Modern Ignition issues

Vibration used to make my float valves pass fuel at around 4,000rpm.

But if yours wasn’t doing that before, why would it now?

That is interesting. How did you fix it? New float and needle?

Dirtrider said:

Anyways the story is I had a Power Arc system before and never had an issue until my voltage regulator failed and proceeded to fry the ignition, battery and half the bulbs on the bike. Very sad.

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After reading this in your first statement, I would think that if your carburation was good prior to your electrical issue, then why would your meltdown change whether your carbs were set up properly or not? If your bike was truely good before the meltdown, I would bet your issue is related to that meltdown whether it's as simple as a burned up contact in your ignition switch that intermittently works, or an intermittently bad spark plug. I would still think it's electrical if your bike ran well prior to the meltdown.

Check to make sure its not a float needle bowl issue that would also make sense if there is a sympathetic resonance at 4,500 revs

Dirtrider said:

That is interesting. How did you fix it? New float and needle?

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It was worse than interesting, but wasn’t on a Commando so it doesn’t really count.

The problem started when I fitted twin carbs to a T110, on one of those cast alloy splayed adaptors.
After trying flexible mounting, which didn’t completely fix things, I attached the carbs rigidly, as close to the cylinder head as I could get them on the flat type of adaptor pictured above and it’s been ok since then.

o0norton0o said:

I would still think it's electrical if your bike ran well prior to the meltdown.

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I did make a temporary wiring harness that did bypass everything that would have been touched by the high voltage. The only thing electrically I have not tried is to take the stator off and run as a total loss system just to eliminate possible electrical noise coming from the alternator. I still don't know how the different ignition curves would change the intensity of the missfire if it was something like a broken connector or a bad plug.

Hi. Just a thought here. I would check to see that the needle clip has not come off or slipped to a different groove. While in there maybe try dropping the clip to raise the needle one Grove. Also possibly something may be partially obstructing the main/needle jet causing a slightly lean condition. All this may just be coincidence and have nothing to do with the previous failure.

Does it do it if you rev it in neutral? could try to strobe it to see if the ignition is dropping out.

Craig

Here’s one from left field:
Have you checked yr cam chain tension?

Two things, one is that the Raber Parts guys have a lot of technical help pages for the Boyer ignitions and a little hidden detail in those pages is that a faulty regulator which is letting AC onto the battery will cause the Boyer to have erratic timing. My Boyer was doing that so I sent it all the way to Canada for testing and got it back saying it was good. Today I took off my voltage regulator and it shows low resistance across the AC wires. (6 mega ohms instead of 26-30 mega ohms.)

The other thing is that I run a Power Arc as well and I never liked the way the optical disc connects to the cam shaft. I couldn't get it to center exactly. I talked to Power Arc about this and the owner said that it did not matter. Well, you can't tell me that the little optical slits are moving exactly the same speed past the trigger point if the disc is off center. It might not matter as much as I think it does but it bothers me just the same. My solution was to have a bushing made that fits the taper of the cam shaft hole and centers the disc perfectly. To get 10 of them made cost $400 and I have only been able to sell one! I have 8 left, I think, and would take $20 each for them. They have the exact cam shaft taper, are tapped for a puller, are the correct length to put the optical disk where it should go and they fit the little brass bushing that comes with the power arc at the outer end.

The only time my Power Arc miss fired was when I changed from the Boyer and forgot to run resistance plugs along with the resistance wires.

Recently stripped my premiers with old bowls on them, one would always run richer than the other, not matter how I adjusted them. When I had the bowls off I found a brass viton tipped needle and an Aluminium one. I really can't see the need to use a alu one, apparently it is better, but I would suspect the brass one to be more stable in use. The problem is I can't remember which bowl cam of what carb.

