rev counter not working

[otto]

as above i have bought a track bike which appears to have a few problems which i am working thru it came with a small 2"rev counter which i dislike so i have bought a good used tested 30 tacho off gfracing ihave a good live feed and good earth to it and continuity in the cable from the cdi to the connection block on the tacho (tested from the solder on the back of the pcb in the cdi) but no tacho, is it possible to connect anywhereelse or can i test output of the signal wire at all 1st trackday this friday would like to have a tacho

[Drunkn Munky]

What bike you fitting it too, 30 or 35?

[otto]

sorry its a30

[Drunkn Munky]

Theres a possibility that it could be a 35 tacho which wont work with 30 electrics and vice versa

[otto]

its from gf racing marked as 30 i also have one which came in spares box with bike same thing so im thinking cdi can i get round this or is it new cdi or aftermarket tacho is there a way to test signal wire

[Drunkn Munky]

Was the old 2" tacho working? and how was that connected?

[otto]

sorry for delay been in garage old one wired off coils works fine but is just too small

[Drunkn Munky]

Could well be the cdi then if your sure all conections are good

[otto]

ok thanks for help do you know if its poss to test signal wire output or anybody know

[magg]

Failed tacho output from ignition unit has happened to others, might be why a tacho driven by the ignition coil output was fitted. Testing the ignition unit tacho output is tricky without suitable test equipment, usually easier to substitute a known good one.