Electronic Tach

[TripleKing]

I want to install an electronic tach on my 79 Honda CB400T Hawk I as it has no tach from the factory. Since it does not have a tach drive either, I would like to go the electronic route. With cars, I would wire a lead to the ignition coil. However, my bike has two coils. How would I wire it in?

 

[ako]

You are trying to measure the RPM, not the total amount of sparks.

So it doesn't matter if you have a single, a twin or a 4 cylinder, each coil will spark every second crank revolution (4T).

Just connect to one coil.

 

[TripleKing]

OK, a twin will spark twice for every revolution, a four, four times, etc. The tach would need to be adjustable.

 

[ako]

No. You only need to pick up from one cylinder. The tach just needs to be suited to a 4stroke and not a 2 stroke.

Forget about how many pistons there are. The crank is still doing the same speed regardless of piston quantity.