750 Commando misfire on acceleration.

Schwany said:

TriSpark is really fond of a dedicated ground from the battery. Just hooking up the Red wire is not as good as adding a dedicated ground wire all the way from the battery to the pillar post your TriSpark Red wire is connected to.

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I disagree. IMHO, Tri-Spark is very fond of a proper ground to the engine. Grounding the unit as designed is fine if the engine ground it good. The standard location of the ground wires to the head steady plate can leave the engine not perfectly grounded. I prefer connecting those ground wires directly to the head or adding a ground directly to the head. Providing a ground from the Tri-Spark directly to the battery is only masking the actual issue and since the engine ground is how the high voltage travels to ground it's a bad idea to provide a secondary path.

IMHO you cannot have too many grounds.

Thank you all for your input. Decided to go back to dual amal carbs and try that out. Will post how that works out.

Update. Seems all the issues were related to electronic noise. Installed a filter on my podtronics. With a tri spark apparently thats required. Wish I had found out sooner. But then again, I learned a lot in the process. Thanks to all for your help.

Mike750 said:

Update. Seems all the issues were related to electronic noise. Installed a filter on my podtronics. With a tri spark apparently thats required. Wish I had found out sooner. But then again, I learned a lot in the process. Thanks to all for your help.

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Plus....I took the red wire from the tri spark right to the postive terminal on coil.https://granttiller.com/lets-talk-about-tri-spark

Mike750 said:

Plus....I took the red wire from the tri spark right to the postive terminal on coil.https://granttiller.com/lets-talk-about-tri-spark

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The latest in urban legends Grant does not say to route it to the coil - he says to the battery. I like, respect and agree with Grant on almost everything - but on this I respected the owner of Tri-Spark and the designer of their electronics ignitions, Stephen Kelly.

You won't hurt and anything as long as the engine is fully grounded and that terminal of the coil is fully grounded. If it loses ground, or if the coil shorts, the Tri-Spark output transistor will burn up in less than one millisecond. If wired by the book and if either happens the bike won't run but you won't have to buy a replacement.

Pease re-read my post #21.

BTW, I've sold hundreds of them and installed many. Two returns on units for twins - both are running fine in bikes now - in other words, nothing wrong with them. Not including the first model (no test button) Stephen has had a few returns, most had nothing wrong but last I checked with him almost all that did have a failure had burned output transistors.

marshg246 said:

The latest in urban legends Grant does not say to route it to the coil - he says to the battery. I like, respect and agree with Grant on almost everything - but on this I respected the owner of Tri-Spark and the designer of their electronics ignitions, Stephen Kelly.

You won't hurt and anything as long as the engine is fully grounded and that terminal of the coil is fully grounded. If it loses ground, or if the coil shorts, the Tri-Spark output transistor will burn up in less than one millisecond. If wired by the book and if either happens the bike won't run but you won't have to buy a replacement.

Pease re-read my post #21.

BTW, I've sold hundreds of them and installed many. Two returns on units for twins - both are running fine in bikes now - in other words, nothing wrong with them. Not including the first model (no test button) Stephen has had a few returns, most had nothing wrong but last I checked with him almost all that did have a failure had burned output transistors.

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All I know is when I installed the tri spark filter and wired the way Grant said , all was glorious. Lol. That being said, I guess I should have just done the filter first without re wiring the tri spark.

Grant does say to wire to the coil. With a good ground on the engine side of the head steady.

marshg246 said:

I disagree. IMHO, Tri-Spark is very fond of a proper ground to the engine. Grounding the unit as designed is fine if the engine ground it good. The standard location of the ground wires to the head steady plate can leave the engine not perfectly grounded. I prefer connecting those ground wires directly to the head or adding a ground directly to the head. Providing a ground from the Tri-Spark directly to the battery is only masking the actual issue and since the engine ground is how the high voltage travels to ground it's a bad idea to provide a secondary path.

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No problems whatsoever wiring a ground directly to the TriSpark on my Norton. My coil is also grounded to the battery via a junction block. My entire frame and engine are grounded to the battery. In my case no isoelastic rubber, or wiring connected to the head steady. Makes no difference, my suggestion would work on a Commando. I don't expect anyone to do it though. Radical thinking round here. lol

Anywho, I had a misfire the other day and it turned out to be the ignition wire to the coil snapped off where the wire insulation ended at the connector on the dual coil. It was a total dead engine misfire on a motor with about 80 miles on it. Thought the sky was falling. Pulled into a parking lot coasting on a dead motor bike, took a look around the bike, fixed it, and off I went.

