Ignition, general question
Posted: Mon Feb 01, 2021 9:50 am
Hello everyone, and as it's my first post in 2021, Happy New Year.
I'm working on a bike, not my CBX, it's actually a Honda V4 and I have a question if anyone can help please. The spark seems very weak, if I take a plug from this bike and pop it in my FTR223 I get a great big fat spark so I know the plugs are OK. I was pondering the ignition wiring on the bike and to prove to myself I thought knew what I was doing I gabbed a spare coil from a box of bits to see if I could bench test a Honda coil.
The spare coil is off a VF750F and is the typical two low tension spade terminals and two HT leads. This coil tests OK to the Honda specification in the maintenance manual, 2.8ohms primary between the spade terminals, 22kohms between the plug caps
I wired the test rig up on the bench as follows:
First spade terminal to a battery positive
Second spade terminal to a flying lead
Plugs fitted to the HT caps and then the plug threads joined together to simulate being screwed into a head, (the current flow on this system is through the first HT lead to the plug, plug to head, head to plug, second HT lead back to coil).
When I placed the flying lead on the battery negative and then removed it I expected to see both plugs spark as the magnetic field induced in the primary winding collapsed but nothing. Reversing the polarity on the primary didn't help. If it was an old bike with contact breakers the test I'm doing would seem representative, I can't see why it would be different with the coils from an electronic ignition system, when all's said and done isn't a coil just a transformer?
So my knowledge and understanding is lacking. Maybe just dabbing a wire against a battery terminal is flawed?
Forgetting the troublesome bike for the moment, can anyone explain why the bench test didn't work as I expected it to?
Thank you in advance,
Chris.
I'm working on a bike, not my CBX, it's actually a Honda V4 and I have a question if anyone can help please. The spark seems very weak, if I take a plug from this bike and pop it in my FTR223 I get a great big fat spark so I know the plugs are OK. I was pondering the ignition wiring on the bike and to prove to myself I thought knew what I was doing I gabbed a spare coil from a box of bits to see if I could bench test a Honda coil.
The spare coil is off a VF750F and is the typical two low tension spade terminals and two HT leads. This coil tests OK to the Honda specification in the maintenance manual, 2.8ohms primary between the spade terminals, 22kohms between the plug caps
I wired the test rig up on the bench as follows:
First spade terminal to a battery positive
Second spade terminal to a flying lead
Plugs fitted to the HT caps and then the plug threads joined together to simulate being screwed into a head, (the current flow on this system is through the first HT lead to the plug, plug to head, head to plug, second HT lead back to coil).
When I placed the flying lead on the battery negative and then removed it I expected to see both plugs spark as the magnetic field induced in the primary winding collapsed but nothing. Reversing the polarity on the primary didn't help. If it was an old bike with contact breakers the test I'm doing would seem representative, I can't see why it would be different with the coils from an electronic ignition system, when all's said and done isn't a coil just a transformer?
So my knowledge and understanding is lacking. Maybe just dabbing a wire against a battery terminal is flawed?
Forgetting the troublesome bike for the moment, can anyone explain why the bench test didn't work as I expected it to?
Thank you in advance,
Chris.