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Disconcerting whining noise from engine

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Hello all. I have another question about my '81 GS850G (with 17K miles). When it's running, it makes a fairly pronounced "whining" noise that rises and falls with engine speed. It sounds a lot like a supercharger or gear drive on a car. Is this normal, and if not, any guesses about what it is?

There is also an intermittent "clacking" noise that comes from near the clutch. I'm going to open up the clutch cover this weekend to investigate, but anything specific I should be looking for?

Thanks again y'all,

Scott
 
Whining,clacking.... Hmm

have you checked your camchain tensioner? Do you understand how it works?
 
tom203 said:
Whining,clacking.... Hmm

have you checked your camchain tensioner? Do you understand how it works?
Click to expand...

The cam chain tensioner on this bike was leaking when I bought it, so I bought a brand new one - along with a new gasket for it - and had a guy who claimed to be a whiz install it (along with several other things that needed attention). I wasn't able to be with him when he did the work, so I can't vouch for whether he really knew what he was doing, but based on the evidence of this and other tasks (e.g. he failed to install the new gasket), I'd say he's not nearly the mechanic he thinks he is. So if it the cam chain tensioner isn't installed correctly, I wouldn't be surprised.

And no, I really don't understand how they work. I'm all ears.
 
I'd check tensioner myself and know for sure.
The tensioner is so simple that folks often mess it up. Your mechanic might fall into this group. I think on the 850 it's easy to remove,check operation and replace correctly without messing with carbs.

have a look at this link. If you held a tensioner in your hand, you'd probably understand its simplicity in a few minutes. The plunger shaft needs to push out against the chain guide (and not creep back) to take up chain slack or unpleasant things will happen.

http://members.dslextreme.com/users/storagecliff/images/engine_odds-n-ends.html#A05
 
Read that link! Your tensioner basically looks like this pic. The plunger and long spring on right side pushes out against camchain rear guide. It's driven out and held there by that knurled knob/spring gizmo at top. On bottom in pic, there is a lock screw and lock nut to aid in correct reseting and reinstalling should tensioner need servicing. The lock screw must be released (slightly) after reinstalling tensioner in engine or tensioner plunger won't do its job of pushing out!


image.jpg
 
Well folks, after a fair amount of studying its operation, I removed the cam chain tensioner today and sure enough, it had been improperly installed by my "mechanic". The set screw was still tightened up against the plunger, the lock nut was loose, and the big knob on the right was tightened all the way clockwise. So I loosened the set screw 1/2 turn to unlock the plunger, and with pressure from my finger on the end of the plunger, I turned the big knob as far as it would go counter-clockwise, allowing the plunger to recede into the body of the tensioner all the way. I then tightened the set screw to lock the plunger and reinstalled the tensioner (after a little more cleaning and detailing of the back of the engine). After I got it reinstalled, I loosened the set screw 1/2 turn again, and sure enough, I heard the plunger "pop" into place like it's supposed to. I left the set screw where it was and tightened the lock nut to keep it there. And what d'ya know - no more whining noise! Woo hoo!

Several attempts have been made to describe the operation of the tensioner, so here's my version:

The purpose of the set screw is to freeze the plunger in place; it keeps it from sliding either in or out. When you tighten the set screw, it freezes the plunger wherever it is. When you loosen it 3/4 of a turn or less, it allows the plunger to move within a limited range. But if you loosen it more than 3/4 of a turn, it will allow the plunger to come completely out of the tensioner. Sometimes that's good, sometimes that's bad - depending on what you're doing.

The purpose of the big knob on the right is to control how far the plunger recedes into the body of the tensioner when you apply pressure to the end of it. So two things are happening at once: with pressure on the plunger, it will recede into the the body of the tensioner as you turn the big knob counter-clockwise. The big knob will only go so far; when it has reached its maximum, the plunger will be fully recessed into the tensioner. When you reach that point, let go of the big knob and tighten the set screw on the plunger. The big knob is always spring loaded to want to turn itself clockwise, so when you turn it counter-clockwise, you're turning against that spring tension.

