Number One Cylinder Not Firing

[Spiderman11]

The bike has the factory exhaust and I'm not getting any blue smoke. As I said originally, it is extremely cold-blooded but will actually idle amazingly smoothly once it has gotten warmed up........all while the number one pipe is cool enough to be touched by hand. That really blows my mind. Last night I removed the carbs to look for any obvious signs of problems and found nothing that stood out. I actually blew through the fuel supply line just to make sure it wasn't clogged at the carb inlet. While doing this, I operated the float to ensure it would stop the air flow. Like I said, no obvious signs of problems. I will be checking the compression today.

[TopCatGr58]

Hey there Spiderman,

Try moving/swapping the actual spark plug from #1 and 2, not the wire, just the plugs, and see if the cold pipe then occurs in #2, if so, then you know you've got a bad plug. If it's still #1, then could be several things that I think have already been discussed, carbs, plug wires, have you checked your plug caps for their resistance, could have a bad plug cap with way too much resistance....they are usually around 4-8kohms! Just a thought!
T.C.

[Spiderman11]

The plug caps are new NGK's and I've tried the swapping of the actual plugs already. The plug that's currently in #1 started life in the #4 cylinder originally. Hey, I appreciate any and all ideas though. Spiderman is choking on his own web with this mystery.

[pgg]

It does sound like electrics rather than carbs, but a carb slide sticking open while the other 3 are shut MIGHT be the cause?

[pgg]

Also idle the bike at night to spot any stray spark leaks.

[Spiderman11]

Is there any way the coil pickup wires could be causing this problem with the #1 cylinder.......considering I have replaced the plug wires and now am seeing a strong blue spark at the #1 wire?

[s38310]

Are you now riding the bike? If you put a few miles on it and check the plugs it may help. Unfortunately a black or wet plug could be rich mixture or weak spark so you are back to pulling your hair out. I would also warm the bike up and pull each plug wire off one at a time and hold it close to a ground so it has a chance to discharge while observing the tach or listening for a marked decrease in smoothness/RPM. A properly running engine would have a similar drop as each wire is pulled off the plug and replaced. I have had luck by holding a phillips head screwdriver shaft against the engine case with one hand while pulling the wire with insulated pliers and placing it close to the end of the screwdriver. This usually gives you a chance to see, hear, and compare sparks between cylinders.

[Ken Talbot]

Spiderman, I assumed back at the start of this thread that when you said you had read the info on pick-up coil repair that you had actually done it already, not just read it. Time to yank that left side cover off and give those wires a good tug.....

[Spiderman11]

No, I have only done the "new wires in old coils" replacement, not the pick-up wire replacement. I guess I assumed that once I had gotten a steady "flame" from the #1 plug (I've actually had the bike running with the #1 plug out of the cylinder and grounding against the frame) that I had likely eliminated spark as the root cause of my problem. I'll back up and check those pick-up wires now.

To answer a previous post, yes, I've been riding the bike quite a bit, actually. Silly me, I didn't realize that the #1 pipe wasn't getting hot.

[mitch]

WOO HOOO

Are you in for a suprise, wait till you see how much power you have after fixing the pick up wires!! .............MITCH

[Spiderman11]

Did you simply use test probe wires as suggested in the tech tip?

[TopCatGr58]

Hey there Ken and others,

I hate to rain on this parade, but if he's only getting #1 pipe cold, and not the #4 as well, since the pickup coil for each ignition coil controls both plugs at the same time, then that doesn't sound like the pickup coils, otherwise he should have both #1 and #4 pipes being cold!? And he says he's getting a good spark from #1 now, and #4 is warm!?

Sounds more like he needs to try a new plug, then also try swapping the actual wires with #1 and 4, and then if the cold pipe moves to #4, then he knows that there is still something wrong with the #1 wire, plug cap, the new wire fix just isn't exactly right!? Also wondering if an ig. coil could go bad to the point of providing a good spark to only 1 of the 2 leads!?

So...like he said, he inspected the P.U. wires, and they seemed okay before, now if he does the pull test and they crap out, then they may be bad and need repairing, but I don't think this will necessarily fix his "single" cylinder problem!?
T.C.

[Spiderman11]

Topcat, I tend to agree with your line of thinking, but I'm no expert on these things and I'm grateful to everyone who has offered advice. I installed new 7mm Accel wires into my old coils, along with new NGK plug caps. I HAVE done a visual on the pick-up wires, but I realize that doesn't necessarily tell the tale. All four plugs are new and I've swapped them around to see if it changed the situation with the number one pipe and it did not. As I said earlier, I have started the bike while holding the #1 plug against the frame. The result was a seemingly steady blue spark that increased accordingly with engine RPM. I have not swapped the number one and number four wires, simply because of the fact that I know I'm getting the steady spark at number one already.

[Ken Talbot]

You're right there, TC, an intermittent pick-up coil wire _should_ take out two cylinders at once. Imagine how much performance difference that will make.. Spiderman - have you swapped that one plug out yet?

[skids]

I think TC is right about the electrics. Given that you determined that there is spark, if it is not a problem with the plug, I would look into that carb. Float set too high? air jet for the pilot or its passage plugged? Diaphragm sticking the slide/needle in the up position? Synchronize the carbs near idle speed and not at higher rpms? Is the "choke" mechanism working properly with the set screw in the detent? I hope the pilot jet didn't unscrew and fall out! Are you checking all of this with the carbs breather hoses connected to the air box? And finally, a non-electrical, non-carb thing, if the baffle on the left side is shot, one of the two cylinders will give you problems at certain rpms. The cylinder will test ok with a compression test, but EFFECTIVE compression will suffer because of interferring sonic resonance (or whatever you call it).