New here , just snagged a 1980 xs1100

[DGXSER]

Just for S&Gs check the pilot air jets are the same to? Can't hurt. Otherwise, look for a color picture on here some where from TC of the idle circuit paths and make sure all are open.

[TDodge7]

the air jets are all the same , tho i can't tell if they all say 185 or 105 ....very small numbers . i'll have to see if i can find that diagram , that would be helpful .

[bikerphil]

i'll have to see if i can find that diagram , that would be helpful .

Post # 45 if you haven't found it...

http://www.xs11.com/forum/showthread...diagram&page=3

[TDodge7]

....i spent all day cleaning the carbs for the 10'th time , cleaning stuff i knew was already clean , just for the hell of it . short of removing the carbs from the rack everything removable was removed . every single removable jet clear . the pressed in jets in the bells of the carbs are all clear . every passage in the bell of the carb is clear . every jet in the carb bowls is clear . emulsion tubes are clear . floats set to 23.5mm as per the manual . i removed the mixture screws and all have their tips and all were adjusted to 1 1/4 turns out as per the manual . i sat there with a friend to verify , and using that diagram of the carb passages we put compressed air in and got air out everywhere it was supposed to . all the passages are clear , i'm sure of it now .

the bike doesn't care , it still doesn't run . which makes no sense at all . NONE . if i pull the rack of carbs off and move them over 2 cylinders the good carbs will make the 2 non running cylinders start up and act just like the 2 good cylinders . which completely rules out anything electrical or compression wise . all of the plungers move just fine and none of the diaphrams have any rips or pin holes . all carbs are getting the same ammount of fuel .

with the engine on i can convince the engine to rev and all the cylinders kick on and sound good . at idle cylinder #3 and #4 don't like to run (#3 likes to run a little more than #4) but if you put your finger over the pilot air jet on either carb that cylinder starts idling .

so really .....what the hell ?

[randy]

How is your diaphragm seal at the carb tops? it's common for the lip to get dislodged during assembly. Did you do the 'thumb over the hole' test to see if the diaphragms are not leaking at the lips? I don't know how else to describe the test. Lift the slide and put your thumb over the oblong hole in the inlet bell, release the slide, it should hang there until you release your thumb from the hole.

Sounds like air is leaking through somewhere. That's as good a place as any to check.

[TDodge7]

they all stay up if i lift them and put my finger over the slot . they all drop when i remove my finger . i've even mix matched parts from carb 3 and 4 into carb 1 and 2 and carb 1 and 2 continue to run well . i may have to go back to my original theory of the right two carbs being clogged with magic because they sure as hell aren't clogged with anything else .

[skids]

If you put in new gaskets, are all of the holes punched out? The screens on the petcock risers clear? Screens on the fuel valves clogged?

[TDodge7]

all gasket holes punched , all screens clear .

[Ken Talbot]

Are your fuel lines long enough to allow you to switch how they are feeding the carbs? I.e. - run the line from the left petcock over to feed the T nipple at the bottom between carb #3 and carb #4; run the line from the right petcock over to feed the T nipple at the bottom between carb #1 and carb #2. If they are already plumbed this way, reverse them.

I'm working on the theory that both pairs of carbs seem to work okay, "when they get gas". We're all gonna feel pretty silly if this turns out to be no more than a kinked fuel line, which can usually be avoided bu using longer lines to allow the cross-over type of feed. The stock configuration just invites kinked lines.

[TDodge7]

the fuel lines are very long , i've tried both ways . the carbs always have gas . the right two carbs just don't like to use any at idle for no reason at all .

[DGXSER]

Reaching deep here, did you check the choke assembly on all four also? Your saying when you "plug" the idle air jet with your finger, the cylinder reacts in a positive way? So it must be getting to much air now. A bad choke seal or butterfly seal perhaps is letting air get sucked in? JAT

[3Phase]

cool , thanks . any idea if I can add a kick starter to this bike? I see where it would have been . is it as simple as buying all the kick starter parts from an older bike or did yamaha actually change the engine case when they got rid of the kicker ?

I just added a kicker to my 1980G. The kicker uses 1st gear to turn over and start the engine. The case and clutch cover will accept the kicker assembly but you will also have to add kick gear 2, the inner ratchet wheel and a couple of other parts to kick gear shaft 2.

The 1980 and later models have the inner kick gear 3 installed inside the case on kick shaft 2 but not the outer kick gear 2, the inner ratchet wheel or the spring clip. If you just add the kicker and a case seal it will look cool, kick nicely and it won't leak oil but it won't actually engage anything to turn over and start the engine.

Go to http://www.yamaha-motor.com/sport/parts/home.aspx and select the parts catalog for a 1978 or 1979 XS1100, then look at the "Kick Starter" catagory to see the parts diagram.


Regards,

Scott

[TDodge7]

Reaching deep here, did you check the choke assembly on all four also? Your saying when you "plug" the idle air jet with your finger, the cylinder reacts in a positive way? So it must be getting to much air now. A bad choke seal or butterfly seal perhaps is letting air get sucked in? JAT

with the slides removed and the choke open you can see into the little ports , everything in there looked spotless but i didn't remove the choke plungers . when you say butterfly seal are you talking about the little o-ring or whatever at the very end of the shaft the butterflys are screwed to ? it's possible that could be bad , but i'm not running on cylinder 3 most of the time either . so if it was the butterfly seal would that make cylinder 3 not run too ? . when the choke is on all 4 cylinders run , so you might be onto something with the too much air thing . at first i thought it would be the cracked up carb boots , but when i moved the carbs over 2 cylinders #3 & #4 ran fine so it's not the boots . how do i check for the butterfly seal ? once i get some of my loaned money back i could probably buy another rack of carbs , or atleast 4 rebuild kits . this is oficially the wost time i've ever had with carbs . and i've cleaned some bad ones before .

[DGXSER]

The only way I would know to check the shaft seals on the butterflys is what I have read here, which is to use an unlit propane torch and point the tip around the shafts with the bike running and see if it revs up. Or spray carb cleaner at them as well.

I may have missed this before about it running better or fine with the choke on. Then choke off runs poorly. But basically you move the carbs and the problem moves with it. I'm leaning back to a synch issue myself. Either that or you have a really damaged carb body somehow. But what would get damaged that you have not seen or how is beyond my knowledge. I know you have indicated you synched these things up already, but just for S&Gs I'd use one vacuum gage and move it carb to carb to synch them up so you know there is no derivation in gage readings. It sure can not hurt to try it.

On the plus side, you know you only need two carbs if you replace, which means you can go to the bone yard and perhaps find a set from the right year of XS650 (much more plentiful) and possibly much cheaper. My local MC junkyard wanted $200 for an as-is set of four for an 1100 that had not been cleaned. This time of year they said the least they would take is $300.

[Ken Talbot]

Interesting diagnosing trick, that idea of moving the carbs over and the way you were able to get #1 and #2 to run cylinders #3 and #4. By chance, did you try it the other way, i.e. seeing if carbs #3 and #4 would spark up cylinders #1 and #2?