dcarver
Well-known member
Ok, ok you forced my hand. I'm posting about bench testing ignition coils from a 1979 KZ1300 not an FJR. But both platforms use a 'wasted spark' ignition system so commonality exists.
Installed new YellowSquare ignition coils. Bike still didn't run good.
Ground plugs to valve cover, crank engine, hmm, maybe I kinda sorta spark but not like WOW, look at THAT!
Time to bench test the coils.
Search Google. Find this. Ez pz.
Batt + to coil +
Coil neg to switch to batt neg
Ground spark plug(s) shank to Batt neg
Connect both spark plugs shank together (wasted spark systems require this connection)
Hi tension leads to sparkplug caps
Close then Open switch, primary field collapses, induces hi voltage in secondary, discharges through plug.
But. It doesn't work. No spark.
WTFO? Not likely all coils are bad. Must be test set up.
Check all wires for continuity
Check plug resistance
Check switch
Everything checked out SAT
Got to thinking. Auto ignition coils use a condenser to prevent premature point pitting - due to high voltage induced into points. The condenser blocks that voltage.
Installed a condenser and voila, spark.
Question 1
What I don't know is why adding the condenser enables plugs to spark. Could it be the switch, as it opens the primary to induce field collapse and 2ndry discharge is discharging though the switch contact?
Don't find answer about condenser. But in doing research, find *one* reference that weak / no spark can be result of coil primary over saturation. The KZ has 8000 rpm redline. 8000/60 means a spark event (build up primary EMF, open circuit collapse field, induce secondary, discharge spark) has to occur every 7.5 milliSeconds. That's FAST!
A typical spark duration is ~1.3 milliSeconds. Sooo, the primary has to establish full field in 7.5 mS minus the 1.2mS for spark duration which equals 6.3 mS.
Obviously, I can't toggle the switch that breaks the primary negative side faster than about once per second. Meaning the primary flux is over saturated.
Question 2
What I don't know (a LOT
) is how severe the high voltage degradation is given an over saturated primary?
Research revealed this beauty, a Hall effect pulse width modulator that can test devices requiring a pulse - stepper motors, fuel injectors AND ignition coils. It's coming from <gasp> China on a slow boat.
https://www.amazon.com/dp/B0CZ84R1JC?ps ... ct_details
[youtube][/youtube]
Hoping someone a whole lot 'fart smeller' than me can chime in with facts, ideas, thoughts.
I know, it's a technical rant. But it's real to me!
For the complete diatribe...
https://candybuttorg.ipage.com/cba/node/1430
Installed new YellowSquare ignition coils. Bike still didn't run good.
Ground plugs to valve cover, crank engine, hmm, maybe I kinda sorta spark but not like WOW, look at THAT!
Time to bench test the coils.
Search Google. Find this. Ez pz.
Batt + to coil +
Coil neg to switch to batt neg
Ground spark plug(s) shank to Batt neg
Connect both spark plugs shank together (wasted spark systems require this connection)
Hi tension leads to sparkplug caps
Close then Open switch, primary field collapses, induces hi voltage in secondary, discharges through plug.
But. It doesn't work. No spark.
WTFO? Not likely all coils are bad. Must be test set up.
Check all wires for continuity
Check plug resistance
Check switch
Everything checked out SAT
Got to thinking. Auto ignition coils use a condenser to prevent premature point pitting - due to high voltage induced into points. The condenser blocks that voltage.
Installed a condenser and voila, spark.
Question 1
What I don't know is why adding the condenser enables plugs to spark. Could it be the switch, as it opens the primary to induce field collapse and 2ndry discharge is discharging though the switch contact?
Don't find answer about condenser. But in doing research, find *one* reference that weak / no spark can be result of coil primary over saturation. The KZ has 8000 rpm redline. 8000/60 means a spark event (build up primary EMF, open circuit collapse field, induce secondary, discharge spark) has to occur every 7.5 milliSeconds. That's FAST!
A typical spark duration is ~1.3 milliSeconds. Sooo, the primary has to establish full field in 7.5 mS minus the 1.2mS for spark duration which equals 6.3 mS.
Obviously, I can't toggle the switch that breaks the primary negative side faster than about once per second. Meaning the primary flux is over saturated.
Question 2
What I don't know (a LOT
Research revealed this beauty, a Hall effect pulse width modulator that can test devices requiring a pulse - stepper motors, fuel injectors AND ignition coils. It's coming from <gasp> China on a slow boat.
https://www.amazon.com/dp/B0CZ84R1JC?ps ... ct_details
[youtube][/youtube]
Hoping someone a whole lot 'fart smeller' than me can chime in with facts, ideas, thoughts.
I know, it's a technical rant. But it's real to me!
For the complete diatribe...
https://candybuttorg.ipage.com/cba/node/1430
