Chattering cam noise is winding me up !!!

[Anonymous]

78 GS750. New cylinder head, new cams with only a few thousand (at most) miles on. VERY VERY good condition. Valves ground in, new oil seals, same springs also in good condition, well within spec. Carbs are balanced but the idle is slightly lumpy, it hunts a little. (I think it might be misfiring instead of 'hunting due to weak mixture', I am yet to investigate further).

Heres the crunch, there is a 'ticking' coming from the cams but I have double checked shims, and cam condition, cam covers (bearing caps) and cam chain. All appears sound. What the hell is it ? It doesn't go away with revs, although it doesn't get any worse, just a faster ticking.

Castrol GTX 10W40 just renewed.
Oil filter just renewed.

How quite are these engines normally ?

Are they naturaly quite noisy ?

Do the cams 'tick', kinda like a pushrod engine makes a ticking sound ?

If my carbs are off balance I get a big end 'clank', especially at idle. Its not that.

What does 'cam end float noise' sound like ? A 'ticking' or a 'clanking'.

This noise hasn't just appeared, its been there since I bought the bike 2 years ago. I have only done about 1000 miles on it.

Have I oncorrectly set valve clearances ? A 0.1 feeler doesn't fit, a 0.03 feeler does, the bucket turns freely. Surely that is within spec.

ALL help will be greatly appreciated.

 

[Anonymous]

The GS engines are noisy as hell! Fortunately it's mostly benign. The cam end float is a bit louder than a "tick", it's more of a clank i'd say. Just about every GS 4 cylinder i've ever been around makes a truck load of sound. Learn to love it. If it's making noise, it's running.


Tim

 

[Anonymous]

Sounds like an incorrect valve clearance. Valve clearance (cold engine) should stay between 0.025 and 0.055 mm for the intake valves (and should not exceed 0.09 mm) and between 0.04 and 0.07 mm exhaust (max 0.10 mm).

These clearances are for a GS850 and GS1000, but will do for a GS750 too.

Jojo

 

[TheNose]

My Suzuki service manual for 1981 GS750 and my Clymer manual for '77 through '82 GS750s both say to set the valve clearance to 0.09-0.13 mm (0.004-0.005 in) when cold.

Suzuki says:
Turn crankshaft to bring the "T" mark on Nos 1 and 4 side of the advance governor to the timing mark and also the notches on the right ends of the camshafts should be pointing away from each other. In this condition, read the valve clearance at the two leftmost valves at the front of the engine (left side while sitting on bike) and the leftmost valve on the back of the engine and the third valve from the left on the back of the engine. This in the Intake and Exhaust of cylindrer #1, Exhaust of #2 and Intake of #3.


Then rotate the crankshaft in the clockwise direction 360 degrees and realign the "T 1.4" mark. In this position, the notches on the right ends of the camshafts should be facing each other. Then check and adjust the valves that are the two rightmost toward the front and the second one from the left in the back of the engine and also the rightmost valve in the back of the engine.

CLARIFICATION:
First step do valves in positions marked X, then second step do valves in positions marked O.

(Front of Engine)
X X O O
X O X O
(Rear of Engine)

Hope this helps. If you need me to clarify this more, please let me know.

Terry

 

[Anonymous]

So there seem to be differences between GS850 and GS750 valve clearances. Good to know.

Jojo

 

[earlfor]

Re: Chattering cam noise is winding me up !!!

Sounds to me like you have a perfectly normal and healthy GS750.
My 79 750 has all kinds of clutch chirp sounds, valve train whirrs, rattles, and a varied asssortment of happy gurgles and chinks. heh heh It is basically a very talkative engine and I doubt you will ever come across one that is really quiet. In a way, that is a good thing because you learn to recognize the noises and you notice when one of them changes, so the bike tells you when something is wrong and even tells you what and where.

Earl

78 GS750..

Heres the crunch, there is a 'ticking' coming from the cams but I have double checked shims, and cam condition, cam covers (bearing caps) and cam chain. All appears sound. What the hell is it ? It doesn't go away with revs, although it doesn't get any worse, just a faster ticking.

 

[TheNose]

My apologies. I was wrong. The above instructions for valve adjustment are for an '81 GS750. I looked in my Clymer manual and it says the above instructions are for the TSCC models.

For '79 and earlier, to adjust the valves, rotate the crankshaft clockwise until one cam lobe is perpendicular to the cylinder head surface ( pointy end up) and check the clearance. It should be between 0.03-0.08 mm. (0.0012-0.0030 in) If necessary, adjust with a shim, if not rotate until the next lobe is perpendicular, and continue until all are checked.

Sorry for the confusion. I'm just learning this stuff too.

Terry

 

[Anonymous]

Here's a worst case scenario no-one else has mentioned, and I have personal experience of this. This depends on how loud this ticking is:
You have to be EXTREMELY careful with newly rebuilt GS engines (as yours appears to be) as it can take over 2 minutes for oil to get to the camshaft bearings from a fresh start. I didn't make this up, i've seen this myself and had it confirmed that it is correct by SEP who are among the best motorcycle engineers in the UK. The oil to the head on a GS is actually deliberately restricted by the reduced size of the oilways, so that oil flow to the crank is favoured.
Anyway, it is possible to have a cam bearing pick up when restarting these engines from a rebuild. This creates extra play which allows the valve clearance to grow when running, causing a fairly loud ticking noise. You can stand there with an oil can to get oil to the cam lobes, but its hard to get lube into the cam bearings. Moly grease and engine assembly paste are the answer.
I had to fit a new cam and have my head repaired when this happened to me.
Hope your noise is just normal, Hatter.

Remember, "Calm down, Calm Down"

 

[Anonymous]

All your answers were very much appreciated. The 2 minute delay in oil reaching the cams is interesting. Anyhow, I have managed to make the engine sound a bit more healthy. I removed the sump to take a look inside and check the oil strainer. "Completely clogged" is how I will describe it. Oil pressure must have been low with it in this state. So, cleaned it up good, cleaned out the sump also, it came up a treat. Engine has quietened down noticeably but it does chatter and clunk somewhat. Seems this is healthy after reading your replies. I'll keep my eye on it.

Do you guys ride off straight away or let the engine warm up and the oil circulate ?

I am slowly getting there with this thing ....

 

[earlfor]

The first time I start the bike each day, I let it warm up for about 4 or 5 minutes before taking off. After that, I just start it and ride off. I have checked my 750 after when I shut it down by pulling the valve cover to have a lookie see at the cam lobes. There is standing oil there, so I see no problem with riding off immediately during the day.

Earl

[quote="TheMadHatter"

Do you guys ride off straight away or let the engine warm up and the oil circulate ?

I am slowly getting there with this thing ....[/quote]