I am wanting to fit a cut off switch to my MK Indy with R1 engine, for sprints and hillclimbs next year, also adds a bit of security and makes it easier to dis the battery when your working on it. Question is do you need the type with the diodes in for a BEC?? You need these in CEC! to stop the engine running on when the switch is activated and also prevents alternator damage but not sure about the BEC. Has anyone fited one to a BEC for racing? Any advice gratefully received
Cheers Paul

if i was you i would just cut of the power to the injectors and to the coils...

thats the way the kill/run/bike angle switch works on my VFR 800 1998

TKs

the answer you looking for is yes or it will run on.


Actually before i get shot down in flames i'm not 100% sure if it would run but i did it that way just in case and all is fine.

[Edited on 10/10/05 by Jon Ison]

Im not sure if it will run on or not either, but it may well fry something because if you disconnect the battery whilst the alternator is still spinning, there's nowhere for the charge to go and it can spike the system the same as it can in a CEC.

You dont need a switch with built in diodes but you do need a switch that has the two supplementary swtches built into it as well as the main battery switch, one thats normally closed, the other normally open.

The way Ive done mine is to use the normally closed supplementary switch to activate the engine stop switch when the key is turned (so in an emergency it will kill the engine anyway), and then the normally open switch kicks in a wire with a big resistor in line (cant remember the value), which then goes to earth from the battery terminal on the engine side. When the switch is thrown this wire effectively earths the positive battery wire from the engine side (so not connected to the battery at this time) through the resistor so any charge from the alternator is dissipated.

Hope this makes sense

I think I get what you're saying Chris, many thanks.
Where would I get the said switch and do you know the name / part for it
Cheers

Paul

Its one of these




This picture is from Vehicle Wiring Products but you can get them from virtually all car wiring / motorsport places like Rally Design, DT etc

Chris

BTW, if I get time I'll draw a diargam tonight so its clearer how Ive wired it up

Cheers Chris, looks like an FIA master switch I know where I can get my hands on one for about £15.00. If you get a chance to do a diagram for me that would be much appreciated

Paul

Yep, AKA FIA master switch

Here's the wiring diagram .....



FIA Keyswitch wiring diagram

Chris

Ta very much

on zzr1100 engine you fry the cdi if you disconect the battery with the engine running! oppppsss big bill