Can anyone tell me why a BEC needs a ballast resistor fitted to make sure the engine turns off? Why does it not need it when on the bike? Or am i missing something? From my understanding is even with the engine switched off, theres enough power from the reg/rec to keep the engine running. Why doesnt the regulator/rectifier keep the bike running when switched off at the handlebars on the bike?

N1

Never heard of one being fitted!

I've got a R1 in mine,my m8''s built ZX9/R1/ZX12 BEC's and never had to do anything as you suggest

That doesn't make any sense - as soon as you turn the ignition off, the ECU and coils are disconnected, so there's no spark, so the engine stops. So the reg/rec will only be feeding (for the fraction of a second the stator is still generating AC) the battery and not the main 12V feed.

you talking about the one on an isolator switch as used in motorsport ?, if so, the engine will continue to run if the switch is switched off but the ignition switch is still in the on possition

It all depends how you wire it.

If you use all the original safety circuits and wiring, turning off the power switch will cut the Injectors and ignition which will stop the engine.

If you use an FIA kill switch and turn it off with that you have the risk of the engine not turning off as there is still power coming from the generator. The resistor is wired to send this to 0v in this situation, which stops the engine.

Cheers for the replies folks. It makes sense now.

I think i had confused myself with 'learning on the job' that i am doing.