I took before and after videos (with sound, of course), and if I can figure out why they won't upload to Youtube, I'll add a link to them on this thread.

So one more step towards making her "right"! I hope all this is helpful to someone. And you "Gurus", if I did anything wrong, don't be afraid to speak up!
 
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Nice bike!
What's the difference between a puppy at the back door and a woman at the back door?
The puppy quits whining when you let it in.
 
bonanzadave said:
Nice looking 850. And it sounds good too !
Click to expand...

Thanks. You ain't seen nothin' yet. I'm slowly but surely putting her back like she started out. There's a lot of touch-up to do on the frame (lots of chips from stones and such). I also have a much closer-to-new seat to put on, complete with the chrome strips (and blue tape inserts), and the correct passenger grab bar - when the mechanics are sorted. This weekend I fixed the noisy cam chain tensioner and tightened the big 32mm nut on the clutch basket. Next weekend is the valves. Then the carbs. I'm detailing stuff as I go, so it's gonna be nice by summer.

Watch this space....
 
Now that you have discovered that you are the best mechanic for your bike, when you remove the cam cover to do those valve checks, have a look (if possible) at rear chain guide in case it was tortured by the tensioner error. Might as well check camshaft to crankshaft timing to know it's perfect.
 
tom203 said:
Now that you have discovered that you are the best mechanic for your bike, when you remove the cam cover to do those valve checks, have a look (if possible) at rear chain guide in case it was tortured by the tensioner error. Might as well check camshaft to crankshaft timing to know it's perfect.
Click to expand...

Hi Tom. Yes, I think I have discovered that I am the best mechanic for my bike - at least until it comes time to go into the engine. But I don't expect to ever have to do that; the bike only has 17K miles on it and seems pretty tight (in a good way). I don't ride much, and when I do, I ride pretty conservatively.

Those two suggestions both sound like good ideas. I'll look as much as I can without disassembling anything any further than is required for doing the valves. Also.... if the camshaft-to-crankshaft timing were off (even a little bit), wouldn't it be really noticeable? The bike runs pretty well right now - except for the carb issues.
 
Blue Falcon said:
did tightening the nut get rid of the rattle?
Click to expand...

Inconclusive. It seems to have helped, but there are two factors that are keeping me from saying it fixed it.

1) I wasn't able to tighten the nut to the specified torque because I don't have the proper tool to hold the clutch still as I tighten it. It's certainly not finger loose any more like it had been though.
2) all six springs were below spec so I ordered a set of new OEM springs for it, but they haven't arrived yet.

After I get everything buttoned up the way it's supposed to be, I'll add another post to let everyone know the results.
 
MI GS850G guy said:
Inconclusive. It seems to have helped, but there are two factors that are keeping me from saying it fixed it.

1) I wasn't able to tighten the nut to the specified torque because I don't have the proper tool to hold the clutch still as I tighten it. It's certainly not finger loose any more like it had been though.
2) all six springs were below spec so I ordered a set of new OEM springs for it, but they haven't arrived yet.

After I get everything buttoned up the way it's supposed to be, I'll add another post to let everyone know the results.
Click to expand...

Do you have a sound byte of the clutch rattle. The sound coming from my clutch is like a hollow pingy/clinky sound. Kind of like lightly tapping an aluminum wrench against one of the covers. I had someone PM me it's piston slap, but the sound does not come from the buckets, it comes from the lower back right end...stethoscope. I have no compression loss, no power loss, no performance issues and it only starts from 4k rpm while rolling, won't do it sitting still, had to lift the bike and roll the back wheel to narrow down sound area. I am thinking springs and nut for me too... from what I understand, it's more of an annoyance than anything. Just wanting to see if our sounds are similar. Can't tell from your videos.
 
I had my stator screws come just a little loose and it made a whining sound, just a thought, I later used Loctite on them after that.
 
850 Combat said:
Badly synched carbs can cause a rattle in the primary gears.
Click to expand...

I'm pretty sure I have my carbs pretty well bench synched, but I have not done a vacuum sync yet because they need to be gone back through to do a thorough cleaning/jetting/etc. With that in mind, do you still think they could be the cause of my rattling?
 
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