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It's only one cylinder doing it, it's not your wire/cap combo.

If it does it on the same cylinder with 2 different sets of coils, I'd take a close look at the triggers. I didnt read enough to see whether or not you have points or pickups, but it doesn't matter. If you have points, I'm sure you have set dwell and gap plenty of times, tried new ones, etc. If you have dyna or another ignition with pickups test the A/C voltage while cranking on both pickups.
If there are two trigger coils triggering two ignition coils that each fire two plugs, why would a trigger coil only cause one plug to misfire?
 

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Already discussed. My question is why are you wasting your time asking him to justify his inaccurate info?:D
 

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You could try introducing some propane into the offending cylinder. I find it easier to do this without the airbox on, but you could just drop the filter out and rig a hose so it feeds into the carb in question. A small propane torch setup will do if you can't bum an enrichment kit. You could introduce it through the vacuum port if you have the patience to set up a rig. Assuming you can get the misfire to happen in the garage, start slowly letting propane into the carb or manifold. If the misfire changes dramatically or goes away, you can put money on a fuel problem. Propane has some advantages for this type of troubleshooting, one of which, is it won't cause you to stink. It's also safer than trying to get some sort of combustible liquid up there and being dry, won't soak the plug if you over do it.

If you had a different the of airbox, I would suggest removing it completely, but with the bottom of a CB750 airbox removed, there isn't anywhere on the bike for the heavier than air propane to collect. Even if a person was able to fuck this up, it would be better to die quickly rather than run around the neighbourhood after the engine belched some flaming liquid all over your groin.
 

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Already discussed. My question is why are you wasting your time asking him to justify his inaccurate info?:D
Thats a really good question and I'm not sure I have good answer..... I can say that I haven't read every post, so although I saw the blurb about ignition coils, I didn't see any reference to trigger coils until his post. I admire the fact that Geeto is taking the time and energy to keep up with this thread. It is worthwhile and will help a lot of folks out. Maybe I should just ignore the things people post that I think might be misleading, but I have this thing about "monkey policy". Nobody here knows it all and we can all learn something. Nobody likes being wrong, but as long as you learn from it........
BTW I learned something about rocker spindles in your thread, so thanks for that. Up until recently I had never owned an OIF Triumph.
 

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Thats a really good question and I'm not sure I have good answer..... I can say that I haven't read every post, so although I saw the blurb about ignition coils, I didn't see any reference to trigger coils until his post. I admire the fact that Geeto is taking the time and energy to keep up with this thread. It is worthwhile and will help a lot of folks out. Maybe I should just ignore the things people post that I think might be misleading, but I have this thing about "monkey policy". Nobody here knows it all and we can all learn something. Nobody likes being wrong, but as long as you learn from it........
BTW I learned something about rocker spindles in your thread, so thanks for that. Up until recently I had never owned an OIF Triumph.
Mine is not OIF, it's a 70, last year before they went to OIF. I had mentioned early in his current issue that if it was a coil issue it would show itself on 2 cylinders and not just one, which makes me assume spark plug or spark plug wire. Switching plug wires from the dead cylinder to the other cylinder on that coil will show if that's the issue. I doubt it's fuel related if it works for awhile and then gets no fuel at all on one cylinder.
 

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Agree with Marc. Check out the easy stuff first i.e Plugs, plug caps, and HT leads.
 

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Agree with Marc. Check out the easy stuff first i.e Plugs, plug caps, and HT leads.
I don't disagree with that at all. It's actually why I like using propane. It's a simple easy way to indicate whether its a lean condition or a spark problem. It may not fit into his troubleshooting plans at the moment, but something he can try when and if it becomes appropriate.

Marc... sorry for thinking yours was an OIF. I have friends here that would shoot me for making that mistake.
 

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I don't disagree with that at all. It's actually why I like using propane. It's a simple easy way to indicate whether its a lean condition or a spark problem. It may not fit into his troubleshooting plans at the moment, but something he can try when and if it becomes appropriate.

Marc... sorry for thinking yours was an OIF. I have friends here that would shoot me for making that mistake.
Yup, there is a great divide between loyal pre OIF bikes and post OIF fans. The price drop from pre 71 and post 70 when purchasing a used Triumph is pretty substantial. Even though I'm told the OIF bikes handle better, there's just something about the vintage ones that appeals to me that is lacking with the OIF models.
 

