Carb Problem

[RANCYN]

I CANT KEEP MY XS1100F 79 RUNNING EXCEPT WHEN IT IS CHOKE THEN IT SOUNDS GOOD ,AS SOON AS I START INCHING CHOKE LEVER IN IT DIES.I HAVE HAD THE CARBS APART AND CLEANED EVERY PASSAGE I COULD FIND ,CHECKED FLOAT LEVELS KNOW THEIR FILLING UP WITH GAS , I CAN TAKE THE PLUGS OUT OF BOTTOM OF CARB BOWLS AND ABOUT THE SAME AMOUNT OF GAS RUNS OUT OF ALL OF THEM. COULD IT BE A TIMMING PROBLEM OR IS THERE SOMETHING IM STILL MISSING INTHE CARBS, THANKS RANCYN.

[sixtysix]

Sounds like fuel to me if only at idle. The idle circuit uses the tube that projects down into the bowl and then the fuel goes through a passage to mixture screw. Make sure you blow out the passage in the bowl itself, hole in bottom that comes up in back, hose of carb cleaner fits right in, then blow up the tube and make sure it comes out of mixture (Pilot) screw port. Did you remove everthing in you carb rebuild? Mixture screws? I have seen some that will not idle because the mixture screw tips were broken off in the hole due to over seating them, they need to be seated LIGHTLY. When you have the mixture srews out, shine a light in the bore ans make sure you have an unrestricted hole.

[GsBike]

I have a '79 F and your problem sounds like fuel issue to me too. After you finish what Gary suggests and you put the carbs back on make sure the idle screw is screwed in enough for the bike to idle. The idle screw is the big long screw centrally (and inconveniently) located along the rack of carbs (between #2 and #3) in the back. The process of cleaning the carbs will throw the idle way off. Once the carbs are on and the bike is running on choke, screw the idle screw in untill the RPMs start to creap a bit then turn it down. Once the bike is off choak you will need to then lower the idle.

I hope it's a simple fix.

[scoobes]

carb problem

you should also check that the carb mounting rubbers (part no 2h7-13586-00 left side ,2h7-13596-00right side) have no crakes or splits in.also in side the air filter housing there is the plastic oil separator(part no2h7-14434-01)make sure that is not blocked and not cracked,this caused me the same problem on one of my xs1100.good luck.

[RANCYN]

carb problem

I CLEANED THE MIXTURE SCREW CIRCUIT OUT AND BLEW THROUGH THE BOWL TUBES TO MAKE SURE THEIR CLEAN, WHEN I START IT WITH THE CHOKE FULLY ON I HAVE TO GIVE IT A LITTLE GAS TO MAKE IT RUN. THEN AS I GO UP IN THROTTLE IT MAY TAKE OFF AND REV UP FINE OR TRY AND BOG DOWN TO DIE. THE REASON I MENTIONED THE TIMING WAS I HAD THE CAMS AND CRANK OUT OF TIME AT ONE POINT PUTTING IT BACK TOGETHER BUT IM SURE I GOT IT RIGHT I EMAILED A SERVICE TECH FROM YAMAHA AND TOLD HIM HOW I TIMED IT AND HE SIAD IT WAS RIGHT. IM JUST LOOKIN FOR IDEAS. I DO HAVE SOME CRACKS ON THE OUTSIDE OF THE RUBBER CARB MOUNTS BUT IT DOESNT LOOK LIKE THEY GO ALL THE WAT THROUGH. I CANT SEE ANY CRACKS IN THE TUBES IN SIDE OF AIR CLEANER IS THERE A WAY TO TEST THE TUBES FOR LEAKS? THANKS RANCYN

[TopCatGr58]

Hey there Rancyn,

Glad to see you're able to post after ISABEL, we just got our power back four days ago(many still don't have any), and our cable/tv/internet/phone service a couple days ago.

Well, the tubes going from the carbs to the air filter box are not that critical as far as leaks go, but the ones from carbs to engine ARE. You can get some WD40 or carb cleaner spray and with the engine running, spray around the intake boot and if you hear a change in engine rpm, then you probably have a leaky boot!!! Mine were badly cracked on the outside, but they are double layered, and the inner lining was intact. But I used some plastidip spray to seal up the outer layer for extra insurance since I was on a tight budget and wanted to get it running without shelling out so much $$ for parts, like new boots!!

You spoke of timing, but what you mentioned was valve timing, and like someone said, if the valve timing was off, it wouldn't run! But there is also ignition timing, and that can be adjusted at the timing plate on your model, so you might want to get a timing light and check that. Sorry I can't remember if we talked about your advance unit, just make sure it's working/moving freely, not sticking, the hose connected to it and to the nipple on the #2 carb body.

