running rich

[rookie racer]

ok motorcycle experts !
this was the second time to the suzuki shop for the rich condition[ black plugs]. after $500 and a rejet it runs like crap . pops, wont idle, plugs are still black. iam not taking it back to them.
they put 120 in the main jets, i think 115 is stock size and replace air filter with a k&n in the stock box.
this bike has a vance and hines 4 to one. [the quiet one].
will the 4 single air filters make the bike leaner or a different header work better?
i am scared to tear into the carbs myself, part of me wants to do it but iam intimidated. should i do this myself? is there enough info out there to do this ?
what to do ?

[80-81, GS 1100]

You spent $500 for a rejet but it won't idle?
I learned the hard way that you don't let a mech rejet your
bike unless you know they know what they are doing.
If there is anyone at that shop that is competant I would take it
back and demand they get it right or give me a refund before its too
late.

I had a 1982 KZ1000J2 when I was in the Army that I spent a lot
of money rejetting. The Mechanic never did get it right because
after I moved and was out rideing with friends I blew a hole in a
piston at about 100mph.

Its possible to have it too rich in some ways and too lean in others.
Poppin could be due to either a lean condition, air leak, EPA equipment
that is not hooked up right, or somthing else.

If it were me they would keep the bike till its right or I have my money back, but then again I don't trust any mech in my town to rejet my
carbs, there is a guy an hour away....

Before I rejet carbs I make sure my valves are properly adjusted as
well as the other maintainace things.

Is your model a 2 valve bike and are they mistakeing it for a 4 valve
bike? I'm sure someone will come along who knows. My main point
is don't put a lot of miles on it before its right or your bike may end
up like my KZ.

[tkent02]

If they put in bigger jets to fix a rich condition they are truely clueless. A jet kit is just something expensive to sell you. Usually they will take your money, make it worse and worse until you give up and buy a new bike. Another good GS bites the dust.
That big building didn't get built from guys coming in and spending a few bucks at a time on carbs.
Do it yourself or buy a newer bike.
Find someone who knows the old bikes.
Most likely some local GSers from this board would be happy to help out.

[TheRedlineMan]

Popping sounds like you may be getting air into the exhaust. Check that the header pipes are bolted up correctly and that the joiner pipe and muffler have good seal. Also check the seals on the airbox, that the carburettor mount and manifold rubbers don't have cracks and are seating properly.

Did the shop balance the carbs before re-jetting? Are all plugs the same degree of black?

Let us know how you go. There are others on this site who can help you out better than I can, but ensuring the above points have been checked will make things easier for them and more successful for you.

There are some tutorials on this site on stripping / rebuilding carbs. Would pay to read through them, they'll give you a better understanding of what's going on/wrong.

[Kahuna]

Don't be intimidated. There are alot of wise folks here on this site. I was going through an exerience with my 29's and learned alot. Seach posts for sync or bench sync carbs. Once you know they are in sync then put 4 k&n filters on and then adjust your air screw. Change jets after that if needed.As you already know how to read plugs you should be ok.

[KEITH KRAUSE]

Did you inherit the bike in this condition??
If so, it could be many things causing it to run rich. Who knows what the PO did? The carbs may not even be the right ones, etc.
If you don't want to work on the carbs, then you're limited to what you can check.
A rich condition could be from a weak spark or poor compression too.
Some basics: check compression, valve clearances, spark color/quality, clean all electrical connections including plug caps, check plug type, test coils and ignitor, check advance timing with a gun, check for a clean air filter.
Be sure the bike isn't burning oil.
If all above are checked, and they should be as part of normal maintanance anyway, then you can go at the carbs.
If it is carb related, I suspect they need a good cleaning, float levels checked, and all rubber parts inspected.
After that, install some jetting that makes sense for your mods.
Typically, a quality pipe as you have requires 1 to 2 full sizes richer on the mains. That means 5 to 10 larger than whatever the stock main is. I'd probably try 7.5 larger to start. I'd also add 2.5 for that K&N filter. Totalling 10. Test at full throttle for the main.
Only way to know how the jet needle circuit is mixing is to test at 1/3 throttle. Mid-range flow may not be effected as much as the top end. Do what the plugs/performance say. Yes, while the carbs are apart you could richen the jet needle by raising it a little if you want. It may or may not save time. It's a gamble. If I were inclined to raise the needles for your mods, I'd try about a "1/2" position change, which would be approx' .022" higher. This is just a guess though. Seeing how the plugs burn at 1/3 throttle first is best.
Many times, for your mods, simple richer mixture screw adjustments are all that's needed for the pilot circuit. Again, test at minimal throttle positions.
I doubt you will need to change to a larger pilot jet.
If you didn't replace the header gaskets with the new pipe, don't necessarily blame decel' popping on the jetting.
Be sure to bench synch the throttle valves/plates. This should then be follwed by a vacuum tool synch. No way to accurately gauge performance and plug reads without the carbs vacuum synched well.

