Tach for Buell Blast, reading Half RPM

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andrewleduc88
Tricycle Squid
Tricycle Squid
Posts: 1
Joined: Thu Jul 23, 2020 12:15 pm
Real Name: Andrew
Sex: Male
Years Riding: 16
My Motorcycle: 2007 Buell Blast

Tach for Buell Blast, reading Half RPM

#1 Unread post by andrewleduc88 » Thu Jul 23, 2020 12:42 pm

Hello, I have an aftermarker tachometer for a motorcycle, it's a dual fire tach and the motorcycle ignition coil is single fire, however it is single cylinder. So the tach is reading half RPM, if it idles at 1200 it's reading 600 rpm.

The motorcycle is a 2007 Buell Blast, it has the same engine as a Harley Sportster, except only 1 cylinder instead of a v-twin.
There are instructions for adapting this tach for 2 cylinders, but it doesn't work for one. the adapter is supposed to have two 100k resistors along with 2 diodes going to the negative side of each coil and its supposed to fix the problem, however my problem is it still reads half because it's only 1 cylinder not 2.

Is there anyone familiar with this?
How do I adapt a dual fire tach with a single fire Single cylinder?

I've looked into a frequency multiplier, phase lock loop ... I need a simple circuit to fix this not sure what to use.

I'm wondering what exactly to use?
like which number resistor capacitor diode transitor ect..
I am not sure what the input or output mhz is supposed to be but it obviously is supposed to be between 0 and 8000 rpm. using a 12v signal from the negative side of the coil.

anyone know any about this? I'd really appreciate it.

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