Are your vacuum slides on your carbs working smoothly, not getting stuck, and did you check them for leaks, putting your finger over the arched hole in the top of the carb throat, filter side AFTER you push up the slide, and then let the slide drop, if it drops very slowly or not at all, then the rubber diaphragms are probably okay, but if the slides drop quickly, then you probably have holes in the diaphragms and will need to be repaired.

Did you gently seat and then turn out the idle mixture screws 1+1/4 turns out on each carb? Do all the butterflies appear to be in about the same position when closed? It still sounds like carb/fuel problem, not getting enough, that's why it wants the choke. Did you allow enough time to let the engine warm up a bit, like 5-10 minutes before trying to put the choke in, and then try the first stage-halfway in, see if it responds to the throttle okay...if bogs it may still not be warmed up enough, until you can get a decent throttle response, then you can push it all the way in. Is the idle set screw, the big one in between #2 and 3 carbs set/ turned in far enough to start to open the butterflies just a little? But if you're idle circuit is truly clean, it should be able to idle once warmed up without having to crack open the butterflies, IIRC! Well, hope this helps, check things out and tell us what you find.
T.C.

[RANCYN]

carb problem

HEY T.C.
THANKS FOR THE REPLY , I WENT OUT TONIGHT AND WORKED ON THE MACHINE A LITTLE CHECKING SOME OF THE THINGS YOU TOLD ME TO CHECK. FIRST I STARTED THE ENGINE ON CHOKE LET IT SET HOLDING THROTTLE A LITTLE WAYS OPEN TO KEEP IT RUNNING. I SPRAYED WD 40 ON THE BOOTS AND THEIR WAS NO CHANGE IN ENGINE. SO I SHUT IT OFF AND ADJUSTED MIXTURES SCREWS LIKE YOU SAID THEN I FIRED IT BACK UP ON CHOKE . IT SEEMED TO RUN SMOOTHER THEN. I TOOK THE COVER OFF OF CRANK TIMIMING PLATE AND WATCH THE ADVANCE WORK UP AND DOWN AS I REVED THE ENGINE UP AND DOWN. I DIDNT HAVE A TIMMING LIGHT TO CHECK TIMMING YET BUT I KNOW THE ADVANCE SEEMS TO BE WORKING PROPERLY. I DIDNT GET TO CHECK THE VACUUM SLIDES YET BUT THEY LOOKED RALLY GOOD WHEN I PUT THE CARBS BACK TOGETHER.THIS ENGINE WAS A GOOD RUNNING ENGINE 15 OR 20 YEARS AGO IT HAS SET AND JUST BEEN TURN OVER EVERY ONCE IN AWHILE . I GUESS THATS WHAT HAPPENS WHEN THINGS SIT AROUND.MY DAD GIVE ME THE MOTORCYCLE SO ID KINDA LIKE TO GET IT RUNNING SOMEDAY. IT NEEDS TIRES AND OTHER COSMETIC THINGS BUT ILL JUST TAKE MY TIME AND GET THINGS AS I NEED THEM! LIKE YOU SAID IM SHORT ON $$$ ALSO. EVERYONE HAS BEEN ALOT OF HELP IN THE CLUB I LL GET IT FIGURED OUT. BACK TO THE PROBLEM I LET THE ENGINE RUN FOR ABOUT TEN MINUTES OR SO ON CHOKE THEN STARTED INCHING CHOKE IN AND IT STARTED SPUTTERING IMEDDIATLY AND THEN PROCEEDED TO QUIT RUNNING. THEN PUT CHOKE BACK ON AND STARTED IT AGAIN. IF YOU CAN THINK OF ANY OTHER THINGS TO CHECK LET ME KNOW!! THANKS RANCYN

[TopCatGr58]

Hey there Rancyn,

Well, I hate to say it, but it sounds like you will need to take the carbs off again for another cleaning. When these carbs sit for a long time, the fuel gets gummed up in all of the little ports and crevices in the flow circuits. When you have the choke out, you are supplying a richer mixture into the throat of the carbs, and so the engine can run, but when you put the choke in, it redirects the flow thru the idle circuit, and your engine is cutting off, which tells me that you aren't getting any/enough fuel and air flow thru your idle circuit.

