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kawasaki zx14 motec pdm tyco master relay wiring.

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Hi all

I am making my way through the documentation for the wiring loom for my bike engine car. I am a little confused by the wiring for the starter motor. I have this diagram from the motec webinar on integrating the tyco master relay. the only part I don't understand is it shows positive lead from relay to starter and also a wire from pdm to starter and it is also obviously earthed. I am confused because the starter motor seems to only have 1 wire terminal. can you help please. pics to help. workshop diagram also shows only one input from the starter relay.

https://i.imgur.com/Iyq8vg8.png

The relay is used to provide the battery power to the starter when triggered. The PDM controls when the relay is triggered/energized, so when the starter will spin. The small ground on the relay is for the completion of the relay trigger (so the PDM supplies 12V, and the ground completes the relay trigger). The Starter Motor itself uses the case for ground, and so only has a power lead to be connected.

Thanks David. ok so just to confirm the motec diagram doesn't show a relay in that basic diagram? is there anything missing from that alternator line in the motec drawing? aslo with the starter relay being 30A does that mean I can use 8 AWG wire to the starter or is 6 the smallest option? I can source 8 or 4 AWG tefzel here is australia easily but 6 seems to be a little tricky. I've use 4 awg from battery to master relay to PDM. should I just continue with that? slightly over sized probably for a bike engine?

There is no way the starter relay is 30A. The starter motor would probably draw 100A minimim. We use 6AWG welding wire on our Suzuki 1000cc starters in our bike-powered cars. 4AWG would be perfectly acceptable.

The Motec drawing is showing a standard automotive type starter with integrated solenoid on the side of it. So you feed that a 20A or so power to the solenoid and it activates the bendix (extends the pinon gear), and provides power directly from the battery to the starter. Typical draw on an automotive starter is 150-250 amps.

The alternator wiring is just the output from the alternator. If the Alternator needs excitation voltage (lamp, etc) you would have to wire that in addition. Note the bike engines usually have a generator and a voltage regulator. So you just take the output from the voltage regulator to the battery.

legend thanks