It's old, 4 cylinder, 12v, a fiver on ebay and it works, but steadfastly reads half the revs. There's a trimmer inside but it's for fine adjustment. Any ideas?
is there any form of resistance multipliers in the unit, on some of our A to D cards at work, we can change the amplifier gain resistance to x2, x10 etc etc - it sounds like you could do with a x2 increase
What's it off of? Most 4 Cylinder bikes work on a wasted spark, I know some car ignitions do the same thing. Rather than take the pulse from the terminal on the coil, try coiling a piece of wire around HT lead one, four times should do it, plug end towards distributor then coil the same piece of wire around HT lead two in the same way, connect the pick up to this. Seriously!it works!
dklawson@mindspring.com email this guy...assuming he's still at the same address Electronic Tachs have a potentiometer inside to calibrate the signal received, so if it's registering exactly half (as verified by a known good Tach) then I reckon it's what the others have suggested. maybe you measure the resistance of the potentiometer and fit another with half the value...if it f*cks up, I'll buy you a beer next time I see you
