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81 gs 1100 carb float setting

  • Thread starter Thread starter jamie f
  • Start date Start date
J

jamie f

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i recently aquired a 81 gs 1100.had sat for a few years due to bad running.found bad cdi box and rotted fuel petcock.replaced petcock,installed dyna stand alone ignition,cleaned carbs and it fired right up.runs great in driveway,took it down the street and it bogs down over 2500 rpm's,running out of fuel i suspect.took carbs back off and all four floats are set at different heights.any one have specs/measurements for the float settings?thanks,Jamie
 
Top of this section youll notice pertinent information that has been saved in the form of a STICKY..in fact there are several STICKIES on several sections. Click there and youll most likely find your info.
 
jamie f said:
i recently aquired a 81 gs 1100.had sat for a few years due to bad running.found bad cdi box and rotted fuel petcock.replaced petcock,installed dyna stand alone ignition,cleaned carbs and it fired right up.runs great in driveway,took it down the street and it bogs down over 2500 rpm's,running out of fuel i suspect.took carbs back off and all four floats are set at different heights.any one have specs/measurements for the float settings?thanks,Jamie
Click to expand...


Go here, http://www.mtsac.edu/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf has all the info you need, Look for the float setting info if that is all you want. Though the whole thing is great info for rebuilding your CV Carbs the RIGHT WAY.
 
thanks guys for the info. set floats to spec,reassembled and took it for a drive still acts like its running out of fuel,pull choke and it comes back to life,have cleaned jets,soaked carbs,all new parts.am I overlooking something?i did notice the jet size was 107.5,only spec i found was 115 for 82 gs1100.can that really make that much of a difference?i should mention that it has a 4 into 1 header,unknown brand has been painted flat black from previous owner/no tags on it.i've seen jet kits for it up to 180 but that seems excessive for street use.would appreciate any and all ideas or advice.also have found regulator rectifier very warm to touch and had to repair burnt wires and run grounds to engine and battery thanks,Jamie
 
You have a stock airbox on it or pods? :-k

107.5 is the stock main jet size. Unless your header is seriously corked up, you will need larger jets, maybe in the 115 to 122.5 range, depending on how well the header flows. If you have pods on there, you might need something in the 125 to 135 range.

With your stock-size jets, you ARE running out of fuel.

.
 
thanks steve,appreciate the info!header seems to flow pretty free and snorts pretty good.i am running pods,so i guess ill have to get larger jets.the motor in this bike seems pretty strong,revs to 8000 rpms in a hurry,dont know the history on bike but i had an fj 1100 that didnt rev up quick like this one,possibly built up?in any event,heading to suters speed shop to see about jets. thanks again,you think of anything else please let me know,like i said before any and all advice is appreciated.i will post back with results of 130 jets,by the way should i be changing my pilots also?seems to idle perfectly and doesnt lag when revving up,,,,until it runs out of fuel at higher rpm's
 
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thanks to all of you for the info and advice.installed 127.5 main jets and runs really well now.maybe a slight hesitation mid range but cycle shop didnt have 1 size over stock size pilots,which is what they recomended when i got larger mains.also,apologies for "newbie" mistakes.am now looking more closely at what forums are for what topic/subject.thank you gs resources,great site to be a part of!
 
take a look at the needles if they are adjustable then move the clip down 1 position towards the point of the needle this will richen up your mid range
pilot jet = 0 to 1/4 throttle
needle and needle jet = 1/4 to 3/4 throttle
main jet= 3/4 to wide open throttle

hope that helps you to better fine tune the carbs now that you are in the ball park
 
thanks spyderman, that makes sense, i'll try that tomorrow,and repost back!
 
Spydie is basically correct in that the throttle positions he notes apply more to VM carbs than CV carbs.

Maybe those with CV carbs would find this more helpful and should store it in thier favorites. Note there are several places to click on links in the presentation and at the end there is a database link and his phone numbers to call if need be.

http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html
 
ya chuck i always seem to forget that little tad bit that the CV are a bit different there seems to be more overlap on the circuits than with the VM's so tuning is just that bit different thanks for the reminder
 
great link chuck,i think with that information final tuning should be alot easier.nothing like guesswork on a bike that seems to have been patched together with leftover parts.armed with this info i should be able to get it running perfect.appreciate all the replies and info.very helpful
 
jamie f said:
..., by the way should i be changing my pilots also?
Click to expand...

Generally no need to change the pilot jets.

Look at it this way. Why do you need to change the main jets when you switch to a header and pods? Because you have removed the restrictions that the stock systems impose on the air flow.

Next question: What causes the most restriction to airflow when operating at idle and low-throttle? No, it's not the airbox or the exhaust, it's the throttle butterflies. Since the airflow potential at idle and low throttle settings is virtually unchanged, there is no need to increase the fuel flow.

Now, by the time you start getting into mid-throttle settings, air flow can increase, so you might need to shim the needles a bit to help there.

.
 
thanks steve. that is my next step is to change needle height,lowering clip 1 notch on needles to richen up mid range,and see what that does.first time i have ever had to fix someone else's mistakes on setup and carb adjustments.has been a very learning experience.many thanks to everyone at gs resources.
 
jamie f said:
... my next step is to change needle height,lowering clip 1 notch on needles to richen up mid range,and see what that does. ...
Click to expand...

If you have a US-spec bike, you will only have ONE notch on the needles.

The solution is to get a few very small washers (3mm?) that will equal the height of the thick nylon spacer that is above the clip on the needle. Depending on the thickness of your washers, it is usually 4 or 5. Remove 2 washers off the stack, put the stack of washers in place of the nylon spacer. The thinner "spacer" above the clip will allow the needle to ride a bit higher in its jet.

.
 
thanks steve!i reset needles like you suggested and it runs about perfect!no soft spots on accel right on through to redline,but i am getting a crackle on decel.dont know if its just my header baffle blown out or packing gone.its pretty loud.what would you suggest as to repairing that?new baffle?not sure what brand it is so if you know of a site to go to for finding replacement baffles by diameter size and length please let me know.thanks everyone for all your help!
 
finally recieved my new pods(MOXI brand)installed them and re-packed header muffler(was completely empty)took it for a spin,bike started overfueling at about 3/4 throttle..my first thought,great,,, carbs off again.....pulled carbs removed 127.5 jets,reinstalled 120 jets(keeping some on hand now)reassembled and test drove,just about perfect.this has been a learning experience to say the least.thanks to everyone for the great info and advice,bike would still be on stand without this site.
 
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