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Discussion Starter #869
Ok so I feel I confused everybody and that's probably because there are several issues going on. Plugs 1 through 4 are showing rich. However only plug 1 has intermittent firing. Here are the things I am doing wrong:
- all plugs are gapped incorrectly
- I am using suppression wires that I made with resistor caps
- I am using plugs I have wire wheeled about a dozen times.

at this moment I am just trying to solve for the problem in plug #1, then I need to figure out why all are showing a rich condition.

Out if curosity i compression checked cyl 1 and 4 and saw 150psi reading in both cylinders. I didn't check 2 or 3 yet but i just don't think the bike has a compression problem.
 

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Ok so I feel I confused everybody and that's probably because there are several issues going on. Plugs 1 through 4 are showing rich. However only plug 1 has intermittent firing. Here are the things I am doing wrong:
- all plugs are gapped incorrectly
- I am using suppression wires that I made with resistor caps
- I am using plugs I have wire wheeled about a dozen times.

at this moment I am just trying to solve for the problem in plug #1, then I need to figure out why all are showing a rich condition.

Out if curosity i compression checked cyl 1 and 4 and saw 150psi reading in both cylinders. I didn't check 2 or 3 yet but i just don't think the bike has a compression problem.
My thoughts are still- if the issue was improper gap, it would not restrict the issue to only plug #1
If the issue was suppression wires with resistor caps, it would not restrict the issue to only plug #1
If you have wire wheeled all 4 plugs, it would not restrict the issue to only plug #1

Your issue is with a fault in one of those items on plug #1, not necessarily the use of the part itself. Star swapping each one of those parts at a time with the corresponding good cylinder and see if the issue follows.

Swap the #1 & #4 plugs and see if the issue moved. If not put them back and swap the wires and see if the issue moved. I think we've narrowed it down to a bad plug or wire. Anything further down the line should affect #1 and #4.
Your rich issue is carburation, and you are correct, fix it after figuring out whats killing the juice to the plug.
 

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As Geeto noted, there are just too many variables which are in question to make any kind of accurate diagnosis at this point. With the paired ignition system however there are some things which can be ruled out. The pickups are out of the equation, since 1 plug on the paired coil is getting spark, so therefore the ignitor/pickup/points are functioning. Power to the coils is not an issue for the same reason. Plug wires and caps are still in the running, because the Honda dual lead coils from this era will, under marginal conditions, pick the path of least resistance and only provide spark to the best lead/path.
My best guess at this point is that it is the plugs in combination with suppressor wires and resistor caps, creating one system which falls below the threshold of old stock Honda dual lead coils.
 

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If there are two trigger coils triggering two ignition coils that each fire two plugs, why would a trigger coil only cause one plug to misfire?
IT DOES HAPPEN! Itll have the energy to fire only one plug at high rpm. Remember, all im suggesting is to test the output. You're already nailing me to a cross
 

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got 4 or 5 hobbyists on this site telling everyone how it is. And youre ALL on this thread where you cant get this bike to run right. tell me how it is again
 

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IT DOES HAPPEN! Itll have the energy to fire only one plug at high rpm. Remember, all im suggesting is to test the output. You're already nailing me to a cross
Its ok to be wrong, as you are in this case. If the trigger coil signals the ignition coil to fire then the trigger is fine. It does not and can not affect the ignition coil other than to give it a signal. You are correct that under a load, a dual output ignition coil may produce voltage at only one of the 2 leads as I explained in a previous post. Hobbiest? BTW you may be getting nailed to a cross, but you climbed up there by yourself and I suspect you have much more in common with JC's companions on the hill than him.
 

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Ok so I feel I confused everybody and that's probably because there are several issues going on. Plugs 1 through 4 are showing rich. However only plug 1 has intermittent firing. Here are the things I am doing wrong:
- all plugs are gapped incorrectly
- I am using suppression wires that I made with resistor caps
- I am using plugs I have wire wheeled about a dozen times.

at this moment I am just trying to solve for the problem in plug #1, then I need to figure out why all are showing a rich condition.

