New here , just snagged a 1980 xs1100

[XJOK2PLAY]

Td...

Another question...
BTW, did you do the compression test with wide open throttle, gas turned off, ALL plugs out, engine warmed up?? If not, readings will be effected.
Just another thought...

[TDodge7]

i don't have a compression tester , my friend does , he brought it over the other day and tried all 4 cylinders , gas off , throttle wide open , but the engine was cold because i was working on the carbs , if i remember right they were all around 90-95 cold . but the good running cylinders all have the same compression . and if i just turn the choke on or put my hand over the back of carb 4 then it fires right up .

[TDodge7]

oh , and yes , all the the little jets in the bowls are clean , the carb cleaner straw fits right in the hole and a fine mist sprays out from the other end on all of them.

none of my carb boots are torn all the way thru , i suppose i could just patch them up and save the money for other parts . maybe one of those ultra sonic things i keep seeing , that might come in handy if there's something hiding in my pilot circuit . the boots i was looking at aren't oem they're these http://cgi.ebay.com/ebaymotors/YAMAH...spagenameZWDVW

[DGXSER]

Fairly cheap carb synch mthod I use is a single vauum gage and the PVC plenum described in the tech tips. I just move the tube from one carb to the next and get them reading the same. Works well for me and should certainly get you close enough to prove or eliminate Synch as the cause of this level of problems.

95 PSI is REALLY low, not be insulting you or anything, but are you sure you had the throttle open, have you verified you dont have a ton of stretch in your cable or something that your not ACTUALLY opening the throttle full?JAT

[TDodge7]

the throttle had to be open , because the carbs were on the other side of the room in pieces with me working on them . and the compression tester it's self is old as the hills so i'm sure it's not dead on any more .it's my friends compression tester and he just swung by with it for a minute or two so i had to have him do it then . it showed all 4 cylinders to be in the same range , and the other 3 cylinders run like they should , so it would seem that it has enough compression . especially since when i put my hand over the back of carb 4 that cylinder will fire up .

[TDodge7]

ok , today i threw out the old synch caps and got some new ones , i also got rid of the octopus . it seems to want to run on cylinder 4 a little more today . i'm not sure why . i'll keep messing with it i guess . it's my only chance of riding this summer now that my family has borrowed all but $40 of my money . and when the synch gauge shows up maybe it will help alot ...at least i sure hope it does .

[DGXSER]

Have to agree that is as open as they get

Holding your hand over the inlet bell will decrease the area to draw the air through and therefore increase the velocity around the inlet bell. IIRC these are the later 80-81 style carbs? If that is the case, then the inlet bell holds the starter air jet, the main air jet, and the vent for the carb. So, the increased velocity may be shoving more air into your jets? Maybe causing it to force more fuel in? soo...I'll ask although you seem quite confident in the cleanliness, are you certain the air jet paths are very clean? Did you change the starter air jet in 3 and 4 when you swapped the rest of the jets?

[TDodge7]

when i spray carb cleaner into the hole for the pilot jet the carb cleaner sprays out of the jet on the back side of the carb (the one in the bell on the back that has a flathead slot in it) i didn't bother removing them from the backs of the carbs because i heard they're actually pressed in .

i also never removed the pilot air screws because i didn't want to screw up the tips . should i try removing the pilot air and the starter air jet (provided the starter air is removable)

[DGXSER]

If it were me, I would pull them both just to be sure. both of those assmeblies will effect the idle fuel and air mixture. The Starter air jet is the one in the lower left side as you look at the inlet bell. It has the slotted head and it is screwed in. Soak it in PB Blaster or th elike first, and make sure your screwdrive fits the slot well.

I would also pull out the mixture screw down in that tower on the outlet side of the carb in front of the slide area. Again, if it were me, i'd count how many turns in it takes to VERY LIGHTLY seat the mixture screw in carb 3, then return it back out. I would then remove the screw in no 4, make sure that area is good and clean. After cleaning I'd set it to the same setting as no 3.

Also, remember the spring, and the rubber seal with the little metal washer in there as well, pull them out to. Then you can check the tip to see if it is broken off. Now that you mention it, seems like if that tip were broke off it could be causing the issues? Never had that problem so I do not know how it would react to it.

[TDodge7]

well i took the carbs off again , removed the starter air jets at the back of the carbs , they were all clean . and i took out the mixture screw on carb 3 and 4 since 3 runs half the time and 4 hardly ever runs . the tips wern't broken off , but they did have some gunk on them . i cleaned them , cleaned where they go , and put them back to 1 1/2 turns out which is what carb 1 and 2 are at and they seem to run well . but my whiny old neighbors are hanging out on the side of their house having a tea party or something so i can't go start it yet . the symptoms seems like something in the pilot circuit of carb 3 and 4 now . mainly 4 , and if you can get it to rev then 4 kicks in , otherwise it just sits there missing , popping , or just not running at all .

[TDodge7]

it's totally the carbs , i took the rack of carbs off , and put the left 2 carbs on the right 2 cylinders (no carbs on cylinder 1 and 2 like this ) and guess what , cylinder 3 and 4 fired up and ran perfect . i guess i'm just missing somethin gin the pilot jet somewhere . i'll mess with it more and post my results .

[XJOK2PLAY]

Cool....

Way to go TD! I could tell by reading your posts you knew what you were doing all along!!! Way to stay with it, man. Feels good, don't it???
Good luck!
Bob

[TDodge7]

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 .

[tarzan]

Are you sure you have all the right size jets?

[TDodge7]

yes , they're all the same , 110 mains and 42.5 pilots if i remember the numbers correctly