that idle ticking sound again

[vroomvroomvroom]

I took my valve cover off again and checked the cam end play, as others here have suggested causing the loud knock noise at idle.  I found the exhaust cam to make that exact noise when I slid it side to side!  My intake cam is not as loose.  I haven't measured the actual play yet (tomorrow).  I am guessing in the 0.030" range.  

Now it gets strange... I checked the parts catalogues on Bike Bandit and Ron Ayers Motorsports sites and found them to list thrust shims on both the intake and exhaust cams.  Mine do not have any.  I am planning on ordering some up.  Looks to be more than one per cam required (one variable thickness).  
The Clymer manual I have does not list a spec. for cam end play, nore does it show a picture of any thrust shims on the cam shafts.

to be continued,

[vroomvroomvroom]

I just got thru checking my cam shaft timing.  Here they are:

Intake cam lobe duration measured as 277 degrees and a 106-108 lobe center angle.

Exhaust cam lobe duration 267 degrees and 100-102 lobe center angle.

I checked as I was concerned about the cam timing after I shaved the cylinder head recently.  I am happy with these numbers for this engine.  I will not make any attempt to change timing.

[vroomvroomvroom]

I ordered the cam end play shims I mentioned above.  They are too thick to install on my cams.  I only have about 0.020" play in the loose cam (exhaust) and the thinnest shim available is like 0.040".  So, I am going to live with the noise, until I find a thinner shim to use.  I imagine end play should be about 0.010".  But, as I said, I am not sweating it now that I know what the noise is.  Rather harmless really.

[cernunos]

That's interesting on the cam timing specs. Most dual pattern cams tend to run more duration and lift on the exhaust side...our GS must have an efficient exhaust port...cool. Also, are those specs at .050" or .004" or what ...just wondering.

Cernunos

[The Buddha]

What... the cam shafts usually open the valve quicker than they close it, so the forward face of the cams are steeper than the back. Not heard of exhaust being different, of course valves are different sizes.
Cool.
Srinath.

[cernunos]

A dual pattern cam will have different duration and/or lift specs for the intake and exhaust. This will sometimes broaden the power band of the engine. It's done quite often with aftermarket camshafts and stock cylinder heads, especially where porting is not allowed. A lot of engines have more restrictive exhaust ports than intake ports so the exhaust side on these camshafts will have more duration and/or lift. For example, the lowly 318 chrysler LA engine will respond really well to a dual pattern camshaft vs a single pattern camshaft. Generally the increase is on the exhaust opening side because there are less pumping losses from opening the exhaust sooner anyway on fairly stock engines.

[vroomvroomvroom]

From what I have seen a lot of motorcycle cams will have less duration on the exhaust side.

The measurements were taken with 0.005" lift.

The lobe center angles were calculated from opening and closing points.

[70 Cam Guy]

It sounds like you know what you're doing so I'll toss out a possible solution although possibly costly.  A machine shop with a surface grinder may be able to take and grind that .040" shim down to .020" assuming its a magnetic grade of steel or if they have air chucks on their grinder.  I know it may be harmless but I also dislike having valve train noise on my transportation.  The only thing I hate more is exhaust leaks around headers.  Those can totally ruin the sound of a killer exhaust

[JLKasper]

Vroom,

I just found out that the cam shims weren't used on the '89 models. From '90 on, Suzuki milled .5 mm each from the camshaft thrust surface and off the inside of the cam bearing surfaces, then added a 1.0mm washer, with thicker washers available to eliminate noise due to manufacturing variations.  Unless you want to replace camshafts and heads just to get rid on the noise, you're stuck with it.  

[gitarman]

I too have an 89 and just started noticing the ticking from the cam-area. (My bike has about 19k on it). I took the cover off; the chain, bearings, cams looked fine as well. I tried giving it some 50 weight oil and about 3/4 quart of that along with the 40 weight that was already in it seemed to do the trick. This is the first oil change I've done since buying it from the previous owner so maybe they always used 50 weight oil. :dunno:

A side note: I know the auto cam tensioner has been faulty on these bikes, especially the earlier ones. Did the black engines have silver cam chain tensioner pistons or did the previous owner replace this?

[vroomvroomvroom]

If I recall, mine came with a silver CCT.  I junked that thing almost as soon as I got the bike.  It was shot at 10k miles.  I have installed an A.P.E. manual one.  

I seriously doubt that switching to 50wt. oil is going to do anything for my knock.  I currently use 20w/50 oil.  As I wrote above, I could slide the exhaust cam back and forth with the cam lobes off the tappets and hear a distinct knock sound.  

I am living with the sound, I am happy finding out what it was.  I was concerned there may be something going wrong with the balance shaft or elsewhere in the bottom end.  

When the CCT (cam chain tensioner) is bad you will hear a noise similar to the valves being very loose (slapping noises or rattles).  The cam end play noise is a distict knock (like a hammer hitting solid metal) that can be rather disturbing and only at idle.  The CCT noise can usually be heard at more than idle.

[vroomvroomvroom]

update:  I have recently performed another valve clearance adjustment, a few were looser than I had thought.  I also adjusted my APE manual cam chain tensioner again.  I have found the audible knock from the exhaust cam is much quiter now, but I can still hear it at idle in similar situations I have reported earlier.  I am pushing 46k miles now.

[The Buddha]

At 46 K mine was ~.5mm end play. The problem is ... 1 millimeter is the smallest shim there is. I had to weld up aluminum on the side of the cam cap and ground it to where it was under a 10th of an mm.
Cool.
Srinath.