Valve shims on a 82 gs550mz

[zacheriaj]

i checked my valve clearences today on my gs and noticed that not even the smallest feeler guage will fit between the lobes and shims. does this mean i need new smaller shims? can i just shave them down by sanding the bottoms of the shims down a hair at a time very carefully? Or would anyone on here be willing to trade my shims for a thinner set? I notice that the bike will only run on quarter choke and when you hit the throttle, it doesnt do anything but bog down and flood. is this caused by the valve adjustments? also, it backfires really bad out of the exhaust if you have it on more than quarter choke and try to start it. Thank you so much for your help!

[almarconi]

i checked my valve clearences today on my gs and noticed that not even the smallest feeler guage will fit between the lobes and shims.

Did you have the cams positioned properly when taking your measurements?

can i just shave them down by sanding the bottoms of the shims down a hair at a time very carefully?

You could probably turn them down using a lathe, I doubt you could get them uniform enough with sandpaper.

I notice that the bike will only run on quarter choke and when you hit the throttle, it doesnt do anything but bog down and flood. is this caused by the valve adjustments?

Misadjusted valves will usually make the bike hard to start..what your describing is probably a carb problem. When was the last time you really cleaned your carbs?

I would adjust the valves before trying to adjust the carbs. Clean your carbs and while they are soaking, adjust the valves.

You should be able to get shims at your dealer or swap with some users on here. I think there is a shim club where member swap shims. I really haven't paid much attention because my bike has tappets, I don't need to mess with shims.

[zacheriaj]

i did in fact have the lobes positioned correctly. I will try to shave them down and see what happens. The carbs sat empty for about a year before i tried to get the bike running so should i just take the rack off and dipp them in cleaner? for how long? how exactley do i take them off? thanks!

[Griffin]

Shaving them down is a bad idea. You will not be able to get them uniform, they are very hard steel anyway, and you will accomplish little other than ruining some good shims. If they are so tight that with the cams in the proper position there is no clearance, buy a 2.20 shim and use it as a "feeler" shim for each valve to determine what size shims you need.

At least, that is the proper way to do it.

[zacheriaj]

If they are so tight that with the cams in the proper position there is no clearance, buy a 2.20 shim and use it as a "feeler" shim for each valve to determine what size shims you need.

At least, that is the proper way to do it.

What exactley do you mean "Feeler Shim?" im brand new to this shim adjustment type engines so im not completely comfortable with all the terms yet forgive me hehe. (used to the nice old tappet type valves)

[Steve]

Let's say, for instance, that you have 2.70 shims and can not use your thinnest feeler gauge. Do you need a 2.65? Or maybe a 2.60? If the valves are in really bad shape, maybe a 2.55? You really don't know until you change and measure. The best way to prevent buying unnecessary shims is to buy one shim that is considerably smaller than any that are in your engine now. Griffin suggested a 2.20 shim. Put in that 2.20 and measure your clearance. If you now measure .32mm, know that shims go up in .05 incrrements, so you will need one that is .3 larger than the 2.20, so order a 2.50. That is how a 'feeler shim' works.

.

[BassCliff]

Greetings and Salutations!!

Hi Mr. zacheriaj,

It sounds like you are trying to learn a great deal in a short amount of time. I applaud your efforts. I'll do my best to get you off on the right foot. In the "mega-welcome" below, pay close attention to the "Top 10 Common Issues" and the Carb Rebuild Series. Let me roll out the welcome mat for you and get you started on your GS adventure.

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[ptm]

How thick is your 'smallest' feeler gauge? The valve clearance is 0.03 - 0.08 mm (0.001 - 0.003") which is really small - smaller than most feeler gauges. Before you replace any shims you should get a feeler gauge that goes down to at least 0.08 mm, preferably 0.03 mm. That's the best way to measure.

If you can't find a proper feeler gauge, you can get a very thin shim and use it as described above. It's a little more work, but at least you're making decisions and replacing shims based on a measurement, not a guess.

If the bike is running poorly, properly adjusting the valves is the first step before making adjustments to the carbs or ignition.

Follow BassCliff's links, read the manual, search the forum, ask questions and be patient and you'll get it running better sooner.

Good luck.

[Commodus]

Did you have the cams positioned properly when taking your measurements?



You could probably turn them down using a lathe, I doubt you could get them uniform enough with sandpaper.



Misadjusted valves will usually make the bike hard to start..what your describing is probably a carb problem. When was the last time you really cleaned your carbs?

I would adjust the valves before trying to adjust the carbs. Clean your carbs and while they are soaking, adjust the valves.

You should be able to get shims at your dealer or swap with some users on here. I think there is a shim club where member swap shims. I really haven't paid much attention because my bike has tappets, I don't need to mess with shims.

I don't think turning them on a lathe will work. They won't be perfectly flat, no matter how good the setup on the lathe.

