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Anybody know the output spark energy of "Coil on Plug"s?


Pursuvant

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I'm questioning if the factory Coil on Plug (COPS) systems make enough spark energy across the rpm spectrum on modern Japanese bikes. How good is COPs?

In  late '70s early '80s we learned to toss the UJM factory coils in trash and replace with Andrews 30K volt performance coils. Factory coils could be as low as 8K volts in the olden tymes.

If the factory COPs are not making 12K volts and up (with the rpm) I would be watching for a reasonably priced aftermarket COPs to show up. Found a couple of hi-performance sources now but wow, prices are out of sight, $500 and up, way up. Andrews were about $59, you couldn't afford not to do it, because it smoothed out inconsistencies in slide carb fuel metering.

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I don't understand the need for aftermarket higher volt coils. Please educate me. 🤔

Unless you're experiencing weak spark with OEMs that leads to unburnt fuel , what is gained by higher voltage coils?

DewMan
 
Just shut up and ride.

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"it smoothed out inconsistencies in slide carb fuel metering"

Respectfully, we were taught both lean and rich inconsistencies benefited from a substantial increase in spark energy.

Fueling was hard to get right after pipe & air filters added with slide carbs. We had to try different main jet (full throttle), then the harder part finding a good needle jet (low+mid-range) to try to do what is so easily done by a fuel map and fuel injection today. You never got it perfect across all rpms. You could do a plug check at 8K rpm, nice brown plug burn, but at 4K it could be rich or lean. Adjust one place throws off the other rpm fuelings. We knew how to read plugs, and we did the best we could.

Does your bike idle consistently? I would expect if you did nothing else but add a 30K volt COP right now you would see your idle smooth (and it would increase the idle rpm on slide carb bikes), even though the real problem of rough idle is you need a flash fueling adjustment. The spark energy has an impact, rich or lean. You would be vary much aware that you had made a positive change to your FZ/MT across a wide band of rpm.

More complete combustion of the same quantity of air/gas mixture, courtesy of spark energy.

Edited by Pursuvant
Clarify cause of inconsistent idle is fueling map
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Thank God for fuel injection and digital ignition is all I have to say.

Modern technology has made plug chops, jetting and carb fettling unnecessary if not impossible. I too used automotive coils 'back then' but those were the days of points and condensers, mechanical advance, dwell and two stroke timing, may they stay at rest in peace.

These coil on plug doohickeys have way more than enough juice for their jobs. That's what I know. 

😀

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9 minutes ago, mossrider said:

These coil on plug doohickeys have way more than enough juice for their jobs.

Thanks Moss, so let's see if there is somebody who has measured them, because it's interesting if nothing else

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You can estimate the output voltage of an ignition coil by the distance the spark is able to jump to ground.
There are even small simple devices to test this spark gap, plugged in instead of a spark plug.
I've modified several vintage bikes from old mechanical ignition to modern full electronic ignition and with this, even a small 2stroke produces more than 10kV (~ 10mm long spark, 1kV per mm spark gap), powered by an permanent magnetic alternator/stator generator while kickstarting. Here I am testing one of my modified bikes for success, you should be able to test the FZ-07 the same way. But better no touchy touchy with the fingers ;)  :

 

Of course there a better ways to do this with special equipment, but HV impulses are sometimes a tricky thing.

 

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26 minutes ago, Pursuvant said:

Thanks Moss, so let's see if there is somebody who has measured them, because it's interesting if nothing else

I was actually about to do just that but decided to put them back on the work bench and walk away. I had the jump pack out to energize them and the voltmeter and then I envisioned everything in my life that had gone wrong up till now.

I've tested many between 15,000 and  40,000 volts in the recent past. I'm just going with that. Lol.

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