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crank and cam trigger timing


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I have a 180degree 4-stroke twin. The crank trigger disc has 6 evenly spaced teeth as suggested by Link. The cam trigger has a single tooth. I'm just setting it up and want to know the ideal position for the camshaft trigger in crankshaft degrees before or after TDC ignition  for #1. Also is it measured to the leading edge of the tooth, trailing edge, or centred?

The crankshaft trigger disc is mounted on the original alternator rotor hub. With 6 teeth and 6 mounting bolts and being keyed to the crankshaft it effectively is non-adjustable. Without precisely measuring the angle from the sensor the tooth approaching the sensor is about 20-30 crankshaft degrees away at #1 TDC.

#2 fires 180 crankshaft degrees after #1.

Using an Atom G4+ if it makes any difference.


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You can adjust the trigger in software through 720°, so it does not really matter about where you put it in relation to the crank sensor, the cam sensor just tells the ECU where the crank sensor is within the 720 degree cycle.

So your first 3 teeth are around 30, 90, 150°'s.

You should make sure the tooth is centralised between two of the 6 crank teeth, I would simply place it dead centre of two cam teeth at 90° and 150°................... so 120°  crank.

This keeps the trigger away from each other and also puts any sync events outside of normal ignition events.

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