New here , just snagged a 1980 xs1100

[bikerphil]

On your offending carb(s), try setting the float height 2mm richer (lower them with the carbs upside down), and see what happens. Only thing left I can think of.

[XJOK2PLAY]

Td7...

While I can definitely feel your pain and frustration here, buddy... I offer this...
If it were me, and knowing me, my skill, my patience, and my overwhelming desire to get this thing running so I could finally ride it...
If swapping 1&2 carbs to 3&4 fixes it... and swapping all parts between the carbs won't identify it, one must resolve that carb bodies 3&4 must have some weird problem. Maybe it's time to try to locate 2 more KNOWN GOOD carbs from sombody, and try that. Sometimes... the problems can just elude us, no matter what we try.
But I gotta say, some of the best minds on here have given it their all.
IMHO... you ALL oughta get an award for tryin'... and TD7, you should get one for patience and persistance! I just want you to feel the real XSiveness these bikes deliver... and soon! You deserve it!!! Sorry your first experience has become such a PITA. Good luck, buddy. Trust me, when you finally get it right, it will be worth all the trouble, and look how much you've learned about the insides of these carbs! No one can take that knowledge away from you! Before long, (after you fix yours and she's running sweet), another new member may post with very similar problems... and look how you'll be able to say, "I had a similar experience with mine, this is what I did..." That's what makes this such a great site.
Regards,
Bob

[TDodge7]

the only thing i can think of is maybe there's crud inside the pilot passage that isn't completely blocking off the passage , but maybe slightly limits flow and for whatever reason that causes it not to run . but you'd think with all the compressed air (and this is a BIG compressor) and carb cleaner anything in there would have been blasted out . i could try sending a pipe cleaner thru there or something i guess . someone from this board is going to let me try a spare set of their carbs in a week or two so we'll see how that goes .

[XJOK2PLAY]

Spare carbs...

If they're good ones, I bet she'll scream like a banshee! (The bike I mean...Ahem.)

[petejw]

have you worked out by the plugs, whether ur running rich or lean?
As Ken said, check out the choke plunges, at the end of the plunger is a rubber seal, if the seals are worn fuel will seap pass and make the cylinder run rich, this happened to me with the number 1 carb. JAT.

[scalded dog]

TD7, while cleaning the carbs on the special I just picked up, I noticed the plungers on the float needles were not working, they should push in and out easily, as they are spring loaded, I've blasted them with wd-40 and carb cleaner, only got one working so far, will be working on that today my self, just a thought. Later 'Dog

[TDodge7]

all the little plungers are free and springy . i haven't looked at plug 4 because it's a brand new plug and that cylinder is only running 1/8 of the time , i don't think it'll tell me much . if the choke was leaking then the bike would probably idle , that cylinder kicks on as soon as i give it choke and it gets some extra gas .

[3Phase]

well i still haven't fixed it . but i wish i'd thought of shifting the carbs over 2 spots before i bothered messing with all the other stuff . i wonder what the hell is clogging my pilot circuit . if i put my finger over the starter air jet cylinder 4 starts right up , so there's gotta be something in there .

If you are actually blocking the start circuit air jet then it looks like there is a leak somewhere between the start circuit and the pilot circuit.

What happens if you put your finger over the starter air jets in the #1 and #2 carburetors? Do they stumble and run rich or pop and run lean?


Regards,

Scott

[TDodge7]

if i put my finger over the starter air jet on carb#4 then it starts right up , cylinder 3 seems to run at least half of the time , putting my finger over the starter jet on carb#3 doesn't seem to have as much affect as it does on carb#4 . i haven't tried carb 1 and 2 , i will soon and report back .

[TDodge7]

i tried putting my finger over the starter air jets on carb 1 and 2 while it's warmed up , it makes the engine slow down and stall out , but then again it is also only running on 2 or 3 cylinders , so it doesn't take much to stall this thing out .

[3Phase]

i tried putting my finger over the starter air jets on carb 1 and 2 while it's warmed up , it makes the engine slow down and stall out , but then again it is also only running on 2 or 3 cylinders , so it doesn't take much to stall this thing out .

So, with the enrichener off, #1 and #2 go rich and stall when you block the start air jet.

Are you sure that you're not blocking the pilot air jet? The pilot air jet is on the lower left side of the inlet bell and the start air jet is on the lower right side.


Regards,

Scott

[TDodge7]

my mistake , it is the lower left jet so it's the pilot air , i mixed the names up .

[TDodge7]

oh , and i just tried the propane test , i can't get the engine to change rpm at all with propane , tried all the way around the boots and between the carbs , and at the ends of the butterfly shaft .

[3Phase]

oh , and i just tried the propane test , i can't get the engine to change rpm at all with propane , tried all the way around the boots and between the carbs , and at the ends of the butterfly shaft .

Okay, if the two problem carburetors run better when you block the pilot air jet then they're running too lean with no external leaks. There aren't a whole lot of things it can be:-

1) The pilot air or fuel jets (or both) are wrong

2) The pilot circuit has an extra hole in it somewhere -- an internal air leak

3) The fuel level in the float bowl is too low

Sorry, I know you've gone over this stuff time and time again but that's all I can think of for now!


Regards,

Scott

[TDodge7]

the jets were all what the book said a 1980 model should have (if i remember right 110 mains , 42.5 pilots , 108? or 180? pilot air jets ). the guy i got it from had just stopped riding it because he bought a harley , so it's just been sitting in a garage . the floats are set to 23.5mm if i remember correctly , which is what it said in the manual and what cylinder 1&2 are running fine on . i'm not sure what could be leaking internally .externally i couldn't get the engine to rev up with starting fluid , carb cleaner , or propane . the sync caps on the boots are new . the o-rings on the mixture screws aren't new but i switched them with carb 1&2 just to make sure and of course carb 1 and 2 still work . and it seems all the carbs like to randomly puff a mist of gas out the back every time the engine hiccups (which is pretty often) . this is by far the most annoying rack of carbs i've ever had to mess with . short of maybe an ultrasonic cleaning or just straight up getting another rack of carbs i'm not sure what else can be done .

just so i know is there any reason i couldn't use another year carbs ? i know the earlier ones have capped pilot jets because they draw from the larger main jet , but it should pretty much still be plug and play right ?