Motorcycle Forum banner

How to hook up a portable tach?

12K views 4 replies 2 participants last post by  Stalker7d7 
#1 ·
Anybody know how to hook these things up?

I got my hands on an old one that is for 6 and 8 cylander engines(says just to multiply the reading from 8 cylinder setting by 2 to get 4 cylinder rpm), with tach, dwell, and pt. res... It's got a black wire, and a red wire, both with small alligator clamps on the ends..

I swear I've searched everywhere for instructions on how to hook these up(using wrong words/terminology?), and can't find it..
 
#2 ·
You connect the black wire to a good ground; the engine fins will do. The other end connects to the wire from the points to the coil, usually at the coil. The other side of the coil is battery power, and you'll get no signal.
 
#4 ·
You can hook it up to either coil, the only issue is whether yours is a single-fire or dual-fire bike, that is, do both coils fire on every revolution, or only one? Firing only one per revolution is usually only on fuel-injected bikes, because the control system already knows which cycle the cylinder is on. Or, on bikes with points driven by the camshaft, like my old CB450.
If it fires on every revolution, the tach reading, when set to 8, will be multiplied by 4; otherwise, by 8.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top