Large Valve Clearances

[Dreef1999]

1977 gs550 Owned for 3 months. Previous history is unknown although it does run.

I pulled my valve cover off and measured my clearances and got some not so good numbers, spec is 0.03-0.08

4 of the valves had clearances between 0.076 and 0.102
#1 Intake
#2 Exhaust
#3 Exhaust
#4 Exhaust

2 of the valves were between 0.102 and 0.127
#1 Exahust
#3 Intake

#2 Intake was between 0.127 and 0.152
#4 intake was within spec between 0.063 and 0.076

I had some feedback in the shim club thread that unusually large clearances meant something might be wrong. I buried my head in the sand for a week but I feel like I can handle the bad news now.

So, here I am with 7 of 8 valve clearances over tolerance and not really a clue what to do about it. This could be bent valves? Could I have just pulled the newbie measuring job and everything is good and I am worried over nothing?

Somebody scold me or reassure me. I would put some pictures up but the camera is on a trip for a week.

 

[lurch12_2000]

1977 gs550 Owned for 3 months. Previous history is unknown although it does run.

I pulled my valve cover off and measured my clearances and got some not so good numbers, spec is 0.03-0.08

4 of the valves had clearances between 0.076 and 0.102
#1 Intake
#2 Exhaust
#3 Exhaust
#4 Exhaust

2 of the valves were between 0.102 and 0.127
#1 Exahust
#3 Intake

#2 Intake was between 0.127 and 0.152
#4 intake was within spec between 0.063 and 0.076

I had some feedback in the shim club thread that unusually large clearances meant something might be wrong. I buried my head in the sand for a week but I feel like I can handle the bad news now.

So, here I am with 7 of 8 valve clearances over tolerance and not really a clue what to do about it. This could be bent valves? Could I have just pulled the newbie measuring job and everything is good and I am worried over nothing?

Somebody scold me or reassure me. I would put some pictures up but the camera is on a trip for a week.

I wouldn't panic.
First, make sure you rotate the cams a few times more and measure them again with the lobes in the proper way the manual spells out..
Be sure you are using a metric gauge when measuring.
If the PO erred on bigger gaps then that might explain it. I don't think you have a problem yet as other than being noisier, their shouldn't be any damage.
You really only have one valve that is way over....the one between .127 - .152mm.

 

[bwringer]

Yes, please measure in mm. I'm having trouble understanding why you feel you have a problem.

You can get a metric gauge set that goes down to .04mm for about $5 at most auto parts stores, and it makes life a lot easier.

You can get a gauge set that goes down to .03mm for about $10 at most motorcycle shoppes. Look for the display of BikeMaster tools.

 

[Marine36]

You can order this set of feeler guages for 6.49 and they say they go as small as .02mm

http://www.sourcingmap.com/steel-metric-thickness-feeler-gage-gauge-002100mm-p-21339.html

 

[gane]

clearances

clearances

D, Bent valves usually exibit greater clearances than you show.before going nutz, try this. start & warm engine. then via squirt bottle spray water (just H20) into carb throats. in moderation. In the buiz we refer it to "steam cleaning". in some cases, the carbon build-up in cyl head /pistons end up on valve faces,giving excess clearance readings. ingested H2o often removes said bits. no paneca, but. usual wear is tightening of clearances, not vice versa. hope this helps. g

 

[Dreef1999]

0.076mm
0.102mm
0.127mm
I could buy a new metric set but I really don't see how that would help.

My concern is that lots of people suggest that the gaps normally shrink over time and for some reason most of mine are significantly over. Nessism came in and spooked me by mentioning "other" problems that this could be a symptom of.

Not a problem? Just buy my two new 2.95mm shims and get on with it? The Shim club doesn't even have them that big b/c nobody ever seems to need huge shims like that.

Mountain, molehill? PANIC!

 

[Steve]

... Be sure you are using a metric gauge when measuring. ...

Please be aware that this does not mean "use the metric equivalent on the 'inch' feelers".

"Inch" feelers are made to a specific size, which happens to be in fractions of an inch. (Duh.) Yes, they have a metric approximation printed on them, too, but it's just that, an approximation. The specs for our valves are given very simply in metric measurements, from 0.03 to 0.08mm. Happily, the shim sizes will take the clearance from one extreme to the other, so there is always a shim size that will work. Of course, you can always look for an "X" shim if you want to fine-tune, too.

.

 

[Nessism]

I use SAE feeler gauges and don't understand why so many people around here are against them. Just pay attention to what you are doing and there won't be any problems.

 

[Dreef1999]

Please be aware that this does not mean "use the metric equivalent on the 'inch' feelers".

"Inch" feelers are made to a specific size, which happens to be in fractions of an inch. (Duh.) Yes, they have a metric approximation printed on them, too, but it's just that, an approximation. The specs for our valves are given very simply in metric measurements, from 0.03 to 0.08mm. Happily, the shim sizes will take the clearance from one extreme to the other, so there is always a shim size that will work. Of course, you can always look for an "X" shim if you want to fine-tune, too.

.

I simply do not understand. The tools are adequate in this case but the carpenter might be lacking.

