'82 GS450 Engine Chatter - Cam Related?

[VGplay]

Hi everyone, my GS450 was running very well (I guess it still kinda does, fires right up and will run and rev while making this chatter) and then it started a very loud and tactile ticking when running. Definitely sounds like it is coming from the head/cams and it causes the cam chain tensioner to go crazy. When it first began, wiggling the tach cable stopped the chatter to allow for an afternoon ride. Then I had it start in the middle of a ride where I had to pull over and wiggle the cable before continuing. Now no amount of wiggling allows the bike to run normally.

I first suspected maybe the tach gear was binding but it checked out fine. I pulled the valve cover off and didn't see anything obviously wrong. Though in hindsight I should've manually turned the crank while the cover was off, might've been able to feel something. A guy on the Facebook group suggested re-torquing the camshaft clamp bolts, unfortunately that didn't make a difference. I also removed and reset the tensioner. Curious if anyone has an idea on where to go from here.

I have two videos from when wiggling the tach cable made a difference. The first is of the chatter on a cold start. The second shows wiggling the tach cable and the bike starting and sounding normally.

https://drive.google.com/file/d/1r_PIgr84Q4cpwozgfGua0hn7l01y_f2S/view?usp=sharing

https://drive.google.com/file/d/1gMwT3Y1yCHHgh0uodcsaDtJL_tjsaYex/view?usp=sharing

I appreciate any help and input!

 

[roeme]

Form the described symptoms, it's almost sure that the tach gear (both on cam and the gear itself), tach cable or combination thereof must be the culprit.

Remove valve cover, inspect thoroughly, take pictures and put them into this thread.

Also note that any of the parts number 19 to 22 on the respective parts fiche are suspect (hotlinking picture from https://www.cmsnl.com/suzuki-gs450e-1982-z2-general-export-e01_model13435/partslist/FIG3.html, not sure if it works):

 

[VGplay]

Something with the tach gear makes sense but when I disassembled it nothing looked scored or gave an indication of something being off. It came apart no problem (once I pried loose #20 on the fiche from the head, that was pretty stubborn) and everything fit back together without a fight. I should mention that I did replace the oil seal while looking at it. I didn't get pictures of everything while it was apart, but here is the gear removed.

I probably should've waited another week or so to post this thread, won't have time to take the valve cover off until maybe next weekend. Thanks for the thoughts, I'll update this thread with some pictures of the cover removed when I have a chance.

 

[Guest]

The cam gear is softer than the driven gear. If you try to install the exhaust cam with the tach drive installed, the cam gear can get munched if it doesn't mesh right. Make sure the engine gets turned two revolutions and examine the full cam gear as it goes by.

If this is the problem then you don't have any options but to replace the cam. I know it happens because I've been a victim of my own carelessness in this regard. If the problem was the cable itself I'd think it would be broken by now.

 

[roeme]

(...)

If this is the problem then you don't have any options but to replace the cam. (...)

Well, one option would be to temporarily forego RPM indication and plug the hole.

 

[Gorminrider]

haha! ^^Yes. Tachometers aren't awfully useful anyways unless perhaps you're deaf. Speedos-you need. Tachs you don't.

But that gear looks ok. What I don't get is your timing chain "going crazy"..

and then it started a very loud and tactile ticking when running. Definitely sounds like it is coming from the head/cams and it causes the cam chain tensioner to go crazy.

I don't see an indication that your tach caused it and I am seriously wondering where the tensioner is "at" after viewing the 1st video. It is NOT supposed to do that.

 

[roeme]

haha! ^^Yes. Tachometers aren't awfully useful anyways unless perhaps you're deaf. Speedos-you need. Tachs you don't.

But that gear looks ok. What I don't get is your timing chain "going crazy".. I don't see an indication that your tach caused it and I am seriously wondering where the tensioner is "at" after viewing the 1st video. It is NOT supposed to do that.

Hmmm, you think by wiggling the cable he artificially tensioned the timing chain, and then the whole system went into just the right resonance equilibrium? Or that was just the right amount of resistance to whack the tensioner back into proper operation?

Hmmm. I'd first try to conclusively rule out the tach gear. Note that the tach gear picture is from _before_ he put the engine back together.

 

[Grimly]

Hmmm, you think by wiggling the cable he artificially tensioned the timing chain, and then the whole system went into just the right resonance equilibrium? Or that was just the right amount of resistance to whack the tensioner back into proper operation?

It sounds crazy, but I think you might just have something there.

 

[Gorminrider]

Hmmm, you think by wiggling the cable he artificially tensioned the timing chain, and then the whole system went into just the right resonance equilibrium? Or that was just the right amount of resistance to whack the tensioner back into proper operation?

Hmmm. I'd first try to conclusively rule out the tach gear. Note that the tach gear picture is from _before_ he put the engine back together.

Did you see the video?

 

[roeme]

Did you see the video?

Yes, what about it? It's exactly why I'm a bit stumped that by merely wiggling the tach cable the issue (apparently) went away.

But also, this could've been sheer coincidence, forgot to take this into account.

