Upper engine clatter

[egleaves]

Hello all, I just acquired a 1980 GS550E and this looks like this is the place to consult the gurus.

Here's what's up....about 50 miles into my ownership of this bike a "clatter" began emitting from the engine. Sound like the valve train. A load on the engine would silence the noise, either by accelerating or decelerating, it's as though tension or pressure is being applied on accel and removed on decel.

Edit: I don't know why this posted before I finished writing. Something up with my tablet.

Anyway, the noise is amplified by the gas tank and it sounds like there is an angry woodpecker in there. I got the valve cover off, but nothing is obvious yet. My search of the forum suggests either valve shims or cam chain tensioner are the problem. Anyone ever experience a noise that comes and goes with engine load? Have to go now, will update with any new info. Thanks in advance.

[hannibal]

I would guess an issue with the cam chain but I'm far from a guru.

[gearhead13]

How many miles? has the valve lash ever been checked?
Sounds like cam chain noise to me, take the tensioner off and check its function.

[fastbysuzuki]

Does sound like it could be cam chain slap if it is it could be the tentioner not working correctly download the service manual Here and study the sections on the tentioner one is how to strip and check it and the other how to install it I recommend you read and study it a couple of times as some people get it wrong.
Also I would be checking the valve clearances who knows when they were last done and while you are there you could check the cam chain for wear as in the manual.

[tom203]

Read thiis about cam chain tensioner.. note stuff by bwringer . Tensioners often get installed wrong and work briefly before disaster strikes!

http://members.dslextreme.com/users/storagecliff/images/engine_odds-n-ends.html#A05

[egleaves]

I'm going to check the valve clearances tonight if I can find my feeler gauges. It's got about 40K on the clock and I have no idea when clearances were last checked, but judging by the condition of the bolts and the gasket I don't think the valve cover has been off anytime recently.

[chuck hahn]

Check the chain tensioner too as was mentioned above.

[chuck hahn]

Scroll down here and read the tensioner information

http://members.dslextreme.com/users/storagecliff/images/engine_odds-n-ends.html

[egleaves]

Thanks all....that gives me some good reading and a direction to focus.

[chuck hahn]

Store this place and get aquainted with it. Lots of turorials on each margin and a good service manual menu also.

http://members.dslextreme.com/users/storagecliff/images/engine_odds-n-ends.html

[chuck hahn]

Do the tensioner first..it may eliminate the needs to even take the cam cover off. Unless you just want to do the valve adjustment and get a new cover gasket that is. If the rattle goes away with the tensioner check, then ride the bike a week or so till the new cover gasket arrives and THEN crack it open.

Note that in the services forums we have a shim club. check that out too before buying shims.

[egleaves]

So, last night I went through this procedure as recommended:

Loosen the lock nut on the left side of the tensioner and back the slotted bolt out 1/4 turn. Turn the knob on the right side of the tensioner, which in the Suzuki service manual is called a lock shaft handle, counterclock-wise. As you are turning the knob counterclock-wise push the pushrod all the way back. Keep turning the knob until it refuses to turn any further.

With the pushrod still pushed in as far as it will go tighten the slotted bolt so that the pushrod will not plunge out.

Remount the tensioner to the cylinder block. If the tensioner is not going in turn the crankshaft clockwise slowly to get slack in the cam chain on the intake side of the block.

Loosen the slotted bolt 1/4 turn allowing the pushrod to advance towards the cam chain. Tighten the lock nut but leave the slotted bolt loose by that 1/4 turn.

While turning the knob counterclock-wise, slowly rotate the crankshaft in reverse direction, counterclock-wise. This causes the chain to push the pushrod back.

Release the knob and slowly turn the crankshaft in the normal direction, clockwise. You should see the knob rotate as the chain becomes progressively tighter. If it does the pushrod is obviously moving forward under spring pressure signifying the tensioner is in good operable condition. If it moves sluggishly or not at all that means the pushrod or the slotted bolt is sticking. If so remove the tensioner from the block again and inspect the pushrod. It could need cleaning or could be bent or galled. Further crank rotation will take the slack out of the cam chain.

After releasing the knob and turning the crank forward, the knob did not rotate on its own. I then loosened the locknut on the left side and backed off the screw 1/4 turn. (It may be noteworthy to mention that my screw is not "slotted" as i have read about others, it is an allen head machine bolt. Aftermarket part? Different year? Shade tree engineering?) Anyway, backing the screw out and re-locking the nut resulted in the procedure above working as described. What I think I did was reset the tensioner. Am I close to correct on that?

While I was in there I wanted to check valve clearances, but my feeler gauges only go down to 0.004in, and the spec is 0.001-0.003in. The good news is that I couldn't get the 0.004 gauge into any of the gaps, so that tells me that they are not so wildly out of spec that I have a shim dancing around in the bucket.

I'm optimistic about the chain tensioner adjustment, but I welcome any opinions there. I can't run the bike to check for the noise until I get my hands on a new valve cover gasket.

[fastbysuzuki]

personally like a lot of others on here I would set the valve clearance to ."004" this will do no harm been running that clearance for 30 years. the problem is if there in not enough clearance, when the cam is in the correct position can you turn the keepers if so you have clearance ( correct or not) what you must not do is remove a shim and turn over the engine. personally I will only use Suzuki shims not copy's I am in the UK so I do not have the luxury of the shim club which is very good.

[chuck hahn]

Spend 10 bucks and get a combination set of SAE and Metric feelers. Also remember this:: if the shim bucket will rotate with a little finger pressure or a small screw driver in the notch in the bucket you at least do have "some" clearance. What you do not want ever is a shim bucket that will NOT rotate.

Proper setting of the tensioner is to turn the screw in just till it stops and then back out the 1/4 turn and lock the jam nut with the adjuster screw at the 1/4 out.

[egleaves]

The source of my noise is the petcock! This thread perfectly describes my issue:

http://www.thegsresources.com/_forum/showthread.php?247591-1980-gs550e-fuel-tap-tank-noise&highlight=Petcock+noise

When I put a vacuum gauge on it I can watch the needle bounce in time with the noise. This explains why the noise would stop with the engine under load...there is enough vacuum to hold the petcock open. At idle, though, the vacuum is erratic and the petcock is rapidly opening and closing.

So, new questions. Shouldn't the vacuum be pretty stable even at idle? The line from the carb to the petcock is the entire vacuum system, right?