letting the clutch out until it bites (with the engine running) should tighten up anything rattling down there. If the noise goes when you do that, then have another look at the clutch.

Greetings

[azr]

If it's cam travel the noise should go away when you bring the idle up to 2000 rpm or more. If it is that you can just get used to it and ignore it for the life of the bike. Lots of these bikes have it. There's plenty of YouTube videos describing it as well.

[Roostabunny]

Did a closer inspection of the valve train last weekend but didn't see anything noteworthy. I was hoping again to find something out of place or obviously loose, but no.

Edit: I specifically didn't notice any side-play on the camshafts, but not sure if pushing on them by hand is enough to determine.

I'm wondering if...
1.) there's additional troubleshooting I can do without removing the head
2.) if removing the head is even likely to reveal anything
3.) and if I do, what I might look for.

At this point she idles good and plugs seem OK. Bogs a little off idle, but that's new, probably due to too long sitting.

I'm trying not to get discouraged, wish I had a local expert (like I used to in Phoenix) as diagnosing a sound over the internet is obviously pretty tough. I miss riding, but I'm afraid I'll blow her to bits, which isn't much fun or a very safe way to ride.

Another EDIT: Just a question as I keep my options open, best source for OEM base and head gaskets? I'm inclined to go with Z1 if they sell OEM, just checking. And is there anything else I want to do/replace while apart if I do remove the head?