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Valve ticking?

H

hannibal

Forum Mentor
I got my 77 GS750 back on the road after sitting for 18 months. Since then, I've done about 500 miles without problem. In the last few rides, I've begun to hear a foreign sound. To me, it sounds like a valve. I topped off the oil, and checked the cam caps and valve clearances, no improvement. I did a 50 mile round trip ride and the next day, the noise was even louder.

I started it up to take a vid. What does this sound like to you guys?

https://www.flickr.com/photos/151312078@N02/shares/7n30X3

In November 2016, a cam sprocket bolt backed out. This stopped the cam, broke the cam chain, and a piston hit a valve. I pulled the motor apart and fixed everything. Hadn't had any issues with the motor til this sound appeared. Help please!
 
My hearing stinks, so I skipped the video. Ok, 500 miles and then ticking shows up . Are you absolutely sure that the camchain tensioner was reinstalled correctly??
 
May be starter clutch bolts coming loose and ticking off the cases...and yes the sound can migrate and fool you from where its coming from.
 
You need a mechanic's stethoscope, or at the least a piece of wood or long screwdriver held to your ear to localise the noise.
 
Just to clarify, I rode several miles in more than a year after fixing the broken cam chain. Then I parked the bike for 1.5 years before riding again in December 2019.

The tensioner shouldn't be an issue, but I'll add it to the list of things to check

I'll look at the starter clutch. I've never had problems with it before which means it's due.

Thanks for the tip on a listening device. I'll rig something together.

Thanks again guys!
 
The noise sounds extreme to me. I don't know what the problem is but can't help but think it's cam chain related. I'd stop riding it until you figure out what's wrong. Checking the cam chain tensioner should be on your list and maybe see if you can notice anything wrong with the guides too.
 
Thank you Ed.

I took the tensioner off and reread the manual and bwringer's tutorial (http://www.bwringer.com/gs/camchaintens.html). I'm beginning to think I never set the tensioner correctly.

In the video, I turn the handle while pushing in the pushrod, then tighten the set screw (I took the lock nut off). Then you install the tensioner and undo the set screw 1/4 to 1/2 turns and the pushrod pops out. When I do this, the pushrod barely has any movement. But if I undo the set screw another 1 full turn, then the plunger pops out further and has far more movement. Is this how the tensioner should be working when it's installed?

https://www.flickr.com/photos/151312078@N02/shares/bx29x0
 
Yes
Now put the locknut on and tighten it up without turning the set screw
 
Sorry but no. Have a look at the shaft. I expect there's a flat spot on it where the set screw "rides". It's supposed to limit the extension. AND there's another reason-it ensures you put the thing back in so the wedge-shaped back end of the pushrod coincides with the wedge-shaped rod being pushed in by the BiG spring loaded knurled knob....this system ensures your tensioner is auto-adjusting. The shaft creeps out as the camchain wears, but does not go back in!

If you llock the shaft in the wrong position and then stick it back on the bike, loosen it wildly, I'm not sure what'll happen-it'd hopefully align itself as above, but...that's not what Suzuki would have you find out, I think.
 
Thanks guys.

Gormin, I'm trying to understand your comment. I'm quite sure I locked the pushrod in the correct position (all the way in). My question is how much movement the pushrod should have when the set screw os released.

In my original setup, the pushrod could only move a few millimeters. If I loosen the set screw further, the pushrod can move much more. To me, this means the tensioner can absorb more slack which seems like a good thing.

I honestly don't understand the function of the big spring loaded knob. To me, it serves no purpose other than to test that the tensioner is working correctly after it's installed.
 
The knob keeps tention on the drive rod. The rod floats and is continually adjusting when the engines running. Proper setup for the tensioner is to screw the bolt in till it touches the rod and then back it out 1/4 turn. Hold screw still with the screwdriver and tighten the jamming nut.
 
I’m wondering if you tore down the big spring knob part and didn’t put it back together properly. The tensioner will not work if that assembly is faulty.
 
I have two spare tensioners - unmolested- both behave similarly. Turn knob back ,push plunger rod back till it stops....now release knob, plunger rod will push out about 1/2 inch of travel.
 
Thanks to all for the replies.

I was confused about the range in which the tensioner operates. Fully compressed, the pushrod extends about 3.5cm into the motor. From the mounting surface, my chain guide is about 4cm inside the motor. So when the tensioner is installed and the set screw backed off 1/4 to 1/2 turn, the "big knob" is touching the bottom end of the pushrod and the pushrod would be able to provide tension on the chain as intended.

The good news is that my tensioner was assembled and installed correctly. The bad news is that means my problem lies elsewhere. My plan is to reinstall the tensioner, remove the valve cover, and spin the engine by hand and look for anything out of place.

Thanks again for the explanations about the tensioner.
 
You need to back off the lock screw enough to allow the plunger to move out fully and act freely. Don't think you can back it out too much other than if it falls out.
 
To me, it serves no purpose other than to test that the tensioner is working correctly after it's installed.
Click to expand...
It stops the pushrod moving back! It too is self-adjusting as cam chain wears. The cam-chain tensioner is a one-way device! and it doesn't bounce backnforth! Unless of course, you turn the big knurled knob with the engine running...because
if you want, you can turn the bigknob (a little! maybe Try turning the big knob next time you adjust valves to see what i mean) and the camchain tensioner will relax a little if the camchain is moving....some people even eschew the automatic function and effectively make it into a manual tensioner by setting the lockscrew when they "like the feel" of the camchain turning the knurled knob. Maybe it saves wear on the tensioner blade too? oh well.
Try turning the big knob next time you adjust valves...

Your cam chain only stretches when it wears. The pushrod only goes in against the blade to take up that wear. It's not much-the pushrod never will move much in the lifetime of a camchain.
 
Last edited:
Update!

Thanks for all the help. After removing the cams and inspecting everything I could think of, I didn't see anything wrong. I happened to pick up the intake cam by the sprocket and felt the cam wiggle. Just like three years ago, a sprocket screw had become loose. I'm just glad I recognized a foreign noise and stopped riding. This saved me from snapping the chain again and all the issues that followed.

I removed both screws on the intake cam sprocket, cleaned off the oil, and reassembled with Loctite blue (242). I put it all back together and the noise was gone. I've done about 50 miles since then and all seems well.

I used Loctite when I fixed this the first time, but I'm guessing I didn't clean the parts well enough for it to work as intended. I'll recheck valve clearances after a few hundred miles and double check the sprocket screws. Since my bike seems to hate these screws, I'll just check and tighten them every time I check valve clearances and hopefully I won't be this close to killing my motor again.

Thanks again for the help!
 
Just a quick note, from selling Loctite for 20+ years. Loctite hates any high temperature (long term temp resistance 150 deg C). It may work ok for a while but the temperature of the engine running may render the Loctite useless.
 
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