T3 cutting out etc

Had quite an issue with the above and rough running, not starting when hot etc.
New points new expensive condenser HMB , Timing spot on new leads plugs etc. Carbs stripped jets cleaned new float needles. New gaskets ( heat transfer ) Bob weights stripped cleaned lubricated. Result ticked over nice ran ok then cut out after 10 miles ? Had to restart rough running. Flash test both cylinders not very far into green? Why? Not as good as my Falcone magneto? Fitted mini coil by battery for left cylinder seems ok far better running 20 mm spark !! Alway assumed a faulty coil would misfire but no ran the cut out can’t start warm? Why would the other cylinder not run? Think both coils suspect. Occurs to me that two coils could be mounted in normal position, two by battery, two complete ignition systems. I like this idea turn a switch as light aircraft new system.
Mainly worked in Ducati’s 70s like design but a few bits piss me off . All or nothing g choke ? Fuel taps anyone know where a screw/ nut type tap can fit a T3 ? Should be able to take tank off in 1 min.
Think thread is 16 mm extra fine ie rocking horse poo. Regards Ratt

I think you’re right focussing on ignition, but you don’t mention valve clearances in your post. Assume you have checked these?


Hi Ian yes have compression 175 right 160 left so good? Since last post discovered why it totally cut out , the ignition switch is faulty although checked this at first low resistance 12.6 volts by fuddling with key a position of low volts no volts could be found!! It’s simple to by pass the whole ignition / stop switch loom direct from battery. With vibration this must have happened. Might be a good start point if anyone has a similar issue. The switch is not the best n 40 years old . Bike runs well but not as smooth as I would like have a huge spark one side n adequate one the other not sure if that makes a difference? Waiting for coils.

Regards Ratt

Most ign faults turn out to be fueling.

I had similar issues with my Le Mans 1000, it turned out to be a broken ignition switch, it was not failing all the time but was intermittent. New switch fitted and the running problems ended. Not obvious until I took the switch apart and the contacts were corroded and worn.