Why would it die?

[petejw]

nice work ridinghard in diagnosing
ur problem.
once ur bike has warmed up properly
everything expands, this results in the
valve/s staying open if they are incorrectly adjusted.

[boncrs]

Me Too

I have the same bike doing the exactly same thing. I found that pulling the plug wires off one at a time cyl 1,2 & 4 is noticeable when pulled #3 there is no difference, when checking for spark all 4 have good spark even when plugs switched around it's always #3 not firing. Is the gas vent possible for this also, I wouldn't have guessed that. I've guessed coils and replaced with 30 year old ones, mabey that was not a wise move Thanks for any help

Hey all, I am new here and there may be another post about this but I can't find it so if there is another post please send me to it.
I have a 1980 XS 1100 Special I just bought a few months ago. I test drove it and it ran great! I drove it home (the long way of course). After about 50 miles it felt like it may be out of gas the way it bogged down, but all I had to do was pull in the clutch and let it idle down. I let go of the clutch and it came back to life. The next few times I rode it I got a similar occurrence. The more I rode the more it happened and the worse it got but it only happened after a 10 to 20 mile trip. Anything shorter than that and it rode smooth. I took advice and cleaned the carbs (5 times now) replaced the in line filters and petcock filters, cleaned the tank to ensure no more particles could get in the system, and it still does it. Now it actually dies when I pull in the clutch and it back fires real bad. It always starts great but once it rides for about 10 miles it starts doing it. I don't want to spend over $200 on ignition coils and find out it isn't the right fix again.
Any ideas on figuring this one out?

[WMarshy]

I have the same bike doing the exactly same thing. I found that pulling the plug wires off one at a time cyl 1,2 & 4 is noticeable when pulled #3 there is no difference, when checking for spark all 4 have good spark even when plugs switched around it's always #3 not firing. Is the gas vent possible for this also, I wouldn't have guessed that. I've guessed coils and replaced with 30 year old ones, mabey that was not a wise move Thanks for any help

Sounds like the #3 cylinder isnt getting gas to me... have you check the compression in that cylinder? Your issue does not seem like a venting issue as it would affect all the cylinders if it was the tank vent, or it would be #3 and #4 carbs as they share a vent back to the intake box (for 78-79). No bowl vents on the '80+... Swap the #3 plug wire with the #2 plug wire. If the miss follows the wire then you might have a bad plug cap or possibly coil.

[ridinghard]

boncrs

Mine was valves. Had them shimmed and hasn't been a problem since.
Not saying yours is the same thing but it sounds the same.

[DGXSER]

I have the same bike doing the exactly same thing. I found that pulling the plug wires off one at a time cyl 1,2 & 4 is noticeable when pulled #3 there is no difference, when checking for spark all 4 have good spark even when plugs switched around it's always #3 not firing. Is the gas vent possible for this also, I wouldn't have guessed that. I've guessed coils and replaced with 30 year old ones, mabey that was not a wise move Thanks for any help

Typically, if the coils are the problem it will kill two cylinders, not just one. You can try switching the no2, and no 3 plug wires, and repeat your steps of removing wires to see where the miss is at. If it moves to no 2, then it is probably the plug wire or plug cap. If it stays with no 3, try switching plugs with 2 and 3. If it moves its the plug, if it still stays with no 3, its fuel related.