#2 Cylinder running rich

I think I know the answer but just want to be sure. Pulled the carbs to reclean the pilot jets and re-bench sync got them cleaned and sync'ed. Reinstalled them vac. sync'ed got them as close to perfect as you can get them. Starts right up with very little choke cold idles great after warm up. Starts in about a second after warm. Started the color tune #1 went fine went to #2 pulled the plug it was black put the color tune in and it was burning blue turned the screw out until it was completely out of the seat no change in color. Turned it back in until soft seat no change in idle. I am thinking all I need to do is pull the mixture screw out and clean the port. Thats the only thing I can think of since it is not getting any air into the mix. Cylinders 3&4 Color tuned fine.

 

No air leaks and compression good. Check all the pilot circuit passages in the carb body. It might be a chunk of crud in there.

Fuel drys out and its like concrete in there. Good Luck and let us know what you find

MN

 

Leak in #2 boot ?

 

No air leaks that was the first thing I checked as soon as it started just went thru the shaft seal leaking and has good compression. It leans out and plug chop is good. It is not getting any air thru the mixture screw at idle. I just cleaned the pilot circut on that carb and replaced the pilot jet due to it being packed with crud I couldnt get to loosen up. It is getting plenty of fuel. I am thinking some crud broke loose and plugged the air ilet.

 

I give up pulled the carbs again. Found all passages clean all jets clean. Floats set right no air leaks. Starts right up with no choke idles at 1100 rpms smooth. Good throttle response cylinders 1,3,4 colortune fine but the #2 is still rich plug is black. Put new plugs in and it still turns black. Ran it without the idle mixture screw in and it was still rich and the colortune was still blue. Put the screw back in and turned it all the way in until soft seat and it finally changed colors. I am about at my wits end with this thing and considering sell it for junk iron.

 

Is it possible the float for that carb is sticking?

 

I checked that again repolished the bore remeasured and wet set the floats. All are correct. reinstalled the carbs and to be sure did a wet check again to make sure it wasnt stuck. Wet check was right on the money. Fired it up started right up no choke idled alittle rough until warm idle settled down. Did a vac sync all are within a 32nd of being dead nut. Started colortune with the number 1 cylinder turned the screw out until it turned orange then turned it back in until it turned blue. Went to the number 2 cylinder turned the screw all the way out of the seat no color change shut the bike down and took the screw spring washer and rubber gasket completely out refired the bike still blue as ever. Was thinking the float is still to high readjusted the float to drop the fuel level lower. refired still blue without the screw in there. Replaced the screw went all the way down to soft seat before it changed colors turned it about 1/2 turn out and the colortune turned blue. Pulled the new plug black as the ace of spades.Put the tank and seat on took it for a spin pulled great thru all gears did a plug chop at 5k and it looked normal nice lt brown. I dont know what else to check or do to correct the problem.

 

What about spark? Perhaps weak spark, not getting complete detonation?

(Just throwing out ideas)

 

checked that also spark is real strong. i even swapped the coils around just to be sure. I have gone thru everything I have read in the forums about running rich or cylinder running cool and tried it all.

 

I have another bank of carbs that need to be cleaned and rebuilt I am considering rebuilding the number two carb and put it on just for chits and giggles and see what that does.

 

I am going to drop the fuel level a tad lower in the morning and see how that works.

 

Hmm.... might be easier just to rebuild the other set and throw it on. If nothing else, you can probably sell them pretty high

 

No doubt the 1100 carbs arent easy to come by.

 

I am in the same situation on my police bike. The third is rich no matter what I do with the adjustment screw. Only thing is, I haven't gone through the carbs yet, I had a mechanic do it when I first got the bike. Fortunately I have 4 or 5 racks of carbs in various conditions.

 

Sure it is , check the enrichment plunger and the jet needle. Have you checked you valve adjustment yet?

 

yes all the valves are well with in spec they are right in the middle of the adjustment. i just read that about the enrichment plunger not closing all the way. I will check that in the morning.

 

You would think if the color tune is blue the mixture would be ok. rich would be orange/yellow. It should respond to the mixture screw. there has to something still in that carb or one big vacuum leak

 

Im going to check the the choke plungers thats the only thing I have not checked. But that would explain it not responding to the mixture screw if it wasnt closed all the way.

 

Took everything back apart checked every single port,jet,orfice found all clear. put everything back together. Bench sync'ed, vacuum sync'ed. It starts without the choke idles at about 800 rpm's with the idle adjustment not even touching. Checked every single place there could be a vacuum leak found no leaks. Quick throttle response #2 still burning rich at idle. It runs to good for something bad to be wrong with it so i am just going to leave it as is and ride it like I stole it. Well I almost stole it got it free because they thought there was alot wrong with it.

 

Lol, nice Hardlucktx! Can't beat that! Could there be some bad threads in that mixture screw hole that's keeping it from going all the way up or down? I'd count revolutions compared to the other screws and see.

 

Set them all at 2.5 out and all are within a slight turn of each other. I cant figure it out so I am not going to worry about it any more . Now it's putting a new rear tire on riding it until I decide what color to paint it.

 

There ya go, make it safe and ride the piss out of it! Is that 1100 pretty powerful? A buddy of mine had he thinks an '80 XS 1100 special, and he was like "man, you wouldn't believe how fun and powerful that bike was," lol, so I was kind of wondering.

 

It runs like a scalded cat. Gets real fun between 5&7K. I am afraid to really hit it hard until 3rd gear due to the second gear problem these bike have. When 3rd gear winds up its on the torque pulls your back on the seat.

 

wouldnt hurt to check your compression as well, a low cylinder wont correctly burn the fuel.

 

Hardluck so you did not find a problem with the carbs try switching the plug wires on 2 and 3 if they will reach

 

Gents, we're all overlooking the obvious. You said the plug is "black." We're all assuming a rich condition, but all of your efforts indicate otherwise.

It could just be a valve stem seal starting to go, and you're burning a minor amount of oil in that cylinder. You're not going to see smoke out the pipe from a valve stem seal until it becomes extreme. Just an increasingly black plug.

Quite honestly, I'm surprised we don't see more valve stem seal issues; it's one of the most common issues with old British bikes.

 

Ok it is a fuel problem. Rode it about 40 miles today. Ran great the 5&7k plug chops look good. Got home and put it on the center stand restarted it went in the house to get a Dr Pepper talked to the wife about 2 minutes or so came back out and it was running rough. Killed it and pulled the #2 plug it was fuel fouled gas was dripping off of the plug. Drained the bowls one at a time and got a higher fuel level from the #2 carb pulled the carbs and found the #2 float sticking a bit. So I broke them all down again for another cleaning. Hopefully when I put them back together it will solve the issues I am having. Does anyone know if there is a aftermaket non-vacuum petcock for the XJ1100. I hate the spider web of fuel lines on this bike.