You stated that you cleaned the idle circuit, but if you only unscrewed the pilot screws from on top of the carbs and sprayed thru there, that wasn't enough. You'll need to turn the carbs over, and on your 79, next to the main jet you should find a screw plug close to the intake/engine side of the carb, opposite the float pin, you need to unscrew that plug, and remove the idle jet from within, and soak it in carb cleaner, and spray thru that opening where you removed the jet to ensure that you can see it spray into the throat of the carb. You might even want to remove the idle/pilot screws first, be careful, there are tiny springs and washers and o-rings on/around the bottom/tip ends of the pilot idle screws or stuck in the hole that they screw into! And when you did your carb cleaning, if you didn't pull the mains and clean the main jet screw/atomizer that sticks up thru the center of the carb, then you'll want to remove them and soak them as well! And since you'll have the carbs off, go ahead and check the vacuum slides as previously described to make sure they are sliding easily, and aren't actually leaking. It's most definitely a fuel supply problem, and many folks have reported having to tear down and reclean their carbs 3 times(the classic triple clean) before they behaved right!!!

BTW, where at in NC are you? Are you near the tidewater area of Va., if so, then I could make a run to where you are and try to help out in person!?

T.C.

PS:....PLEASE, turn off your caps lock, it really is harder to read, and folks will think you are shouting all the time, thanks!!

[RANCYN]

carb problem

Thanks Tc.
i live in raleigh durham so its a little ways away from the coast, ive takin the main jet out and cleaned them good have alittle problem with piolet jets only one will come out so i soaked them real good and could blow air through passages i thought but maybe not ! they are so tight from be in carb that i twisted little brass ears a little , i didnt want to break them so i just tryed to clean them . i know some people drill them out but that sounds scary. well ill pull them back off and try again. thanks Rancyn

[Ken Talbot]

Now we're getting somewhere. Unless you can get all of the various jets out, it is impossible to properly clean these carbs. Soaking them and blowing some air through some of the passages is just not enough, especially for a set of carbs that has sat around for while and got all gummed up. Once you do manage to get things apart, you will be amazed at the amount of cr@& in there.

Have you seen the tip about using an impact driver for removing stuck jets? You may need an adaptor or two to get down to the correct screwdriver bit size, and you want to be sure you have a nice, fresh screwdriver blade, but this is an excellent way to go.

Also, if you cab get your hands on a Dremel tool and a small carbide burr, you can reform the slot on the top of a jet that has had its little ears torn off. I've done this in the past and still been able to reuse the jet.

[scalded dog]

I have a 79 xs 1100 full dress, I think the standard. The clymer manual says to lightly seat the idle mixture screw, and back it out 1 and 1/4 rounds, I have mine backed out 4 and 1/2 rounds, from a different source, what works the best. Thanks 'Dog

[TopCatGr58]

Hey there Dog,

Well, I hope yours don't fall out being turned that many turns out!! The further out, the richer the idle mixture will be. The idle circuit does provide some input into the early and mid throttle range. But this "tuning" is where folks use a Colortune device if I'm correct. after they have synched their vacuum flow to get the butterflies right, then adjust their idle mixture screws using this tuning aid...of which I don't have nor know how to use!

My local bike speed/machine shop suggested 3+1/2 for my Big Bore/Indy filters/4-1 pipes setup, of which I did a while back, but it seems to bog down at the higher altitudes when trying to run in the lower rpms, so I'll be adjusting mine back to about 2...a little richer than the book, but not as rich as suggested, and will be riding in the Ga. Hills in a couple of weeks, and will let you know how it does.

So...you could try the 1+1/4 and see how it idles and transitions thru the rpm range, if you notice a stumble that wasn't there before, or if it doesn't want to idle well, then turn them out some more until it behaves properly!! HTH.
T.C.

[scalded dog]

Thanks T.C., I will see you in those hills, I am about 2hrs south of Suches. My bike has been running fine on top-end since I cleaned the carbs, but low rpms and one is popping pretty good, my other XS/11 pops just a little at low rpms. Thanks for the tip

[scalded dog]

I am stumped, my bike idles higher and higher, as the engine warms up, I saw where someone else had a similar problem and tried all the suggestions listed there, checked cable ti works perfect with a little slack when I turn it loose, I checked for cracks none on the inside, sprayed wd 40 for change in tempo, nothing there, has new cone air filters, which worked fine pryor to cleaning, can the float hight really make it idle up that high, I have never tried to set them, so it seems like it shoud'nt change by just cleaning. one difference, the springs which force the butterflys to close, two had worked off, I put them back on. but this should help keep the buttrflys closed, the idle screw at back, I backed all the way off the butterfly that it opens for idle. please help. thanks 'Dog

[mitch]

Sounds like !

I think you need to start by turning your idle screws to about 2 turns open to start with then,bench sync the carbs, reinstall them. let the bike warm up then adjust the main idle screw after the bike warms up HTH.......................MITCH