Feeler Gauge Wont Go Through Cam Lobes

[SB3]

I just recently put the head back on my 78 GS550 after cleaning the valves and installing new valve gaskets. As I proceeded to check the valve clearance I could not fit the thinnest part of my feeler garage (.0015 inch) through the clearance between my cam lobe and my shim bucket. I thought to loosen the cam chain and the cam caps but it still would not fit. Does anyone know what could have happened?

Thanks

 

[Nessism]

You need thinner shims.

 

[Guest]

I just recently put the head back on my 78 GS550 after cleaning the valves and installing new valve gaskets. As I proceeded to check the valve clearance I could not fit the thinnest part of my feeler garage (.0015 inch) through the clearance between my cam lobe and my shim bucket. I thought to loosen the cam chain and the cam caps but it still would not fit. Does anyone know what could have happened?

Thanks

What do you mean by valve gaskets? Valve seals? Did you remove the valves? Did you remove carbon build up in the combustion chamber, on the valve seats on the head and valves? Possibly mixed them up? Are all of them tight or are some of them really loose. Did you possibly mix up the shims?

 

[SB3]

What do you mean by valve gaskets? Valve seals? Did you remove the valves? Did you remove carbon build up in the combustion chamber, on the valve seats on the head and valves? Possibly mixed them up? Are all of them tight or are some of them really loose. Did you possibly mix up the shims?

yes, valve seals. Sorry got ahead of myself. Thanks for pointing that out! I removed carbon build up from my valves and the head of the combustion chamber. Also honed the cylinder walls. I labeled everything accordingly and even put everything in individual plastic bags so I highly doubt I got them mixed up.

Maybe the new valve seals are making the gap tighter???

 

[SB3]

You need thinner shims.

Thought that was the case, just didn't know if it was a bigger problem or not

 

[Nessism]

Maybe the new valve seals are making the gap tighter???

No.

Most likely the valves were carboned up because they weren't adjusted regularly and were hanging open (and losing compression), and now that you cleaned them they are seating down better onto the seat which moves them deeper into the head and thus thinner shims are needed.



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[Guest]

No.

Most likely the valves were carboned up because the valves weren't adjusted regularly and they were hanging open a little, and now that you cleaned them they are seating down better onto the seat which moves them deeper into the head and thus thinner shims are needed.

That's what i'm thinking if the parts didn't get moved around.

 

[Steve]

Depending on how you "cleaned the valves", you might have simply removed some carbon that was holding the valves open a bit or you might have removed a bit of metal. Either way, the valves are closing farther, which is now properly. As Nessism says, you need thinner shims.

May I suggest taking advantage of the offer in my signature?

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[SB3]

Depending on how you "cleaned the valves", you might have simply removed some carbon that was holding the valves open a bit or you might have removed a bit of metal. Either way, the valves are closing farther, which is now properly. As Nessism says, you need thinner shims.

May I suggest taking advantage of the offer in my signature?

.

I use a regular scotch brite pad and some WD-40. Attaching the valves to a drill. I was very careful to not remove any medal. Just as much carbon as I could without staying in one spot for a long time, maybe 10-15 seconds for each the bottom and tops of the valves. When I was done I dried them and sprayed for WD on them.

But yes, Steve, I sent you an email just now, I'd appreciate the spreadsheet I've read a lot about it!

 

[Nessism]

I use a regular scotch brite pad and some WD-40. Attaching the valves to a drill. I was very careful to not remove any medal. Just as much carbon as I could without staying in one spot for a long time, maybe 10-15 seconds for each the bottom and tops of the valves.

It seems pretty clear then that the motor was previously abused. For some reason a lot of people don't maintain their bikes; they ride them until they start to run crappy and then they try to figure out why. With shim type GS Suzuki's the valve clearance decreases with usage and eventually all the clearance goes away and the valves don't close anymore. When this happens the valves and seats accumulate carbon and compression goes down, and eventually the bike won't run well or at all. Suzuki calls for checking the valve clearance at 3500 mile intervals but it's startling how many owners don't pay attention.

 

[SB3]

It seems pretty clear then that the motor was previously abused. For some reason a lot of people don't maintain their bikes; they ride them until they start to run crappy and then they try to figure out why. With shim type GS Suzuki's the valve clearance decreases with usage and eventually all the clearance goes away and the valves don't close anymore. When this happens the valves and seats accumulate carbon and compression goes down, and eventually the bike won't run well or at all. Suzuki calls for checking the valve clearance at 3500 mile intervals but it's startling how many owners don't pay attention.

You hit the nail on the head, I bought the bike off a guy that I'm pretty sure was a drug head... So he probably didn't take care of it all

 

[hannibal]

Does you guys recommend running the motor before replacing the shims?

For example, if the OP goes down one size on the shims now, is it likely he'll need to go down another size after running the motor?

Another example: my bike has sat for a year. Should I ride it for a few days/miles before I check and replace the shims or can I check shims now?

 

[Steve]

Not sure if running it first will help any, but you do need to make sure the engine has not been run for at least eight hours before checking clearance. Since you are at that "8 plus" right now, why not do it?

.

 

[Nessism]

I've done valve checks after less than 1 hour cool down using a fan blowing on the engine. As long as you can put your hand on the cams and don't feel an increase in temperature you are good to go.

Regarding running the engine after a rebuild before checking the valves: NO! Do them before running the engine and then again after a few hundred miles.

 

[Steve]

Ed, have you ever compared clearance on hot and cold engines? I am curious how much it changes, but have never been quite curious enough to take the time to do it myself.

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[robertbarr]

Before you get rolling, I'd pull the shims (one at a time, of course) and measure them. Write down the measurements. It helps to be able to swap a shim from one valve to another as needed, but you'll also find your thinnest shim, which might -- MIGHT -- be thin enough to make measurements. Probably you'll wind up procuring shims twice, but that's not the end of the world.

Keep track of the thickness of the shim you end up with for each valve. Since the valves were disturbed, it's probable that your clearances will change in your next 3,500 miles, and having that shim 'map' will come in really handy next time around. (Imagine how handy it'd be right how, for example...).

 

[Nessism]

Ed, have you ever compared clearance on hot and cold engines? I am curious how much it changes, but have never been quite curious enough to take the time to do it myself.

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I've never done a hot check Steve. Too lazy. The reason for doing the fan cool down is because I help a local member do maintenance on his 850 and we usually drink a beer (or two) while draining the oil and cooling the engine with a fan before we dig into the valves. Most of the time the valves are okay or maybe just one or two need a shim.

 

[Steve]

I've never done a hot check Steve. Too lazy.

You sound about as ambitious as me.

Thanks for the reply. :encouragement:

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[sharpy]

"Feeler Gauge Wont Go Through Cam Lobes" Almost none will. but most of the time they go under the lobes between the shims and lobes

 

[hannibal]

Thanks guys.