Running on one cylinder...Can't figure it out PLEASE HELP

[dastardly_dog]

After tearing into my 96 GS to find out why I have a weird idle and hanging rev's, I decided to do a carb sync. I found it to be off but not that bad. I squared it up and it ran worse. Hanging Idle and out of control rev's. I would have to either hit the kill switch or adjust my idle screw to get the rev's down. I checked the choke and its not sticking. I un-sync the carbs to favor  the right cylinder and all is good no hanging rev's idle is smooth SOOOOO I remove my left side spark plug cable and bike runs on right cylinder ok. I switch to the left cylinder and it is hard to start and acts like its flooded. When I do manage to get it to run on the left cylinder it runs for a few seconds and then it dies. Tight valves


what I have done:

Super clean my carbs in every freakin nook I found, soaked in WD and cleaned every jet with Guitar string and compressed air.

air mix screws 3 turns, 3 1/2, 4. 4 1/2

jets are 40 and 150 tried 1 washer and 2 washers under needle

Lunch box and custom wide open exhaust shorty baffle.

checked throttle and choke cables for hangs and found none

check for leaks around carbs and boots and found none

checked compression and spark and have both. Not sure on psi but seems to be the same on both sides

floats height is good tried everything from 13.6 - 15.6 mm..... I stuck with 14.7

bypassed lower petcock with little improvement. with inline filter because tank filter has been removed due to damage. filter is clean.

So yes it is time to reach out to the best of the best and find a fix before the wifey tries to make me part it out

[tialloydragon]

Check your valve clearances and adjust accordingly. 

Check your exhaust headers for leaks around the gaskets.

What do your plugs look like?  Have you replaced them recently?

When you start the bike, does one side heat up faster than the other?

[ATLRIDER]

Hey there,

Just some thoughts of what I'd look at as it sounds like it's running lean on the pilot circuit.

When you put the carbs back together, how were the little orings that go under the plastic covers at top of carbs?

On the fuel mixture screws, are the little orings and the tips of the screws in there in good shape?   Turning screws inward=lean  Outward= richer

Where you able to confirm float level using a clear tube hooked to the carb drain screws?

Good luck

[dastardly_dog]

Check your valve clearances and adjust accordingly. 

Check your exhaust headers for leaks around the gaskets.

What do your plugs look like?  Have you replaced them recently?

When you start the bike, does one side heat up faster than the other?

No leaks from what I can tell. Any pointers?

plugs look good but far from new.

cant really tell with out a inferred thermometer.

  Clearances were off by allot on my tappets.

Left IN had  .076mm  .260 shim
Left EX had  .000mm  .270 shim
Right IN had .000mm  .270 shim
Right EX had .000mm  .268 shim

I had some extra shims    and put them in. all .265 with .07mm Clearances now.
I will button her up tomorrow.

[dastardly_dog]

Hey there,

Just some thoughts of what I'd look at as it sounds like it's running lean on the pilot circuit.

When you put the carbs back together, how were the little orings that go under the plastic covers at top of carbs?

On the fuel mixture screws, are the little orings and the tips of the screws in there in good shape?   Turning screws inward=lean  Outward= richer

Where you able to confirm float level using a clear tube hooked to the carb drain screws?

Good luck

Thanks for your help, All my o-rings are good. float heights are good. I did make the mistake of not paying attention the first time and lost one of the o-rings that go under the diaphragm cap. That was a stressful mistake. Wont do that again.

[slipperymongoose]

Try some fresh fuel, I've had similar problems with mine and the shop said the fuel in my tank was contaminated. 

[ramennoodles]

Also check electrical if still not running right.  When my bike started running on one cylinder, I though I had a bad coil or something.  Swapped coils around and still not firing in the same cylinder.  It turned out to be a corroded wire connector by the battery area.  So I went and cleaned all my connections one by one with wd-40.  It fixed the problem and it never came back.

[the mole]

plugs look good but far from new. Just start with the basics, get some new ones

cant really tell with out a inferred thermometer. Use a finger. If nothing happens, its cold. If your mouth says "OW!" its hot.

[gsJack]

Could well be a carb problem as suggsted above but could also be as simple as a spark plug wire loose in the coil, I've had that problem.  When new the plug wires are screwed into the coils and bonded tightly in place.  Check to make sure the plug wires are tight in both coils and can't be turned by hand with considerable effort.  If loose just cut off about 1/4" and screw it in tight, best to put a big dab of dielectric grease on it before screwing it in.  I had a loose one on my 02 GS and I trim it or replace it about once a year when I check valves.  A loose misfiring plug wire can look like a carb problem with the resulting unburned fuel.

[dastardly_dog]

Thanks guys for all of your suggestions they helped big time. After buttoning her up and getting valves adjusted She runs 100 times better, Still have a slight hanging idle only when she gets nice and hot tho. Does this sound like a lean condition? Remember shorty muff. w/ about 8 in. of baffle, 40/150 jets, stock needles, 1 washer under needle, and 3 turns out. o yea carbs are sync'd. and idle set to 11 to 1200 rpm's BTW I can provide vid if needed or wanted. She's a beast.