A moment for clarification please

[hannibal]

A rich cylinder runs cooler so that would be my guess. It might be so rich if does not fire at all and is getting hot from adjacent running cylinders. Or it may be running fine for a short period of time, then fouling and failing to fire.

I think a cylinder that never fires would be cold to the touch at start up while a cylinder that runs momentarily would be warm, but cooler than the rest.

[Sandy]

Pulled all 4 screws and they are fine... Right now I need to find out why my #1 cylinder isn't firing while it's getting both gas and spark.....

Just for giggles and a simple, quick diagnostics swap the coil trigger wires and spark plug wires around. The left coil, if wired correctly, should fire 1 & 4 plugs, the right coil 2 & 3. Switch the 1 & 2 plug wires and the 3 and 4 plugs, then swap the coil trigger wire, not the orange wires the other ones. Fire it up and see if the problem moves to cylinder 2 or stays at cylinder 1. If a coil is very borderline it might dry fire a plug and not fire it under load. What the heck, you've tried everything else, it's easy to do and might tell you something .......might not. At least it's one more thing to eliminate as a source of the mystery.

[Uncamitzi]

Spark plug cap.

The caps have just been replaced and I swapped an old one (which was still working) Swapped caps, even swapped out spark plugs. ...

[BigD_83]

Sandy's suggestion of swapping the trigger wires for the coils is a good one.

I had a situation where, even after swapping caps, I would get spark with a plug grounded on the outside the head, but when I put it all back together it wouldn't fire. Baffled me for the longest time. Incidentally, I was working on the bike as it was getting dark, and I noticed I was getting a lightning show along the entire spark plug lead when it was on the plug, in the head. Of course, that was after I shocked the heck out of myself when my bare hand brushed the lead. Replaced the leads and all was right and good again. Swapping the trigger wires (or even just the leads) might point at whether the #1 lead is bad.

[748cc]

Just for giggles and a simple, quick diagnostics swap the coil trigger wires and spark plug wires around. The left coil, if wired correctly, should fire 1 & 4 plugs, the right coil 2 & 3. Switch the 1 & 2 plug wires and the 3 and 4 plugs, then swap the coil trigger wire, not the orange wires the other ones. Fire it up and see if the problem moves to cylinder 2 or stays at cylinder 1. If a coil is very borderline it might dry fire a plug and not fire it under load. What the heck, you've tried everything else, it's easy to do and might tell you something .......might not. At least it's one more thing to eliminate as a source of the mystery.

Shouldn't you swap leads 1 & 4 rather than 1 & 2?? Doing the later would reverse your timing/firing order if I'm following this correctly. Then if 1 heats up & 4 doesn't, you can blame the lead/coil/cap & forgive the plug/carb.

On a side: If you had the air pilot set very lean & the fuel pilot set very rich, would that prematurely foul the plug within say...the first hundred motor revs....to a state where that cylinder would remain flooded and not be able spark until the plug was dried out? And if so, would head temps from the other firing cylinders be enough to ever dry out that soaked plug?? Otherwise you'd probably start leaking fuel down past the valves, diluting your oil to some minor extent, or down the j-tube & into your hot exhaust for 'enhanced surprises'

Thoughts??

[Sandy]

The left coil fires 1 and 4 and fires both at the same time and on both the compression and exhaust stroke, the firing on the exhaust stroke is simply a lost spark. Same goes for for 2 and 3 only 180 degrees a part from 1 and 4. So by switching wires as mentioned you are simply moving the left coil and points or ignition pickups to do the right coils and ignitions job and vica-versa for the right side. If the problem follows the existing #1 wire to #2 cylinder then you know the problem is not valves, compression or carburation but in fact something ignition related, plug wire, bad coils, bad plug, pickups, etc. Sort of eliminates one full segment of operation and narrows the possibilities for diagnostics purposes. If the problem after changing the wires stays on #1 then you know it's not liking ignition related. A quick simple test to keep you from chasing your tail so to speak.

[748cc]

Ahhh, didn't consider the fact that the coils fire at both compression & exhaust strokes. Paint me automotive minded Thanks for clarifying!
Now, about those pilot screw settings...would a spark plug recover from being saturated during a typical ride?

[Steve]

Ahhh, didn't consider the fact that the coils fire at both compression & exhaust strokes. Paint me automotive minded

You had better make that "Old-school automotive minded".
You are thinking of systems that use a single coil and a distributor. With the increase of computers, crank position sensors, etc., many of the cars back in the '90s had a bank of twin-lead coils that fired cylinders that were opposite in the firing order, just like our GSes. I have seen a couple of guys that used those coils on a GS with at least moderate success. In more-recent automotive practice, there is a coil mounted directly to each spark plug.

Now, about those pilot screw settings...would a spark plug recover from being saturated during a typical ride?

It takes a lot less time than that. More like a few dozen revolutions of the engine under load. That short a time will not necessarily give color to the plug, but it will certainly dry out.

.

[748cc]

Ahhhhhh....yeah, old school for sure!! Forgot how I learned that my wife's '06 Dodge had a coil 'pack' rather than just a single coil, and thinking to myself 'That's gotta be expensive to replace if one coil craps out'...it never did thankfully .

Thanks to both Sandy & Steve for setting me straight!!

[Steve]

We just present facts. The number of curves you take is up to you.

.

[Tangent]

It's seems fairly obvious to me that the carb's inlet is at the rear, ie connected to the airbox - because that's where the air is drawn In to the carb. And passes Out of the carb through the Outlet, into the engine.

It seems to me that the confusion may arise because when people are talking about the 'inlet' side, they are, in fact, talking about the inlet side of the engine, rather than the inlet side of the carb itself - ie "carbs are on the inlet side of the engine, therefore the bit of the carb that connects with the engine is the inlet".

If you look at the carb in isolation, there's only one place where the air come In, and another where the air goes Out.

And once it goes Out of the carb, it does go into the Inlet tracts and valves of the engine - but they are not part of the carb......