Wiring a tach

[Bear45-70]

You wire the tach into the kill wire (black/yellow). You may have to put a diode in the tach line to prevent the tach from acting like a kill switch.

Black/Yellow is the coil wire

Black/White wire is the kill.

Same signal on them.

[fightingplankton]

the tact my brother bought for his suzuki had him wire it up to the horn wires considering they're only on when the engine is running, made sense to me. then of course you still have to run the other wire to the pulse coil(s)

[TiffanySpree]

Well, I went for a ride. My tach is too happy. 30 mph shows 10k. I'll have to put a resistor maybe to drop it. Not sure. According to my spreadsheet, 30mph should be about 6k (5mph/1k).

[fightingplankton]

is it a dual-fire or single-fire tach?
i understand they make adapters for tachs to connect to the bikes that spark twice per stroke. to my understanding this adapter is just 2 diodes. otherwise it reads double what it should.
so...in your situation, if its reading 10k, probably should be reading 5k

[TiffanySpree]

It's a two stroke twin. So maybe dual fire. But the timing isn't ignition related. It's connected to the lighting coil. So it's expecting half as many pulses as my Elite is outputting. Anybody put their scoot on an oscilloscope to see the pulses? I wonder how many per rev. But I'll check into that rectifier idea. A couple of diodes will rectify one of two pulses.

[fightingplankton]

my brother had a similar problem w/ his tach.
its made for harley's with 2 cylinders...his suzuki only has 1. he bought the adapter for his tach and it works perfectly now. he wont let me take it apart to see exactly how its wired up.

[TiffanySpree]

Ok, I figured it out. I used a small 500 ohm potentiometer. I adjusted it so that I reads 6k at 30mph. After reading the setting with my meter, it is at 240 ohms over 500 ohms or about 48%! Just about where we thought!