Since your original problem was with your voltage regulator, which took out your ignition system and battery, and you've replaced everything... EXECPT the coils it would seem. Further your test harness would not bypass them. I would look there for a vibration induced problem. Coils have a lot of mass internally and very fine wires. Perhaps one is compromised such that it becomes intermittent at specific RPMS due to vibration. The various curves may influence the vibrations and has nothing to do with fuel.

motorson said:

Two things, one is that the Raber Parts guys have a lot of technical help pages for the Boyer ignitions and a little hidden detail in those pages is that a faulty regulator which is letting AC onto the battery will cause the Boyer to have erratic timing. My Boyer was doing that so I sent it all the way to Canada for testing and got it back saying it was good. Today I took off my voltage regulator and it shows low resistance across the AC wires. (6 mega ohms instead of 26-30 mega ohms.)

The other thing is that I run a Power Arc as well and I never liked the way the optical disc connects to the cam shaft. I couldn't get it to center exactly. I talked to Power Arc about this and the owner said that it did not matter. Well, you can't tell me that the little optical slits are moving exactly the same speed past the trigger point if the disc is off center. It might not matter as much as I think it does but it bothers me just the same. My solution was to have a bushing made that fits the taper of the cam shaft hole and centers the disc perfectly. To get 10 of them made cost $400 and I have only been able to sell one! I have 8 left, I think, and would take $20 each for them. They have the exact cam shaft taper, are tapped for a puller, are the correct length to put the optical disk where it should go and they fit the little brass bushing that comes with the power arc at the outer end.

The only time my Power Arc miss fired was when I changed from the Boyer and forgot to run resistance plugs along with the resistance wires.

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Hi ,could you post any picture , as it seems that I had a problem with an Altair pazon , which I partuially(!) solved by fitting a washer between end of cam and EI rotor, due to probably a non standart camshaft not protruding enough thus the rotor was too far from the pick ups, so could be your bushing could help me .........??

This is as good of a photo that I have right now without taking a new one. The bushing goes into the end of the cam and the standard slide puller with a 1/4-28 thread will pull it out.

Hi thank you Motorson, now I could see it will not fit my Altair Pazon........!!

I was actually in my right hand cover just the other day looking for something out of place. Cam chain tension was good. Good thought.

napanorton said:

Since your original problem was with your voltage regulator, which took out your ignition system and battery, and you've replaced everything... EXECPT the coils it would seem. Further your test harness would not bypass them. I would look there for a vibration induced problem. Coils have a lot of mass internally and very fine wires. Perhaps one is compromised such that it becomes intermittent at specific RPMS due to vibration. The various curves may influence the vibrations and has nothing to do with fuel.

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This could be. I will take out the stator, run the bike as a total loss from the battery to both check the stator and possible AC voltage leaking through the rectifier. This way there will be no more questions if its the issue.

74850 said:

Hi. Just a thought here. I would check to see that the needle clip has not come off or slipped to a different groove. While in there maybe try dropping the clip to raise the needle one Grove. Also possibly something may be partially obstructing the main/needle jet causing a slightly lean condition. All this may just be coincidence and have nothing to do with the previous failure.

Does it do it if you rev it in neutral? could try to strobe it to see if the ignition is dropping out.

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I already lowered it once to the center notch and I am not opposed to running it in the bottom groove to try something different. I don't think it moved on me I have seen that happen before so I know what to look for. I also took the carbs off and did the regulation cleaning and checking of the passages and everything is clear. One thing I thought of that is fuel related is I did just switch from running premium fuel to a 91 octane non-ethanol fuel. I don't know if this would cause a miss as it should be better fuel.

It will do it in neutral as well. You can't strobe the power arc because you cannot tell what spark you are picking up. I could do you one better I did put it on the oscilloscope and got a printout of a miss fire where it shows the trigger input failing to fire. I did send this to both Fred and Power Arc and they looked at it and still thought carbs so I am following their lead. I cannot upload to the site to show however so there is that. (Embarrassing as I may be the youngest member...)