[rookie racer]

wow!
i didnt expect this kind of response. thanks everyone! i am new at this bike stuff, i just bought this bike 2 months ago so its been in the shop for a month.
i failed to say in the first post that 2 other people rejeted the carbs and the previous owner has no idea what size jets were installed. he put the header on thinking it would help lean it out. it sill ran rich, blackened the plugs about 50 miles on a fresh set of plugs. it ran great untill 50 miles or so.
then i bought it knowing that it ran a little rich. it ran great on cleaned plugs for about 50 miles or so then it would load up.
so i took it to my home town suzki dealer, they looked it over, fixed a leaking fuel line, changed the air filter[k&n] in the stock box, i think he raised the needles and adjusted pilot jets.
he then said it would load up still after several miles. then they ordered a jet kit, i dont know what size that was ordered.
when i got the bike back sat. it was hard to start, would not idle, missed, jerked,popped,ran like crap.
i dont kwow where to start on this thing , i would like to learn, and would rather rejet this bike myself, but intimidated.
i dont know if its 2 or 4 valve,i really like this bike and want to keep it.
i does not burn oil and i think it is good shape ,
so where do i start?
thanks .
i will try to send i pic of the bike

[ta473]

running rich

where you at in ohio?

[rookie racer]

way south of you 60 miles south of columbus

[rookie racer]

ok guys maybe you are out ridding on this beautiful day.
i ran a compression test , all 4 plugs out, wot.
#1-125
#2-125
#3-120
#4-148
iam going to call the mech. tommorrow a try and find out a little more info on what he did.
the bike pops on acceleration, its worse than before i took it in the begining.
i cleaned the plugs with wire brush and followed with acetone, installed, then took a ride, still no change, black plugs. HELP !

[80-81, GS 1100]

Your pretty sure your valve are adjusted? Not saying
thats your problem but its a waste of time doing a
compression test with tight valves......

It would be a shame to throw more money at it and
burn your valves....

[rookie racer]

no iam not sure the valves are adjusted,the bike ran great when i first bought it other than plugs blackening, but no noise from the valve train.

[KEITH KRAUSE]

OK. All the basics I mentioned before should still be done, but because of all the carb work done recently, I'll focus on the jetting. Your description of what has lead to black plugs sure sounds like someone isn't jetting it right. I can't promise to get the jetting right the first try, and with the jet kit installed, the new jet needle (?) could take some tinkering to get right. It would help if we knew what stage jet kit the mechanic installed. Surely it is written down on a receipt or he can tell you how he decided on this jet kit?? If possible, ask if any other carb work was done such as drilling out the vacuum orifices to the diaphragm chamber/piston assembly or installing restrictors, installing different air jets, etc. If he installed a stage 3 kit for your mods, it won't work.
I'm trying to consider your carb experience. Either way you go at this you'll have to get inside the carbs.
With jetting, you have to remember you have 3 basic jetting circuits. Each circuit regulates the mixture at certain throttle positions. The pilot jet regulates approx' idle to 1/4 throttle position. The jet needle approx' 1/4 to 3/4, and the main from 3/4 to full throttle. There can be significant overlap between all circuits but those are the basics. You don't change a main jet for any problem other than 3/4 to full. You don't change a pilot jet for a WOT problem, etc.
If the bike runs poorly at pretty much all throttle positions, then you need to open up the carbs without any testing and see what jetting you have. But if it runs well enough at certain throttle positions, then test at approx' 35/40 mph steady cruise in 4th/5th gear and chop off and read the plugs (pilot circuit test). Next, test at 1/3 to 1/2 throttle position in top gear (jet needle test), then test at full throttle (main jet test).
After doing this, you will then have an idea of what all circuits are doing and what changes you'll need to make when the carbs are apart. Be sure the bike is fully warmed up before all tests. The bike must be under a certain amount of load when testing. No downhill testing.
Either way, you'll need to tell us what position the jet needle e-clip is in (the kit would include an adjustable jet needle?) and what size main jet and pilot jet are installed. You also need to carefully turn in the mixture screws (keeping a record of their position) and let us know where they are. The float levels will need to be measured too.
With that info and the plug reads, we can re-jet.
I know it sounds like a lot of work but I've always found that the best way is to check all the basic tuning items first, then concentrate on the jetting. You'll need good fitting tools and a decent manual. To do all carb work you'll also need a vacuum synch gauge. There is a lot of help here if you ask. There is a helpful CV carb section here too. Ask lots of questions before getting into something you don't understand. You can do this if you have patience. You've already seen what so-called mechanics will do for you.
Let me back up a bit and say to be careful with high speed testing. I'm lucky because I have a great area to test in relative safety from traffic and even the police. You may not be as lucky. I can only share the way I test. Without a Dyno, the most accurate way is how I described above, which is operating the bike on a specific circuit at a specific throttle position. Take a rag and a snug fitting piece of tubing that slips over the plug end to help remove and install hot plugs. Be careful of cross-threading.

[Steve]

way south of you 60 miles south of columbus

OK, so you are 60 miles south of Columbus. Which side of 23? The west side of 23 is withing tinkering distance for me.
Might be able to come over some time before the snow flies and have a look-see with you.


.

[rookie racer]

steve
iam west side of 23, off of 104. pm me .
thanks!
scott