Coil and TCI question

[trbig]

Writing out lengthy posts is a pain on my little HTC Touch Pro.

You mean you don't have voice recognition where you can just have it type as you talk? How will you ever show your face at the next Star Trek convention?

Tod

[Ivan]

I do, but it doesn't understand my drunkeneese accent.

[tw1980]

Ivan I was able to spend some time researching last night.It looks to me like the coils you talked about should work if they are not off of a car with cdi.If they are cdi coils they will probably damage the ignition unit in time.If you're an automotive tech you probably already knew that.I stumbled across some interesting stuff on Yamaha tci units (sorry I was referring to them as tdi units in earlier posts)and repairing them.I you're interested let me know and I'll post a link.I hope this works my coils are looking sad as well. Terry

[randy]

I wasn't aware that cars ever came with CDI's.?

[tw1980]

I think so Randy,it looks to me like Bosch Motronic,Ford TFI,and GM HEI,to name a few are all CDI type ignitions.It looks to me like like the cdi type ignition has more control ability than tci and is better suited for computer controlled ignitions.I hope I'm not leading anyone astray here I only design and repair consumer electronics and don't have much experience with ignition systems.If I'm wrong maybe one of the automotive electrical guys can help me out. Thanks Terry

[oldyam80sg]

I did do the new wires in the old coil mod when i had problems years ago,beside i like the molded in spark plug boot.Got tired of sniping bad wire.

[Ivan]

CDI is the primary control circuit. It matters not to the coil how it is fired. If the coil has a primary circuit resistance that is acceptable to the control circuit, all should be good. A coil is basically a step up transformer. No matter what you use to control it, it does the same thing. CDI just puts a lot more juice through for a much shorter time than a TCI or breaker type ignition.

The "charge" time on a coil only involves the time it takes to saturate the magnetic field of the primary circuit. This never does stop using electricity like a battery or a condenser would. The energy is being used to generate a magnetic field, not ot store energy. Therefore the onrush current is relatively small and does not have the time or amplitude to affect the ignition module. IIRC it is only about 2-4 milliseconds before the coil stabilizes and merely microamps difference in current. The "high" portion of the primary cycle is very flat. When the voltage drops, then the current goes wacko with coil oscillations and feedback and such. That is where the condenser comes into play to keep points from frying and electronic circuitry from giving up the magic smoke. The thought that any coil with the same resistance would flow a different amount of current in a stable voltage environment violates ohms law. I.E., the voltage is regulated to about 14.5V so we can call it a constant. If the primary circuit resistance is the same between two coils, then via V=IR the current would have to be the same.

The only difference between modern coils in cars with waste spark ignition systems and our bikes is that a lot of times two coils are put in the same package, with four outputs. They are also much smaller and the primary windings are made with finer wire and the core is smaller which shouldn't affect it much since transformers work on ratios of windings.

[tw1980]

Very good explanation Ivan and you are correct.It's me who failed the explain my concern.I guess that's why I'm not a professor and have summers off.By the way you can't be arrested for violating ohms law.If you have an analog multimeter you might measure the primary current before and after,and if you"re an automotive tech do you have a way of measuring the output of the secondary? This could be a cheap alternative for higher performance coils.If the switching transistors in the tci fail we can probably replace them.Even with higher current versions and with a higher piv if necessary.Good luck and I hope your idea works. Terry