Would be curious to see the scope image, you can post a link to Google drive, I think that works.
I too have a power arc , the original one and it seems to work well enough. You said you can see the trigger fail to fire, are you clipped on at the coil? The other thing I would ask is did you set it up with dual fire or single fire. If dual then it is using wasted spark. Is the misfire always on the same cylinder?

Craig

I set this up as a wasted spark system. This was tested on the right hand cylinder only, I never did look at the left with the picoscope....an oversight. The red line is the squarewave trigger hooked on the trigger wire of the coil. The blue line is the spark plug voltage (right cylinder) hooked onto the plug wire.

The reason every other spark event voltage is lower is because this is a wasted spark system and it takes comparably smaller voltage to fire the plug when the compression is so low on the exhaust stroke. The harmonics you can see on the trigger wire are coming through the AC of the laptop because I had left my power-line adapter plugged in...another oversight. This is just a snippet of the 15 seconds I ran the bike.

Wow nice capture on the scope image. Definitely you have an electrical problem on the ignition primary side. You stated that you had run new wires to the unit and isolated the voltage regulator. Did you ground the unit at the piller bolt in the points housing? Did you also ground the cylinder head to the battery? The scope image you attached shows a lack of power supply at almost 400ms then dips below 4v during which should be the firing event. Looks like something is shorting out your trigger. Do you have another battery to test with, even a car battery will work using jumper cables, just make sure you fully isolate the battery in the bike. I am wondering if your new battery has a shorted plate that is affected by vibration (it can happen). If you still have access to the scope I would try scoping the power supply to the coil and also try the other cylinder as well. Did you try a different coil and HT wires?

Craig

The Picoscope program is very handy if you are interested in the file I can send it to you and you can download the free software and look at the whole capture in great detail.




I did not specifically ground the unit with the piller bolts. I wired everything as in the picture above. The kit comes with a whole new feeder #10 direct from the battery so it should have stellar power and ground especially because the coil gets power straight from the battery unswitched. Still like you say the voltage drop is strange. I do not have access the the picoscope my friend is an auto master tech who diagnoses cars with the picoscope so we were using his shop's. He did say that it was weird that the coil voltage was not pulled all the way down to 0v or close and it was weird that it was hovering around 5 when triggered, but that is all I know. I did not intentionally ground the cylinder head to the battery but I did ground the coil only to the cylinder head one time just to see how it would run and it ran exactly the same. I did try a different coil as well but same results, I never did scope it after the coil was changed. I did not change the HT wires. (They did come new with the ignition) I did take them off and inspected the ends looking for arcing and tight connections all were fine. They ohmed out within 15ohms of one another at about 830ohms and didn't change when I moved them all about looking for a poor connection or break.

The battery idea is interesting. I have a spare battery and I will rig it up and see how it goes. The one I am using now is a Shorai lithium battery 14ah, plenty of power to run this bike and I don't know if it is common for lithium batteries to have a random short. I would think it would go into thermal runaway quickly if that was the case and then I would have other problems.

I have run into three different problems with electronic ignitions on a Norton over the last couple of years.
The first was running non-resistor plugs on my Power Arc. It went all kinds of wonky. I put in the proper resistor plugs and it seems back to normal although the data sheet says I voided my warranty at that point.
The second was finding wondering timing on a Boyer. The Raber Parts place in CA that is going out of business has about three sets of PDF instructions on installing Boyers. One of those sheets specifically mentions getting AC on your battery due to a faulty regulator/rectifier. Their instructions say that the symptom will be unstable timing.
And the third was the grounding of the engine itself. With a wasted spark system the spark is going from one plug to the other rather than trying to find ground so I don't know exactly how critical grounding would be in that set up. But in single fire systems the spark is definitely trying to go to ground so good grounding is critical. The commando engine is rubber mounted so a ground has to be through a wire. I use stainless steel mesh wire loom crimped and soldiered to nice copper lugs. I also use stainless steel star lock washers between each layer meaning that one lug would get a washer on each side. I get the ones with the star going to the inside of the washer and the ring out at the outer edge of the washer.