Hey everyone! I'm new to this forum, as well as being a relatively new rider (a little over a year) and I have a question about a problem I'm having with my '92 GS 500E.

For some reason the right side sparkplug gets fouled with black sooty carbon every time I ride her. Of course the performance gets steadily worse until I have to pull the plug & scrub it with a wire brush, and even that only works so many times before I need to get a new plug. Other than that, she seems to work fine.

A friend of mine suggested that the carbs may have some oil sludge in them and need to be replaced or cleaned out, or maybe rebuilt. Others have said that the fuel mixture is too rich and the air/fuel screw needs to be adjusted, some just say I need a newer bike. Unfortunately I'm a poor man (the bike is my transportation 'cause I can't afford a car), but I do have a friend with tools and mechanical know-how (the one who suggested changing the carbs).

Any suggestions as to what I can do to get her running reliably?   

the air/fiel mixture is definitely too rich. As for the reasons, there can be few. If it was me, I would probably start by cleaning the carbs. Take them all apart and clean everithing.
After the cleaning, they need to be set up properly. That involves setting floats, idle air/fuel mixture, synchronizing the carbs and setting the idle revs. While having the carbs aprat, make sure that the jets are of the same size between left and right carbs. Maybe the previous owner screwed that up and installed different size jets for some reason.

Also check the condition of the air filter.
If it is cloged up, the mixture will be too rich as well.

Jenya

Will do. Thanks Jenya.

another member is experiencing similar issues and as Kerry made notice of,  it is quite likely you have an electrical issue with that cylinder

im going to have to give jenya a *bump* on this one.   CLean the carbs out.  Once this is done if you still have issues then you can try to check on the electrical ghosts that may be haunting the bike.

Quote from: spcterry on January 06, 2008, 01:32:13 PManother member is experiencing similar issues and as Kerry made notice of,  it is quite likely you have an electrical issue with that cylinder

I'm gonna go more with Jenya on this one too.  The other person I'm trying to help says the bike runs terribly.  I suspect an electrical issue, which would indirectly result in unburned fuel and therefore a carbon-fouled plug.

But cerebus hasn't said that the bike runs terribly; just that the one plug eventually gets carbon-fouled.  So I'd start with the symptoms mentioned for the Carbon Fouled entry on the [Haynes Spark Plug Chart].

A blocked air filter would likely affect both cylinders, unless you've got separate filters for each carb.

I suppose it's possible to have a fault in the choke (plunger problem?) for one carb and not the other.  Hmmmm....

Jenya's "oversized jet on one side" idea is certainly worth investigating.

Bottom line: If you don't know the state of the carbs on your used bike, and you're comfortable with digging into them, it would be good to document a known baseline (carbs are CLEAN, jet sizes are __ and __)  before looking further, like nastytnate6695 said.

Quote from: Kerry on January 07, 2008, 12:09:46 AM

I'm gonna go more with Jenya on this one too.  The other person I'm trying to help says the bike runs terribly.  I suspect an electrical issue, which would indirectly result in unburned fuel and therefore a carbon-fouled plug.

But cerebus hasn't said that the bike runs terribly; just that the one plug eventually gets carbon-fouled.  So I'd start with the symptoms mentioned for the Carbon Fouled entry on the [Haynes Spark Plug Chart].

A blocked air filter would likely affect both cylinders, unless you've got separate filters for each carb.

I suppose it's possible to have a fault in the choke (plunger problem?) for one carb and not the other.  Hmmmm....

Jenya's "oversized jet on one side" idea is certainly worth investigating.

Bottom line: If you don't know the state of the carbs on your used bike, and you're comfortable with digging into them, it would be good to document a known baseline (carbs are CLEAN, jet sizes are __ and __)  before looking further, like nastytnate6695 said.

So it has been said....So let it be written..   

When one of the gs gods speaks thats usually what is wrong with the bike

Many thanks for all the info. This is great help. 

I would say that given the description, the problem is fuel-based.  If it were electrical, it would never run great and certain times it would run fine, and others it would run terribly.

I personally have had ALLOT of experience with plug fouling (seems like every engine or vehicle I've owned had it for one reason or another).

Since it's one carburetor, things are a little more simple to diagnose.  I would take both carbs off the engine.  Before you do that, make sure both choke plungers are going in as far as possible and that the linkage is closing and opening both chokes by the same amount.

If that looks fine and good, take the carbs off the bike and get to disassembly.  If all the jets look clean (light can be seen through the hole(s) of the jets, those are fine.

Next you should check to make sure the jets haven't been reamed out by improper cleaning.  I use metal jet cleaners and GENTLY insert each pin until you find one that fits inside the jet hole with little to no slop.  After you find the size, use a micrometer and document the size.  Typically, people will try to ram the largest jet cleaner possible into the jet, which actually makes the hole bigger and makes the engine run richer than it should.

Also check the float needle.  If the tiniest piece of carbon or other contaminate gets underneath the seat on the float needle, the fuel supply into the combustion chamber will never stop, even though the floats are up in the bowl.  After checking this, you can test to make sure the needles are sealing by attaching a hose to the fuel intake side of the carb and GENTLY blow into it.  Air should come out of the float needle area when the floats are lifted, and should stop the air when the floats are dropped.  Keep in mind that there is very little pressure on the floats to stop the fuel so you don't need to go crazy with the air pressure, I've seen most float needles hold until 2-3psi and that's about it.

Since you have one working carb, use that for comparison: make sure all the sizes stamped onto the side of the jets are the same and there are no leaks anywhere.

Try these steps and let us know how it goes, you can PM me if you need more help/guidance.

Thanks,
Josh

Quote from: cerebus on January 06, 2008, 12:58:22 PM
Hey everyone! I'm new to this forum, as well as being a relatively new rider (a little over a year) and I have a question about a problem I'm having with my '92 GS 500E.

For some reason the right side sparkplug gets fouled with black sooty carbon every time I ride her. Of course the performance gets steadily worse until I have to pull the plug & scrub it with a wire brush, and even that only works so many times before I need to get a new plug. Other than that, she seems to work fine.

A friend of mine suggested that the carbs may have some oil sludge in them and need to be replaced or cleaned out, or maybe rebuilt. Others have said that the fuel mixture is too rich and the air/fuel screw needs to be adjusted, some just say I need a newer bike. Unfortunately I'm a poor man (the bike is my transportation 'cause I can't afford a car), but I do have a friend with tools and mechanical know-how (the one who suggested changing the carbs).

Any suggestions as to what I can do to get her running reliably?   

You've already gotten the 'gold' responses, so I'll just comment on your 'friends' technical knowledge.

The one that said you have oil sludge in the carbs, gee, I just don't know where to start. How does oil get into carburetors ? Maybe he's putting two stroke oil in his four stroke bike and thinks everyone else should too ?

The ones that suggested fiddling with mixture screws may actually have done it themselves and know a thing or two.

The guys that said 'you just need a new R1 dude', well, they're lost. I'd almost bet they live on credit, pay exorbitant amounts for insurance on sport bikes they can't handle or control, and won't be riding much longer.

Pick your friends like you pick your nose, carefully, and with a plan in mind

If/when you get it sorted, please update this thread as to what it took, and what you tried. It's always good to have problems solved and the path to the solution.