Further insanity: The two wires that go to the TriSpark are twisted around each other the full length. I'd take a pic of it, but they are inside wire wrap. That twisted pair thing is a hangover from the previous Boyer ignition. I'm not so sure the TriSpark appreciates it, but I did not change it and it runs.

Gimme some of that "That's all Wrong juice." I live for it.

Schwany said:

Further insanity: The two wires that go to the TriSpark are twisted around each other the full length. I'd take a pic of it, but they are inside wire wrap. That twisted pair thing is a hangover from the previous Boyer ignition. I'm not so sure the TriSpark appreciates it, but I did not change it and it runs.

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That is insane and did not come that way from Tri-Spark. Their wires are about 3" long. A twisted pair is not proper for power lines which is what the Black/White a Black/Yellow are.

With no isos and a grounded frame your engine should be well grounded, but this is a Commando thread in a Commando forum and Commando frames are not a part of the ground system unless you consider the headlight shell, to fork ears, to triple tree, to handlebars, to clutch mechanism to clutch cable to gearbox to cradle to engine to be a good ground

marshg246 said:

That is insane and did not come that way from Tri-Spark. Their wires are about 3" long. A twisted pair is not proper for power lines which is what the Black/White a Black/Yellow are.

With no isos and a grounded frame your engine should be well grounded, but this is a Commando thread in a Commando forum and Commando frames are not a part of the ground system unless you consider the headlight shell, to fork ears, to triple tree, to handlebars, to clutch mechanism to clutch cable to gearbox to cradle to engine to be a good ground

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I thought I was going to have to go a day without my dose of condescending expert commentary. Whew, thanks. I feel better already.

The twisted pair that was already in place and I am running to the TriSpark ignition hasn't made any difference. I figured one of those wires powered the intelligence and magnet sense circuitry in the stator and the other fired the coil when triggered. Might be able to cause a misfire if they shorted together, but hasn't in a year, and they have been on the bike for over 30 years.

I did not get 3 feet of wire in the TriSpark ignition I bought from you. The TriSpark MOSFET reg/rec came with 3 feet of wire, but not the TriSpark ignition. There weren't any other wires in the box other than the 3 short wires out of the stator plate. The Red ground, and the black/white black/yellow. The twisted pair I am referring to for the ignition was already in place before I bought the TriSpark ignition, so I used it. I'm not recommending anyone else ever do it. I'm just mentioning I did it, and it is not a problem.

For the record, I don't give a hoot what forum it is. Nortons are Nortons, engines are engines, ignition is ignition. A dedicated ground from the battery to the points housing works better than any of those sources mentioned. It doesn't mask a thing. It's just a good idea for ignition. Not disagreeing with anybody.

If it is not an electrical problem, the miss is probably caused by too lean on the needles. If you raise them one notch bt lowering the clips, the miss should disappear if it is a jetting problem. Too rich will not usually cause a miss, unless it is extreme.
If your motor runs well at low throttle openings, and the the miss appears as you accelerate, the needles are probably one notch too low. That is the way I tune my carbs. I lower the needles unti I get the miss, then I raise them one.
When you ride your bike you should never get a miss, and if you do, you need to fix it immediately before you start burning pistons. Check all the electrical connections.

marshg246 said:

That is insane and did not come that way from Tri-Spark. Their wires are about 3" long. A twisted pair is not proper for power lines which is what the Black/White a Black/Yellow are.

With no isos and a grounded frame your engine should be well grounded, but this is a Commando thread in a Commando forum and Commando frames are not a part of the ground system unless you consider the headlight shell, to fork ears, to triple tree, to handlebars, to clutch mechanism to clutch cable to gearbox to cradle to engine to be a good ground

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I would fit an earthing strap, between the engine plates ant the frame. I would not rely on stuff which is jiggling around.

Everything on a classic Norton is jiggling around, iso or not. Hence, nothing on a Norton is something to rely on.

marshg246 said:

That is insane and did not come that way from Tri-Spark. Their wires are about 3" long. A twisted pair is not proper for power lines which is what the Black/White a Black/Yellow are.

With no isos and a grounded frame your engine should be well grounded, but this is a Commando thread in a Commando forum and Commando frames are not a part of the ground system unless you consider the headlight shell, to fork ears, to triple tree, to handlebars, to clutch mechanism to clutch cable to gearbox to cradle to engine to be a good ground

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That is good sound input Greg, especially pointing out the relevance of a solid mount vs iso mount has to the topic of this thread.

Ended up being noise from my new podtronics interfering with the tri spark. Fixed with filter supplied from tri spark. All is good now.