You could have them ground down using a surface grinder. They are hard steel, but are they hard all the way through? I guess you could destroy one to find out, you'd have to know before considering changing their size.

[DimitriT]

I recommend you first use a valve depressor tools or a zip tie to remove each shim which is
too tight and write down its size. The size is printed or struck on the reverse. Make sure
you put the shim back with the size facing away from the cam lobe.

Once you have all the sizes written down then you can figure out what new sizes you will
need. In some cases you can swap shims to get the right clearance. You will need to buy
at least one shim so you can do the swap. You don't want the lobe resting directly on a
tappet.

When replacing a tight shim try going with a thinner shim in .05mm increments. Shims also
come marked with an x which is "in-between" sizes. So if the shim is marked 2.65x it means
that the size is between 2.65 and 2.70 mm.

In general you want to get them between .03 and .08 mm of clearance but if you can't its
better to be a little loose than a little tight.

[Steve]

You could have them ground down using a surface grinder. They are hard steel, but are they hard all the way through? I guess you could destroy one to find out, you'd have to know before considering changing their size.

There is a 'shim club' on this site, and the manager of that club has had access to such a grinder and has reported a modest success in grinding down some shims. Because I am a bit leary of the hardness issues that you mentioned, I have not indulged in 'the club'.

Once you have all the sizes written down then you can figure out what new sizes you will need. In some cases you can swap shims to get the right clearance.

One more tool for your arsenal: send me an e-mail request, I will send you a copy of my Excel spreadsheet that does exactly what Dimitri mentions. Just enter your measured clearances, enter your shim sizes, it will tell you what shims you need. Compare that with what's already in there and you can see what you can move around and what you will need to buy. Finally, enter the shim sizes that you left in there, along with final clearances and you will have a record for reference the next time you adjust the valves.

.

[Ghostgs1]

The process I've used is a polishing process, not a machining one, using a Lapmaster and 1500 grit aluminum oxide abrasive. It works very well and does not have any effect on hardness. It does not generate appreciable heat so it does not affect the heat treatment of the shim. Ray

There is a 'shim club' on this site, and the manager of that club has had access to such a grinder and has reported a modest success in grinding down some shims. Because I am a bit leary of the hardness issues that you mentioned, I have not indulged in 'the club'.



One more tool for your arsenal: send me an e-mail request, I will send you a copy of my Excel spreadsheet that does exactly what Dimitri mentions. Just enter your measured clearances, enter your shim sizes, it will tell you what shims you need. Compare that with what's already in there and you can see what you can move around and what you will need to buy. Finally, enter the shim sizes that you left in there, along with final clearances and you will have a record for reference the next time you adjust the valves.

.

[Commodus]

The process I've used is a polishing process, not a machining one, using a Lapmaster and 1500 grit aluminum oxide abrasive. It works very well and does not have any effect on hardness. It does not generate appreciable heat so it does not affect the heat treatment of the shim. Ray

Neither will surface grinding if done properly, and heat treatment is not the issue.

Regardless whether lapping or grinding is being used, the nitriding case-hardening process (I'm just assuming here that this is what's being used) can certainly be less than .005 (on each side, of course), which is not out of the theoretical range of alteration required.

Of course if you've done it and it works, the point is moot. Maybe the parts really are just hardened all the way through. Seems unlikely to me, but it's possible.

[Gumbo76]

How do you know???

So many experts here... how do you know if you need to adjust your shims? What wears in order to make a valve adjustment neccessary? Forgive me for being a bit behind here, but I am thinking I may need an adjustment. I hear a bit of ticking in my engine. Not much. I've read some things on this forum that say it is normal. Just part of the GS family. I am also getting slightly less-than-average gas mileage too. Could that have something to do with teh shims? My Carbs have been cleaned and adjusted, but may need a bit more fine tuning. not sure though. It seems to drive nicely.

Any thoughts? Any answers?

-Gumbo

[Griffin]

So many experts here... how do you know if you need to adjust your shims? What wears in order to make a valve adjustment neccessary? Forgive me for being a bit behind here, but I am thinking I may need an adjustment. I hear a bit of ticking in my engine. Not much. I've read some things on this forum that say it is normal. Just part of the GS family. I am also getting slightly less-than-average gas mileage too. Could that have something to do with teh shims? My Carbs have been cleaned and adjusted, but may need a bit more fine tuning. not sure though. It seems to drive nicely.

Any thoughts? Any answers?

-Gumbo

Whenever pick up a "new" bike, one of the first things on the list of required things to do is check valve clearances. Ticking is normal, the looser the clearances, generally the more ticking you hear. They tend to tighten over time.

Probably the most obvious issue associated with too little valve clearance is hard cold starting. Lack of power is also an indicator.

You should really check valve clearances and adjust as necessary. If you do have to adjust them, you'll have to resync your carbs.