GS1000G valves cleareances down to a bare .02

[Lorenzo]

After the umpteenth leaking valves cover gasket, and waiting for the oficial Suzuki dealer to reopen, I tougth what better time than this, to check the clearances and eventually order the relevant shims, before installing the new gasket.
Well, to my surprise, none of the gaps was bigger than .05 (the thinner gauge I had).
I did turn the camshafts, a complete revolution rto double check, just in case.
Ever happend to anyone?
What could be the cause?
I only had, since the last time I checked them, an MOT visit, for which I had to lean the mixture, least I do not pass it.
This are the plugs.


And this are the values before a leaned the carbies
Of course at the time I did bot have a feeler blade smaller than .05 but you can see, there are values bigger than that (>0,05) --of course .05=0,05--



Thanks

 

[Big T]

Okay, what method did you use to measure?
This one?
http://members.dslextreme.com/users/bikecliff/images/gs850valve_adjust.pdf

If you didn't follow this method, the measurements will be incorrect
Plus, you are talking in millimeters and not inches?

You measurement should be .03 to .08 mm
If your measurements are less than that, time to replace the shims
Go to Steve's page and request a valve adjust spread sheet
Since you know your current shims sizes, you should be able to get the correct sizes
You can us the Shim Club if you need smaller shims
Whatever you do, do not turn the motor over with a shim removed!!!!

 

[Lorenzo]

I indeed followed the basscliff method.

In metric we put a comma plus a zero in front of the fraction of a number; in the imperial standard you put a period before the fraction and make the zero in front, redundant;
so basically .05 = 0,05 and yes, we are dealing with mm.

Of course I am looking at a full swap of the shims, but I do not reckon this kind of gap erosion, should develop in a three months time span.
Is there something wrong with the engine? I feel a lile worrysome, in a way that, if the trend should go on at this pace, the head will soon run out of useful material(?)...

Does green gas take part in the valve seats, depleting reaction, in spite of the blurb saying this engines are "happy" with it...??

Thanks

 

[bwringer]

One thing that's happened to me more than once is that two feeler gauge leaves are stuck together.

Also, the smallest feeler gauge I've ever seen is only 0.03mm -- this is incredibly thin and fragile, and is nearly impossible to use without damaging it.

A .02mm gauge would be completely impossible to use. If that .02mm gauge is any stronger than a soap bubble, then it's either stuck to another gauge or the decimal point or units are wrong.

In any case, as you know, you do not really need a .02mm gauge or even a .03mm gauge -- you can do a valve check with a .04mm gauge (very few sets include a .03mm gauge, but many include .04mm).

If your .04 will not go in, does it hit a hard stop, or can you push harder and get it to go in? You can also try to spin the valve buckets -- this will help you figure out whether the clearances are less than zero

I don't know the history of your bike, but a sudden decrease in valve clearances may just be carbon. When you put an older engine back on the road, there are sometimes carbon deposits that hold the valves open a bit. After the engine runs a while, these deposits are worn away and the clearances are suddenly a lot less. Once you set the clearances correctly they're very stable.

I'm not sure what you mean by "green gas", but unleaded gas and gas containing up to 10% ethanol does not affect GS valves.

 

[Lorenzo]

Also, the smallest feeler gauge I've ever seen is only 0.03mm

I know, they are hard to come by, I found it in a stall selling ex Warsav Pact stuff;

Three months ago, I did it with my 0,05 (.05) gauge and, as you can see, from the jotted data, in some buckets it went through, in others got stuck, but the fact was, some valves had at least .05 of gap; now not even two cents.

Yes the gauge, is very thin, and I cheked it with an lcd vernier caliper, and it reads .02 (0,02)mm

there are sometimes carbon deposits

I hope so, anyway, this engine is going to be on the bench, this winter, too many leaks, not even a bonnie... so I will look through the valves seats condition(also).

In the mean time, I'm gonna order a set of shims.

Thanks

 

[jeff.saunders]

If you can turn the shim and bucket, you know you have clearance. You can assume it is between your thinnest feeler gauge and zero. Reduce the shim thickness by one size to get back into the correct range.

If you recently rebuilt the cylinder head, the valves can settle in a small amount. Usually I set my valve clearances a little wide if I had valves recut or lapped in. Then after a few miles I check the clearances again.

 

[Lorenzo]

​Jeff, the problem is I did put #4 exh 2,60 shim to #1 (which had a 2,70) but still had no clearance...

No I did not rebuild the head. but I can envisage. as some fellow said. that I might have shed some carbon deposit, through the combination of a leaner engine, 500km+ stints and an exceptionally hot summer (the engine never felt so cold since I had it).

One day, the right hand throttle, was so hot I thought the electricc wires where melting down, bu it was only the heat from the engine with the bike leaned on the side stand, in the ten seconds it took me to open the garage door.
Thanks