Out if curosity i compression checked cyl 1 and 4 and saw 150psi reading in both cylinders. I didn't check 2 or 3 yet but i just don't think the bike has a compression problem.
There is a possibility that the rich looking plugs are the byproduct of a overall problem with the ignition. As in weak spark shitty fuel burn. Once you replace the plugs, resistance, gap etc, maybe they won't appear as rich next time.

Not sure if this has been mentioned before, but...Just as a general statement, when looking for weak spark in CB ignition systems (after you do the plug, gap. resister thing), don't overlook the kill switch. Normally they work or they don't, but have come across a couple that were bleeding to ground just enough to cause a weak spark. Check it with an ohm meter or just disconnect it to see if things improve.
 

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Discussion Starter #876
There is a possibility that the rich looking plugs are the byproduct of a overall problem with the ignition. As in weak spark shitty fuel burn. Once you replace the plugs, resistance, gap etc, maybe they won't appear as rich next time.

Not sure if this has been mentioned before, but...Just as a general statement, when looking for weak spark in CB ignition systems (after you do the plug, gap. resister thing), don't overlook the kill switch. Normally they work or they don't, but have come across a couple that were bleeding to ground just enough to cause a weak spark. Check it with an ohm meter or just disconnect it to see if things improve.
Kill switch is unlikely because it is brand new. It still may be possible since the replacement is not a Honda part, but so far the item looks well made.

Here is where I am so far: installed new wires this morning. Spark looked brighter on all plugs right away just by visual inspection. #1 cylinder plug didn't look brighter so I swapped it out with a different plug and it got brighter/thicker spark. So either I fouled that plug one too many times or it was a defective plug from the start, either way it looks to be firing with the plug out of the hole at all ranges. However, running it for a few minutes this morning it still wouldn't heat the exhaust pipe and then it occurred to me what pampadori said - I had sediment in the petcock, and I am running without a filter so maybe there is fuel sediment in the slow and main jets as well restricting flow? That's what's on this afternoon's schedule: inspecting and cleaning the jets. Oh and buying a fuel filter because I'm retarded.
 

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If you haven't tried using propane before, now might be a fun time to give it a try and see if that pipe heats up. Easier than pulling the carbs. Question for you.... do you have Scottish ancestry? Maybe we're related. Put a set of new NGK plugs in there.
 

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Discussion Starter #878 (Edited)
If you haven't tried using propane before, now might be a fun time to give it a try and see if that pipe heats up. Easier than pulling the carbs. Question for you.... do you have Scottish ancestry? Maybe we're related. Put a set of new NGK plugs in there.
The pipe has been hot in the past. It's a single wall kerker for a SOHC cb750. It's already take more than a pound of flesh from me touching it while hot in the past.

Part of the point of this thread, in addition to hoisting meself on my own petard to show that even semi-expirenced people can make stupid noob mistakes, was to pinch a penny till abe squeaked. Still I already have bought new plugs but to be honest, if they are just going to fuel foul again, what's the point of putting them in? Let me sort out as many issues as I can and then I will swap the plugs out.
 

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The pipe has been hot in the past. It's a single wall kerker for a SOHC cb750. It's already take more than a pound of flesh from me touching it while hot in the past.

Part of the point of this thread, in addition to hoisting meself on my own petard to show that even semi-expirenced people can make stupid noob mistakes, was to pinch a penny till abe squeaked. Still I already have bought new plugs but to be honest, if they are just going to fuel foul again, what's the point of putting them in? Let me sort out as many issues as I can and then I will swap the plugs out.
I assume the petard you speak of is the english version used to blow castle doors off and not the french version... fart gas.

"IF" the cold pipe is caused by a lean condition, then the propane will make an audible difference. If you are tired of removing skin, no need to touch the pipe. That's only an option if you're into that sort of thing. You will hear that cylinder start to pick up as soon as you turn the propane on. I know I sound like a broken fucking record, but when this works for the first time (no guarantees on this one) you will become a convert. I know I'm a little different, but it I find it still gives me a thrill when it works. You don't necessarily end up with an absolute cause, but it generally points you in the right direction. You must have a propane torch around there somewhere. Turn it on and stuff it in the mouth of that carb. It's made me feel better about pulling carbs off.

I'll go back to my garage now and leave you alone.
 
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