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Turn off lights while starting engine

Markino

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Hi all!
My last Honda (CBR 600RR) has an interesting feature: while I pressed the start button in order to startup the engine... automatically the lights were switched on during the period of starting up. I think this is done in order to not stress the battery douring the startup.
Why on my NC it isn't inplemented? Is it simple to DIY?
What do you think about that?
 
I am not sure it is necessary, as it seems to work find like it is, but it would be a simple relay addition to make it perform as you state. You could use a 5-pin Bosch relay (usually cost about $2 or so). Ground terminal 86, connect terminal 85 to the wire going to the motor starter coil. Break the green ground wire on the headlight and connect one end to terminal 30 and the other to terminal 87a.
 
I don't think it matters a whole lot either way, but I did like how my WR250R did it.

When you first turned the key 'ON', the indicators turned on, but the headlight didn't turn on until you pressed the starter switch and the bike was running. Nice if you're just playing with your GPS or some other switched power source but don't want to start the bike immediately.

trey
 
I am not sure it is necessary, as it seems to work find like it is, but it would be a simple relay addition to make it perform as you state. You could use a 5-pin Bosch relay (usually cost about $2 or so). Ground terminal 86, connect terminal 85 to the wire going to the motor starter coil. Break the green ground wire on the headlight and connect one end to terminal 30 and the other to terminal 87a.

Interesting! But probably for the "best working" the light has to be switched off just before the motor start and switched back on when the start button is relesead.
Using the relay I think the light will be switched off little bit later (relay commuting time) then the starts impulse arrive to the motor....
 
Interesting! But probably for the "best working" the light has to be switched off just before the motor start and switched back on when the start button is relesead.
Using the relay I think the light will be switched off little bit later (relay commuting time) then the starts impulse arrive to the motor....

Both the Bosch relay and the starter solenoid are picked up by the same signal in the circuit that I described. The Bosch relay, having less travel and inertia should close faster, thus the power to the lights will be dropped an instant before the motor starter begins to draw current. Also, the NC contacts are "break before make" which means that the NC contacts open even before the coil is fully engaged. It would probably take an oscilloscope to time the difference between the two signals, but I am convinced that the Bosch will win by a nose. BTW, the light relay coil would only be energized while the starter button is depressed, otherwise, the light ground is maintained through normally closed (held open) contacts.

BTW, if you wanted a more complicated solution (who doesn't, right?) you could use a normally open contact picked up by a relay with a 13 volt zener diode in the (+) side of a coil circuit powered by switched power. That way, the relay would not pull the lights in until a system voltage of 13 volts was achieved, which would only happen after the alternator was spinning (ie: engine running). Sometimes you can find these in packaged form as "voltage sensing relays".
 
I know on my scooter (Honda PCX 125), when the engine is switched off, it recoils into an easier to start position, and the valves are open to allow the engine to spin a bit easier. I wonder if the NC700 engine uses the same technique. As the engine starts almost instantly.
 
I know on my scooter (Honda PCX 125), when the engine is switched off, it recoils into an easier to start position, and the valves are open to allow the engine to spin a bit easier. I wonder if the NC700 engine uses the same technique. As the engine starts almost instantly.

I don't see a de-compression system on the NC700 camshaft assembly.
 
I m going to test out a possibly easier way to do the "engine running" detection. I am going to wire a relay to switched power with the coil grounded through the oil pressure sensor switch. It should hold in the relay until the oil pressure builds, which of course, would mean "engine running". If this works, I may use a normally closed contact on it to control my HID headlight.

ETA: Well, that simple idea didn't work. The oil pressure switch is not a simple ground. It is a resistance grounded feed to the ECM/PCM computer. The oil pressure light "turn on" is a data output from the ECM/PCM to the combination meter. Oh well.
 
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