 

[Gorminrider]

I'm thinking the tensioner is a bigger problem than peculiarities of the tach. I couldn't see much of anything about anything in the second video..I hate these anyways. People spend 30 seconds starting the bike and then jerk the camera all around at various places for a few seconds after. What's so "obvious" and plain to them is never so to me.

 

[GregT]

I'd pick it's a tensioner problem. The twins have uneven pulls on the camchain and any slack is readily heard.
If the tensioner isn't locking but bouncing in and out you'd get a lot of noise.

Wobbling the tacho cable around shouldn't affect anything.

I'd set the tension as per the manual - then do what's not in the manual and lock it via the screw on the side and tighten the locknut too.
If this gets rid of the noise you've proved it's the tensioner.

FWIW, on GS's with the stock tensioner which are going to see the track or hard use, I lock the tensioner every time.

 

[Gorminrider]

If the tensioner isn't locking but bouncing in and out...

Yes, that's what it does in the video. Somebody might have taken it apart and reassembled wrong..?

 

[VGplay]

Next weekend... one month, what's the difference?

That was some really impressive detective work guys. Yes I did rebuild the tensioner using bwringer's guide. After reassembly the mechanism seemed to work as intended but the bike needed more work before I could ride enough to uncover this problem.

I'd set the tension as per the manual - then do what's not in the manual and lock it via the screw on the side and tighten the locknut too.
If this gets rid of the noise you've proved it's the tensioner.

FWIW, on GS's with the stock tensioner which are going to see the track or hard use, I lock the tensioner every time.

I removed the tensioner, reset it, and remounted it. I will admit when I first rebuilt it I did not do the step in the manual where you slightly turn the crank backwards before turning it correctly to set the tension. That certainly could've played a role. I also did as GregT recommends and tightened the lock screw after setting the tension.

And the chatter is gone! Took the bike around the block up to 55 and the engine is smooth. I think I'm a little lucky the chain didn't skip any teeth if it were flailing inside the engine, everything felt normal and in time.

What would the next step be? Just loosen the lock screw and see if it goes back to chattering? Is it advisable to ride the bike with the tensioner locked? In that case would I loosen the lock screw if I notice any change in cam noise? While I had the tensioner off I really worked it and didn't find any play that would explain the bouncing it was exhibiting, it let spring tension out and wouldn't push in without turning the knob.

I'm seriously impressed. Thank you all for your advice!

 

[free99]

Watching this thread, as I had an odd & similar issue with my tensioner until I kind of forced the knob clockwise.. Hadn't thought to lock it though.

GregT, when you do keep it locked, what are the constraints? I imagine you have to do that only after the engine is fully warmed up, as well as re-locked after every x miles?

 

[GregT]

Locking it via the screw on the side is effectively a poor man's manual tensioner.Same constraints as using a manual tensioner. Adjust when it gets noisy. Lock again after adjusting.I tend to adjust manual tensioners with the cam cover off. That way I can ensure it's not over-tensioned.You should be able to move the camchain sideways on the sprockets fairly easily once tensioned.If you can't, it's too tight.VGplay, unlock it and see what happens. If the bounce is back your tensioner needs a rebuild.

 

[VGplay]

I loosened the set screw and the chatter didn't return, I'll roll with it as is for now. Might be too soon to say the problem is eliminated but if it happens again at least I know the tensioner is the source. Might be a good idea to strap a 12mm wrench and screwdriver somewhere in case I need to lock the tensioner on the side of the road.

 

[VGplay]

Bah, had the chatter return last night. When I had the tensioner disassembled to replace the oil seal the spring and push rod were in fine shape, the problem must be in the knob assembly. That isn't listed as a separate part on the fiche so I guess a complete replacement is in order.

The complete tensioner is still available from part vendors. Any thoughts on staying stock or going with one of the manual tensioners off eBay?

 

[VGplay]

Hopefully this is the last update on the matter. I replaced the tensioner with a decent looking one from eBay. Immediately I could tell the knob had more spring tension than mine. I'm guessing I missed a turn of tension when replacing the oil seal, which didn't give the tensioner enough resistance to hold the cam chain in place.

I've ridden the bike almost 300 miles with the new tensioner and it seems to be holding. So hopefully it is all good to go now!

The replacement is on the bottom, compare the tightness in the springs.

Thank you everyone for your help with this. I wasn't thinking tensioner so I appreciate being pointed in that direction!

 

[Gorminrider]

First time a video has helped...You really don't need to ever lock the shaft unless you are removing the tensioner from the bike. They work ok as is and save the trouble of "adjusting cam chain tensioner" at tune ups that other bikes without it don't have. That said, there are those out there that consider setting tensioner manually is best and you CAN do that too. Turn the big knob slightly, release just til the bike is quiet, and lock it...that duplicates the way you would do a manual tensioner- tighten, then loosen a smidge and finally lock it. It's a chain on sprockets so just like all chains on sprockets, it needs a tiny bit of slack so the oil on the chain can get between the links and their shafts but never so much that the chain can flop about or ever get off the spockets...just like a bicycle chain, really.