Noisy Valvetrain 1978 GS550E

[enriquev9]

I’ve been resurrecting a 1978 GS550E. It is running but has developed a knocking noise that appears to be coming from the valvetrain. I can’t tell if it is pinging from a lean condition or the valve adjustment is off now that it started.

Here is what I’ve had to do to the motor because of rust that was in the engine.
1. Honed cylinders
2. installed new piston rings from Suzuki stock size.
3. Installed a used head that machine shop verified was good with vacuum test.
4. timed the cams and made sure the tensioner was installed correctly.

here are some important numbers:
compressions:
before noise developed:
cylinder 1 120
cyljnder 2 125
cylinder 3 120
cylinder 4 130

after noise developed:
cylinder 1 110
Cylinder 2 115
Cyljnder 3 115
Cylinder 4 125

Valve shims and valve clearances
cylinder 1
intake 2-75 (.04 mm clearance)
Exhaust 2.8 (.05 mm clearance

cylinder 2
intake 2-75 (.05 mm clearance)
exhaust 2.8 (.05 mm clearance)

cylinder 3
intake 2.8 (.03 mm clearance)
exhaust 2.9 (.05 mm clearance)

cylinder 4
intake 2.7 (.06 mm clearance)
exhaust 2.75 (.04 mm clearance)

im going to check the valve clearance again tomorrow but would like some guidance on if I set my clearances correctly and what I can do better.

also, when I first started the bike after assembling it, the valvetrain was making so much of a knocking noise. It has developed the noise recently.

any and all direction is appreciated.

 

[enriquev9]

Attaching a video.

I was also planning on re torquing the head bolts also.

 

[Rob S.]

1. Valve adjustment ??
2. Cam 'walk'??

 

[steve murdoch]

I am a little confused. The noise started after you adjusted the valves?
A long shot but it sounds a bit like an exhaust leak. Did all the exhaust gaskets get installed?

 

[Nessism]

You might want to check the cam chain tensioner to make sure it's functioning properly

 

[Cipher]

The compression change is likely the key. What could cause a 10 psi drop on 1 and 2 but only 5 psi on 3 and 4?
Recheck everything.
the only thing I think could change is timing jumped from an improperly operating tensioner or the head gasket was not properly torqued and it is leaking after heat cycling.

 

[enriquev9]

I am a little confused. The noise started after you adjusted the valves?
A long shot but it sounds a bit like an exhaust leak. Did all the exhaust gaskets get installed?

this project has been on the back burner for a while. Now I’m trying to finish it. I can safely say that when I moved to Arizona and was tinkering with the bike again it wasn’t making that sound. I started the bike one day after installing the tank and went for a test ride. (I really thought I was close to being finished). But then it started making that noise out of nowhere.

I can honestly say I adjusted the valves as I assembled the top end back together. Can’t remember how long ago that was.

I plan to take the valve cover off and hopefully I will get some answers.

yes. All exhaust gaskets were installed. I sprayed some WD40 on the exhaust and didn’t hear any change in idle or see bubbling.

Is there a better way to check for exhaust leaks?

 

[enriquev9]

You might want to check the cam chain tensioner to make sure it's functioning properly

I will need to check. Do I have to take the carbs off for this?

 

[enriquev9]

The compression change is likely the key. What could cause a 10 psi drop on 1 and 2 but only 5 psi on 3 and 4?
Recheck everything.
the only thing I think could change is timing jumped from an improperly operating tensioner or the head gasket was not properly torqued and it is leaking after heat cycling.

I agree on checking the tensioner. Will have an update when I take off the valve cover.

I also have a feeling that I need to re torque the cylinder head bolts. I just hope I didn’t blow the gasket

sorry guys. This has been quite an adventure for me with his bike.

 

[Guest]

"I’ve been resurrecting a 1978 GS550E. It is running but has developed a knocking noise that appears to be coming from the valvetrain.​"

I had that "knocking"/banging noise on a 2000 GS500E I had years back. I tried everything with no luck. It was bad at idle and faded as engine speed went up, completely gone @ +/- 2000 RPM. Bike ran great but embarrassing at stop lights. Even called Suzuki. Everyone said not to worry, no harm, was common issue. I gave bike away to a relative before I solved it. Not sure the "forget about it" advice was good. I would have kept chasing it but passed problem on with no guilt. Bike was stolen a few weeks after I gave it away. Nice bike but made me ride with less care than I do on my GS850G so better off without it. Good luck.

 

[enriquev9]

Update. I torqued the cylinder head to spec again. Some of the nuts were loose.

it’s fixed now. Way more quiet.

 

[chuck hahn]

To test the tensioner just gently turn the big knurled knob to the left a little. You should feel the drive rod pulsing. Also be sure it's adjusted right. Tighten the screw till it touches the drive rod then out 1/4 turn and tighten jam nut