Tachometer in ignition circuit

[krisde83]

Electrics not my strong point whatsoever but I've noticed the speedo is part of the ignition circuit. If this is disconnected will it prevent the bike from starting???

[magg]

Topic heading does not match subject matter but assume you are referring to the speed sensor unit in the speedo that tells the ignition unit when 180km/h has been exceeded, on so equipmed VFR400 models, and then causes a misfire to limit any further speed increase.

[Neosophist]

What bike are you talking about and what do you want to do?

[magg]

Engine will start without speedo sensor connected but engine will misfire above 5000 rpm.

[Neosophist]

Engine will start without speedo sensor connected but engine will misfire above 5000 rpm.

This doesn't apply to NC24

[krisde83]

Sorry lads my post was pretty vague. Yes i was referring to the speed sensor unit in the speedo which i have reconnected and still no spark. I was aware that it tells the ignition unit when 180km/h has been exceeded but wasn't sure if this being disconnected would have any effect on the bike starting.

I have a 1989 NC30 and having problems getting it started. Not receiving a spark at any of the spark plugs. I have carried various different checks as per the haynes manual and recently aquired a high quality multimeter that has the ability to measure peak voltage so going to work my way through the troubleshooting section of the service manual although currently working away from home and wont be home for another 3 weeks.

So far i have done the following: New plugs and leads
all connections and wire continuity within ignition circuit have been checked and all ok (hoping ive not missed any)
ignition coil primary and secondary resistance checked and within tolerance as per haynes
kill switch and ignition switch operating as per design
pulse generator coil resistance checked, one pickup is showing infinite resistance so needs replaced. I have spare that has yet to be fitted.

As there is 2 pickups am i right in saying that one pickup is for the rear coil and the other for the front?? if this is the case then surely i would be getting spark on 2 plugs?? i understand that if there is other issues within the ignition circuit then i wont.

Once i am home i will be replacing the pickups and my next step will be to replace the CDI as i believe these cant be tested?? £70 on ebay for a used working unit. Before i spend the money on a spare CDI i was hoping you could point me in the direction of anything i may have missed or overlooked??

As i have stated previously electrics is not my strong point and this being my first resto project i am learning as i go along and find the forum an excellent source of information. Any info or help you can provide would be greatly appreciated.

[magg]

Although there are two pickups that should indicate separate systems, the circuitry within the ignition module has common associations and thus lose of one pickup may affect all ignition outputs. Your comments suggest that power is available at the coils and ignition unit and there is continuity in the wiring between pickup and ignition unit and coils and ignition unit.

A change to a serviceable pickup may be the solution to the problem.

[krisde83]

Yeah thats correct Magg, there is power at the coils and ignition unit and continuity is good throughout.

Not home for 3 weeks but once home I will change out the pickups and report back.

Thanks very much for your info and reply