New here , just snagged a 1980 xs1100

[TDodge7]

i haven't synched them yet ,the place i ordered my synch gauge from was out of them , so now i'm waiting for my morgan carbtune to get here from the uk . but you'd think even with horrible synch it would still try and run . i haven't tried putting # 3 & 4 into the #1 & 2 boots yet , but i doubt it will start at all like that .

is there a part number for the butterfly seals ? i looked on bikebandit and couldn't see any .

[TopCatGr58]

MikesXS.com sells them.

Throttle Butterfly Shaft Seal Throttle Butterfly Shaft Seal -
Fits: Stock Mikuni BS34/BS38 CV Carbs on all 1970-84 650's

Part #48-5021 $5.00 USD Pair
***************************************
Throttle Shaft Screws Throttle Butterfly Shaft Screws (Pk./4)

Fits: Stock Mikuni BS34/BS38 CV Carbs. Part #48-5022$2.00 USD Pk/4

JUST DON'T TELL THEM OR ASK THEM ABOUT FITMENT FOR XS1100, they will get very angry and NOT SELL THEM TO YOU!!
T.C.

[TDodge7]

hmmm , well i just sprayed down both of the offending carbs with A LOT of carb cleaner to see if i could get it to rev up from the butterfly shaft . nothing , not even a pop . i just don't get it .

[Ken Talbot]

i haven't synched them yet

Hang on a minute, the carbs are not sync'd? Not even with the rough and dirty bread-tie method? I would suggest trying the bread-tie sybc method while waiting for a real sync tool. Other than that, you would be wasting your time doing anything else. Without sync, you're just shooting in the dark, and all bets are off. Sorry, but it really is that critical, even if it is only the bread tie method.

[TDodge7]

well visually the butterflys are all very close , are these bikes so finicky that not being synched really cause it not to get gas at idle ? i've had bikes before where i had to actually take the carbs off the rack to clean them individually and they would run on all four without a synch .

[Ken Talbot]

It is sounding like the middle adjusting screw, which sets the left side against the right side, is way out of whack. The left side carbs are open so far at idle/low speed, trying to do all the work, while the right side carbs are shut off completely. As you throttle up, the rights finally come to life and away you go.

Another remote possibility might be the middle adjuster itself. It looks like this:



The adjusting screw is in a "C" shaped bit with the screw on the top and a spring on the bottom. A tab from the left sites between the screw and the spring. This tab runs the left side butterflies. A similar apparatus sets #1 to #2, and another sets #3 to #4. This is how sync is done. If this stuff has been taken apart, it would not be impossible to put back together wrong.

Things okay in this department with your bank of carbs?

[TDodge7]

how out of whack would it have to be to do what you describe ? would it be visually noticable ? because all the butterflys look the same to me , it's not like 2 butterflys are wide open . if they're different at all it's by a hundredth of an inch or so , thats how close they are .

and my adjusters looks exactly like yours do in the picture .

[TDodge7]

i talked with the previous owner again (owner since 1993) and he says he never had the carbs seperated from the rack , just a cleaning when it needed it , it ran when he bought it and continued to run until he stopped riding it 3 or 4 years ago when he bought his harley . then it just sat in his garage . so aside from me pulling the carbs to clean them they haven't been messed with . i would love for it to just be a clog somewhere but i really can't see anywhere thats clogged . when i put compressed air into the carbs that work i get it out of the same places i get it from on the carbs that don't work . every passage is clear . i'll try to synch it when the carbtune comes in but if that doesn't work then i'm about out of options , i could try ultra sonic cleaning if i buy an unltra sonic cleaner .or i could just buy another rack of carbs and try my luck at that set .

[DiverRay]

I KNOW you have cleaned the carbs a few times, but time to look at them one more time. On the 3&4 carbs, pull the bowls and then blow air up through the VENT system. This is often overlooked, and can cause problems.

[TDodge7]

the 2 vent tubes on the inside of the carb body that exit in the air bell ? yeah , they're both spotless . i'm tearing the carbs down again , i'm going to let them dry out and then bring them in here so i can mess with them while i sit here . this time i'll bread tie synch them and i'll even remove the choke plungers since i didn't do that yet . here goes nothin .

[DGXSER]

FYI,when you remove the choke rod, there are ball bearings with springs behind them on the no 1 and IIRC no 4 sleeves that work the notches of the choke when you pull it. When you pull the rod, make sure you do not let them fly or else see the thread about the hardware eating monster!!

[TDodge7]

well one of the screws broke off when i tried to remove the choke lever , so i'm leaving it as is since the choke works , guess i'll have to drill and tap that out later . i'm quadruple checking all the passages in the carbs , so far i can't see one single reason why these shoudn't work . i just tried a bench synch with a guitar string too but it didn't need any adjustments for all the carbs to match up ......

[TDodge7]

ok , carb cleaning #10

i'm 100% sure that

all main jets are clean
all pilot jets are clean
all starter air jets are clean
all floats are to the right height
all of the needle valves work and seal
all bowl vents are clean
all other carb passages are clean including the 3 little holes near the butterfly
the carbs are bench synched (well bench synch tested since they didn't need any adjusting)
all diaphrams are good
all slide needles are in good shape
all jets in the bowls are clear
i hate carburetors

now at the moment i'm running with no air box at all since these carbs have been needing to come off every 12 seconds . so i'll have to try it with the air box on to be sure . anyway i put the carbs back together (and i mixed all the parts just for the hell of it ) popped the carbs back on , fired it up , and sat back expecting the same old crap . well this time it sounded a little different , not much , but a little . i still get some occasional popping back thru carb #4 but not nearly as much . i ran it full choke , then half choke , and then finally no choke . now when you rev it at no choke and then let go of the throttle it runs on all 4 for a little bit and then slowly loses cylinders . i messed with it for a while and kept revving it . more and more it would idle on more than 2 cylinders . i decided to take it for a spin around the block . it now has power down low , not as much as it probably should , but A LOT more than it did (which i think means it's running on 3 sometimes 4 now) it almost effortlessly rev's up now . so off i went , with the petcocks off so that when i ran out of gas at the end of the street my neighbors would have something to laugh at . once i turned the gas back on and started it up again i was off .....again . this thing has alot of power , i like . so i come back to my house to see how she idles now since it seems to rev and pull no problem . i pull up and it's idling on all 4 , i've never heard it run so well . but then as usual a cylinder dropps off . i put my finger over the starter air jet in the air bell on carb #4 and then it seems to be idling on all 4 again and does so for a while before it needs it again ......so what now ?

[TDodge7]

oh yeah , the only thing i noticed in the carbs that didn't seem 100% right was when i tested the slides to see if they stay up when i lift them and put my finger over their vents . well they all slowly come down with my finger over the vents . 2 went a little faster than the other 2 , but just barely . should they not come down at all ? or when i do that test am i just making sure than none just drop right away ? just to give you an idea it would probably take 20-30 seconds for the fastest slide to make it all the way down with my finger over the vent .

[randy]

Excuse me for not going through and re-reading over 100 posts to find out if this has been covered, but...

Have you done anything with the valves?

Is the exhaust system on 2&3 leaking at the headers or does it have holes in it?