GS1100 Skipping/Hiccup like water in the tank

[verboseone]

I have a 1982 Suzuki GS1100GL and I noticed that it has started to hiccup a bit at high rpms or on the freeway (basically it feels similar to when all the cylinders aren't firing and you need to switch to the reserve tank, less power and torque, but with hiccups). The engine will also sometimes die as I come to a stop (the RPMs drop below 1,000 and it stalls). It will start right back up.

The problem comes and goes. Sometimes it is bad enough I park the bike for a day. I have gone through 4 tanks of gas. So I doubt it is water in the tank.

I revved the engine up with the air box off and discovered the two middle cylinders butterfly diaphragms didn't rise at the same rate. I removed the carbs and sent them off to be cleaned.

All four spark plugs are grey and firing. (never been able to test when it is acting up). Compression on all four cylinders is over 130.

The gas I drained from the tank didn't appear to have any water in it.

Will the carbs likely fix my problem, or do I need to check other things??

EDIT: Just in case anyone is following this thread. This problem has been solved. The hiccuping was caused by the ignition system. The coils and ignition were replaced with dyna-s coils and ingition. It turns out the problem was not air/carb related at all.

[Adler]

Sounds to me like vapour lock in the tank. Make sure the little hole in the filler neck is clear. If it still happens after the carbs are cleaned, remove the tank cap when it happens and if the problem goes away, that's your problem.

[Nessism]

Have you adjusted the valves lately? Checked the charging system and the status of your battery? Petcock flowing properly?

[verboseone]

Valves were adjusted, petcock replaced last fall.
Battery and charging system tested around January. Replaced battery at that time.

[BassCliff]

Greetings and Salutations!!

Hi Mr. verboseone,

It's possible that your new petcock is failing. Did you buy a new OEM petcock or an aftermarket "oem-like" part? Have you checked the carb diaphragms for pinholes or tears? As has been mentioned, the gas cap has to vent properly and the hole in the filler neck in the fuel tank should be open. Are you using an inline fuel filter? Is the gas tank absolutely clean, no sediment? Is the float height properly set?

Anyway, let me dump a TON if information on you and share some GS lovin'.

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Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



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

[verboseone]

Sounds to me like vapour lock in the tank. Make sure the little hole in the filler neck is clear. If it still happens after the carbs are cleaned, remove the tank cap when it happens and if the problem goes away, that's your problem.

I'm not locating this hole. Its in the filler neck. Can you show me a picture?

[verboseone]

It's possible that your new petcock is failing. Did you buy a new OEM petcock or an aftermarket "oem-like" part?

I bought an after market petcock. I bought one from this guy on ebay, this looks identical to the one I bought.

Have you checked the carb diaphragms for pinholes or tears?

I checked one diaphragm and did not locate any holes or problems. (I checked the one that lifted the least when I revved up.)

As has been mentioned, the gas cap has to vent properly and the hole in the filler neck in the fuel tank should be open.

I can't find this hole. Where exactly is it located? How do I test the cap without waiting for the problem to come back.

Are you using an inline fuel filter?

I am not using an inline fuel filter because their is one on the petcock. (Should I be? My mechanic didn't think so.) Look at the link above to see my petcock.

Is the gas tank absolutely clean, no sediment?

I do not see any problems inside the tank. It looks really clean as far as I can tell. I currently have the petcock removed (from draining the tank). Is their something I should look at specifically?

Is the float height properly set?

What is the float height? Is this carb related?

[BassCliff]

Hi,

I'm not locating this hole. Its in the filler neck. Can you show me a picture?

It's under the gas cap in the filler neck, should be on the right side.



The gas cap itself is supposed to vent also. If you take the cap off and hear air rushing into the tank then the cap should be disassembled and cleaned.


Thank you for your indulgence,

BassCliff

[verboseone]

Thanks for the picture. I found my hole and it looks just as clean as the one above.

[BassCliff]

Hi,

Yes, float height is carb-related.







See the carb pages on my website for more information.

Thank you for your indulgence,

BassCliff

[verboseone]

I have sent my carbs off to be professionally cleaned and checked. I'm assuming the float height should come back correct. This is who I sent it too.

[BassCliff]

Hi,

I'm not sure what to tell you about that petcock. I don't believe that it's an OEM part. And I seem to recall that others have had issues, premature failures, with those style of petcocks. But test it thoroughly before you ashcan it. See if there is any gas leaking in the vacuum line (usually manifests itself with a fouled #2 plug). Make sure that it will not flow fuel in the "ON" or "RES" positions until you suck on the vacuum line. It should flow freely in the "PRI" position.

Has anyone mentioned a "carb balance" or "vacuum synchronization" for your carbs? Have you done that? I mention that because all of the slides should move more or less equally as you twist the throttle.


Thank you for your indulgence,

BassCliff

[fishfarm]

I have a 1982 Suzuki GS1100GL and I noticed that it has started to hiccup a bit at high rpms or on the freeway (basically it feels similar to when all the cylinders aren't firing and you need to switch to the reserve tank, less power and torque, but with hiccups). The engine will also sometimes die as I come to a stop (the RPMs drop below 1,000 and it stalls). It will start right back up.

The problem comes and goes. Sometimes it is bad enough I park the bike for a day. I have gone through 4 tanks of gas. So I doubt it is water in the tank.

I revved the engine up with the air box off and discovered the two middle cylinders butterfly diaphragms didn't rise at the same rate. I removed the carbs and sent them off to be cleaned.

All four spark plugs are grey and firing. (never been able to test when it is acting up). Compression on all four cylinders is over 130.

The gas I drained from the tank didn't appear to have any water in it.

Will the carbs likely fix my problem, or do I need to check other things??

Make sure the vacuum hose to the petcock is in good condition. I found mine was split at the carb.

[BassCliff]

Hi,

I have sent my carbs off to be professionally cleaned and checked. I'm assuming the float height should come back correct. This is who I sent it too.

I don't know that person and I don't know if he's a member here. There are members here that work on carbs, see the Services section. But let's assume that he does a good job cleaning the carbs, replacing all the O-rings, setting the float height, and bench syncing. Even after all that, the carbs must be installed on your bike in order to vacuum sync them and properly set the idle mixture screws. You'll find procedures on my website and by searching the forums.

When did your symptoms start? After the carb rebuild? If so, how soon after?


Thank you for your indulgence,

BassCliff

[verboseone]

The hose is in good shape. Before I sent the carbs off I cranked it without the tank on it. I could not feel a vacuum with my finger with it running. However, when I put the petcock back on .. I did get fuel. So I assume the vacuum doesn't have to be much, or am I wrong here.

I just took the gas cap apart. I see a ball valve that looks like it went vent just fine. So I think the gas cap is good. I did not see any gunk build up in the cap.

The fuel line from the petcock to the carbs was brand new and clear. I could see gas flow.

There was one time the bike acted up. I switched the petcock to prime, but the problem was still present. Maybe not as strong. But still there. Because the problem comes and goes I do not think switching to prime was what made my issue less noticeable.