Runs well but plugs are sooty black. Why? (GS1000 G)

[Vloukole]

Hi guys

This is my first post as Im new to the forum.
Ive got a little problem with my carbs. Im struggling to determine why my plugs are black. The pilot screws are 2 turns out and my jet needles are set to the highest notch (lean). The bike runs very well. Easy to start.

I think the needle could have some damage cause the P O did not install an air filter and when I cleaned it, it had a lot of sand in the box.

Do you think thats the problem?
Did anyone else have this problem?

 

[GSX1000E]

One thing to check is that your petcock is not flooding the carbs through the vacuum tube. See if it contains fuel instead of nothing.

 

[Vloukole]

The petcock is working fine.

 

[Joe Guilbeau]

Turn those pilot air screws 2 1/2 turns and see if that helps. Also check that the floats are spot on as spec'd.

This link will help...

http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

 

[BigD_83]

For me, I'm not convinced that a dirty/damaged filter would equally affect all four carbs. There are a variety of reasons why you might be getting sooty plugs, but why don't you poke your head into this thread on the same question?

http://www.thegsresources.com/_forum/showthread.php?227010-Running-lean-with-sooty-plugs

Tell us more about your motorcycle. How long have you had it, what maintenance have you done, what modifications have been made to the fuel/electrics/exhaust systems?

 

[Eli69]

possibly bad valve stem seals? cylinder #4 on my bike gets a sooty plug and burns a bit of oil and i think that's what is happening there. that's all i got...

 

[Steve]

Hi guys

This is my first post as Im new to the forum.
Ive got a little problem with my carbs. Im struggling to determine why my plugs are black. The pilot screws are 2 turns out and my jet needles are set to the highest notch (lean). The bike runs very well. Easy to start.

I think the needle could have some damage cause the P O did not install an air filter and when I cleaned it, it had a lot of sand in the box.

Do you think thats the problem?
Did anyone else have this problem?

I am going to start by asking "where are you?"

Your post says "1000G", which started in the 1980 model year. Here, in the USA, we had the CV-type carbs (BS series), which did not have adjustable needles. If you are not in the USA, you might have VM carbs with adjustable needles, or you have a jet kit in there for pods and/or a pipe.

We need some more details, please. ray:

.

 

[chuck hahn]

Steve beat me to the punch..yes we need full disclosure. But I am betting on them being CV carbs. Go to the STICKYs above and select the CV carb tuning proceedures. 2 out is the baseline starting point for the mixture screws. Still rich..you can drop the needles down by moving the clips up one notch and going 1 smaller on the main and pilot jets.

Check out the tutorial first.

 

[chuck hahn]

Choke plungers not closing FULLY will also be a contributing factor. And the condition of the rubber in the tips will allow fuel seepage if they are dry and cracked.

 

[Vloukole]

I bought the bike 3 weeks ago. The bike shop gave it a service last week. They did not clean the carbs or did any tuning.

I am from South Africa. The bike has got 4 into 1 pipes and stock airbox.

When I turn the pilot screws 0,5 turn in, the bike starts to stumble when accelerating.

 

[Vloukole]

The needles are at their lowest position.

 

[Steve]

The needles are at their lowest position.

Depending on the flow characteristics of the pipe, you might need main jets that are 2-4 sizes larger than stock, all the other settings should remain pretty much stock.

I think that if you return everything to stock settings (except the main jets), you will at least have a decent baseline and can make educated guesses from there.

Having the needles in their lowest position goes against all normal logic, as they typically need to be raised a notch for adding a pipe.

Start with CLEAN carbs. "Clean" means inside, not outside, although having the outside clean does help aesthetics. Don't trust a "shop" to do a proper job, you likely have to do it yourself. Adjust for proper float height. Verify all other jet sizes. Set the pilot (mixture) screws to 3 turns out, as a starting point. Set the needles 1 notch higher than stock. If necessary, get new main jets. It is possible that a well-intentioned 'mechanic' has drilled out the jets, leading you to believe the numbers that are printed on them, although it's the wrong hole size.

.

 

[Vloukole]

The bike is running rich. Why do you want me to go larger on the main jets and lift the needles that will make it richer??

 

[Steve]

The suggestion was for "larger than STOCK", but you have not yet mentioned what jets are in there.

The MAIN recommendation is to start from a known point, which would be stock, with allowances for your pipe. Since you admit that the shop did nothing to the carbs, you really have NO idea what is in the carbs, unless you have done it yourself. If you have done it yourself, it will be an easy task to go back and verify all the settings.

First set the float height, then verify all the jet sizes. If your float height is too high, EVERY circuit will tend to run lean, in spite of needle clip setting, so please start from a known setting that is close to stock.

Also, what spark plugs are you using?

.

 

[GSX1000E]

Depending on the flow characteristics of the pipe, you might need main jets that are 2-4 sizes larger than stock, all the other settings should remain pretty much stock.

I think that if you return everything to stock settings (except the main jets), you will at least have a decent baseline and can make educated guesses from there.

Having the needles in their lowest position goes against all normal logic, as they typically need to be raised a notch for adding a pipe.

Start with CLEAN carbs. "Clean" means inside, not outside, although having the outside clean does help aesthetics. Don't trust a "shop" to do a proper job, you likely have to do it yourself. Adjust for proper float height. Verify all other jet sizes. Set the pilot (mixture) screws to 3 turns out, as a starting point. Set the needles 1 notch higher than stock. If necessary, get new main jets. It is possible that a well-intentioned 'mechanic' has drilled out the jets, leading you to believe the numbers that are printed on them, although it's the wrong hole size.

Note what is in bold print. As stated, start with known sizes. You should not have to raise the needle jet or lower it from stock typically.

 

[Steve]

You should not have to raise the needle jet or lower it from stock typically.

Usually not with just a pipe, but by the time you add pods, it is common to raise the needle a bit.

The OP has stated that he has the clip in the highest position to drop the needle to its lowest position, but the plugs are still black, making it look like it's running rich.

Let's go to a known starting place (basically stock, but making allowance for the pipe with larger main jets) and some proper spark plugs, because we still don't know what is being used there.

.

 

[Vloukole]

I use B7es plugs. Tried one range hotter to maybe burn of the soot.
I will check the float height. Will a too low float level make the bike run rich through the whole rev range?

 

[Vloukole]

Do you know what the stock jet sizes are? Main? Pilot? Needle? Etc

 

[BigD_83]

Will a too low float level make the bike run rich through the whole rev range?

Yes. Especially if you are missing the rubber plugs that cover the pilot jet.

 

[BigD_83]

If you haven't been yet, a virtual treasure trove of all things GS related. Here's a direct link to the carb spec page. It's missing the non-North American specs, but it'll give you an idea of where you should be relative to stock.

http://members.dslextreme.com/users/bikecliff/images/carbspec_float_height.html

EDIT- I just saw that there are 1000G specs for RSA...you're in luck