Why would 0.0015" not be close enough to 0.0381mm as to be useful?
Or why would 0.0025" not be close enough to 0.0635mm? inches x 25.4 gives mm which isn't an approximation. If you are arguing that the inch feeler is built to much less stringent tolerances then i might have my disagreements. Or is a metric feeler 0.03mm not actually 0.03mm and actually some metric mystery number?

In particular why shouldn't I trust these measurements if they measure out on the digital caliper enough to make me confident that my clearances are all unusually large?

Can we drop the suggestion to buy a magic metric feeler set and help me stress out about my motorcycle? I say this in jest because a measurement is just a measurement and the first thing I did was double check the thickness of the feelers in question. If there is something I could have done wrong that would have resulted in a consistent error then I am all ears but I am confident that as of my method now regardless of tool my clearances are large.

Should I be concerned about 7 of 8 of my tolerances all being over spec and should I do anything further to ensure a healthy and happy motorcycle? Or just buy my 2.95mm shims from Z1 and go on about my life?

 

[Nessism]

I'd install the shims you need, double check the clearance after the shims are in place, and then triple check after running a hundred miles or so. That is a very fat shim so it makes sense to me to watch the clearances to confirm everything is as it should be. Other than this, ride your bike and enjoy.

 

[almarconi]

Since most shims are available in .05mm increments why are you trying to measure the clearance to 4 significant figures

 

[Steve]

Why would 0.0015" not be close enough to 0.0381mm as to be useful?
Or why would 0.0025" not be close enough to 0.0635mm? inches x 25.4 gives mm which isn't an approximation. If you are arguing that the inch feeler is built to much less stringent tolerances then i might have my disagreements. Or is a metric feeler 0.03mm not actually 0.03mm and actually some metric mystery number?

OK, the 0.0015" will be VERY close to 0.0381mm. Probably exactly. No problem at all with accuracy, it's more of a convenience issue. Since the bike was designed with metric measurements, the specs are given in metric measurements and the shims come in metric measurements and increments, why not measure in metric. :-k

Now for rest of the story:
I have two sets of feeler gauges. BOTH of them are "inch" feelers.

One thing that makes the whole thing much easier is the spreadsheet that I have developed and have available for distribution. It will help you with the math and will help you keep track of clearances from one service interval to another. 233 members of this board have taken advantage of it and nobody has voiced any complaints about it to me. Send me an e-mail with a request and I will send you a copy, too.

.

 

[crapwacker]

I have two valves, both on cyl#2, that I can pass a .102(mm) feeler into. I got some 2.75 shims to replace the 2.70s that are in there, but they don't have the bevel, and the clearance was too tight. I don't recall how tight. I'm presuming they're from a different make? anyhow, I left it at .102mm. I hope it's not going to be detrimental. And yes, I'm using inch feelers. Vintage bike weekend is coming, and the awesome tool vender will be there. I'll metric up then!

 

[Dreef1999]

Since most shims are available in .05mm increments why are you trying to measure the clearance to 4 significant figures

Not a matter of desire just a factor of the tool. I have a standard(inch) set of feelers and the listed metric equivalent is down to that many sig figs. I am only really considering it relevant to the nearest hundredth.

Thank Nessism. I am going to order my shims and measure a couple of times. Then compression test and measure again in a couple hundred miles.

 

[Steve]

I got some 2.75 shims ..., but they don't have the bevel, ...

What bevel? :-k

I have seen hundreds of GS shims and have never noticed a bevel.

.

 

[crapwacker]

all my OEM shims have a minute bevel on both sides of them! Honest!

 

[Steve]

I guess I am going to have to get out the magifying glass and check my shims.

.

 

[salty_monk]

Yes, the OEM ones have a small bevel or chamfer on the edge all the way round, makes them much easier to remove.

With the Z1 ones which are flat I take a file & run a small chamfer around the edge both sides before fitting (or at least "break the corner" in toolmaking terms), this makes them a lot easier to work with.

I vote for using Nessism's method too - it's what I would do in any case. Either way if it doesn't work you'll have to crack the engine same as you would now if you really wanted to analyse what was going on in there....

Dan

 

[flyingace]

I understand your concern. If you are certain your measuring methodolgy is correct, then it isn't logical for those clearances to be that large. Usually they shrink slightly over the miles. I would suspect the PO of inserting too small of shims, but the shims you need to bring the clearances into spec are pretty darn big. Too big I think.

I will throw this idea out and maybe others can comment. Is it possible the bolts holding the camshaft bearings in place have loosened? This would effectively lift the entire cam up every time the valve was pushed in, bumping up the clearance.

 

[lurch12_2000]

I understand your concern. If you are certain your measuring methodolgy is correct, then it isn't logical for those clearances to be that large. Usually they shrink slightly over the miles. I would suspect the PO of inserting too small of shims, but the shims you need to bring the clearances into spec are pretty darn big. Too big I think.

I will throw this idea out and maybe others can comment. Is it possible the bolts holding the camshaft bearings in place have loosened? This would effectively lift the entire cam up every time the valve was pushed in, bumping up the clearance.

My point in an earlier thread, that the PO erred on gaps being too big. Unless you did the previous measurement, I wouldn't rely on what someone else did prior.

Good point. As a rule, I always check the 8 bolts one each cam (4 each side) to be sure they haven't loosened. I use the 2 finger setting (or you can use a torque wrench). You don't want to snap these bolts!!