I am stumped

[dbeardslee]

I'll check it but what I have is a clear miss that is felt at the muffler, seen on the tach and on the timing light.

Here's the thing - if it was electrical you'd expect 2 and 3 to be in the same condition. It looks like #2 might not be firing at all, but number 3 looks like it is firing. The only electrical thing I can think of that would only affect one plug is if you had a bad plug wire or cap - but I assume when you changed the coils you changed them wires and all.

Or you're not getting enough gas to #2. That could be because the carb needs attention, or because the valves aren't allowing enough draw to suck it out of the carb.

Seems like you mentioned doing a compression test that showed okay across the board, so that kind of leaves the carbs.

A colortune plug comes in handy for this kind of stuff. You can see pretty quick if you've got spark and no gas, or just a real lean condition. Do you have one?

[dbeardslee]

You might check the vacuum advance line on both ends too. I was diddling with my brothers the other day and managed to get the vacuum line off at the dashpot. If I hadn't looked directly at it when I had the timing cover off I wouldn't even have noticed. JAT

[79XS11F]

I'll check it but what I have is a clear miss that is felt at the muffler, seen on the tach and on the timing light.

[dbeardslee]

When you say "fart" and "sputter" do you mean miss?

I don't know if I'd call it a miss. More like backfiring through the carb and it just makes it run rough. Then again, maybe you could call it a miss.

[79XS11F]

Looking at the plugs I think I'd take a look at #2 for a broken mixture screw tip. And I'd check it through the air jet as outlined in #142 to make sure the pilot circuit is clear. I know when I'm colortuning if I get a carb running too lean it will make it fart and sputter.

When you say "fart" and "sputter" do you mean miss?

[dbeardslee]

Looking at the plugs I think I'd take a look at #2 for a broken mixture screw tip. And I'd check it through the air jet as outlined in #142 to make sure the pilot circuit is clear. I know when I'm colortuning if I get a carb running too lean it will make it fart and sputter.

[79XS11F]

JAT - when you were checking your ignition, did you check the resistance across the high tension wires? Should be 15k ohms ± 15%. Add 10k ohms if you've got resistor caps.

No I didn't but the issue remains even with the Accel coils from my modified bike installed.

Rob

[79XS11F]

Here's what the plugs look like for those with plug reading experience. Looks like #1 and #3 are too rich, #2 is too lean and 4 is acceptable at best. Except #2, they are all what I would call wet.
Before this issue revealed itself, they were all one shade or another of tan.

Rob

[dbeardslee]

JAT - when you were checking your ignition, did you check the resistance across the high tension wires? Should be 15k ohms ± 15%. Add 10k ohms if you've got resistor caps.

[dbeardslee]

I just cleaned the carbs on Betsy after they sat for four years with fuel in them. One thing I noticed during the process - when I sprayed carb cleaner in the air jet hole (jet removed) I got a strong stream coming out of the pilot jet towers on all but one carb. That one just dribbled out. I tried copious amounts of carb cleaner as well as blowing it out with compressed air, and couldn't get the gunk out. I finally used a wired pipe cleaner inserted through the air jet hole, and that cleared the blockage.

I also noticed that there are three tiny little holes under the butterfly, close to the mixture screw hole. You can't see them with the butterfly closed, but you can if you open it. When I sprayed carb cleaner in the air jet hole the other three carbs showed carb cleaner coming out those holes. Wouldn't do it on the problem carb until I used that wired pipe cleaner.

[79XS11F]

Okay, So I switched out the plug leads and the issue STAYED on #1. So this MUST be a carb issue.
I was hopping to not have to pull the carbs but it looks like there's no avoiding it.
Rob

[79XS11F]

So I'm working on this issue again today. Cold compression is good across the board. It idles rough and still misses. I reved her up to 7K she spit out some black smoke then back to normal. She was missing through the entire range but idle was higher when I returned to idle.
All I can conclude now is that the miss is on defiantly on#1. I can see it when I hook up my timing light. I guess I will switch #1 and #4 plugs and see if the issue goes to #4 If it does I will know it's electrical. If it doesn't it must be #1 carb. With all the plugs laid out on the head they were are sparking the same so I am thinking it is a carb issue of some sort.
Rob

[WMarshy]

2 more things you might not have check yet... You'll need a dark night and a spray bottle. Start the bike and let idle. Mist the valve cover area and look for arcs. Do around the coils and any where else like the coil trigger wires that join together in that 2 way female plug. I had that female plug crack and break and had intermittent ignition on one coil. But the main thing is run it in the dark and look for arcing. I spotted that broken plug in the night because it was arcing.

[jetmechmarty]

Some folks replace the battery before it dies and leaves them stranded. (I'm not one of them) 60 months seems long enough for a battery. You need to get this figured out. It will be snowing again soon!

[79XS11F]

Here's something I have not considered as yet. My battery is about 5 years old now. It turns the bike over plenty strong enough and I haven't had any issues with it but I do notice that when at idle the gage lights increase in brightness when the RPMs are increased. It's not a lot but is noticeable. Could my battery condition be at the root of this issue?
Rob