BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: aso215kd on 22 Mar, 2024, 20:02

Title: Warm Starts
Post by: aso215kd on 22 Mar, 2024, 20:02
Having difficulty with warm starts.  I can hear it try to light off on the first warm kick but after that it doesn't even try to light off.  I followed the Owner's Instruction Manual, extra tickle, half choke, but rarely will it come to life.  After about 40-50 minutes, it works.  Make for a long fuel stop.  Any suggestions?
Title: Re: Warm Starts
Post by: JulianS on 22 Mar, 2024, 20:26
You dont say which bike?

If magneto ignition the condenser may be failing when hot, cools down it starts OK and works until you try the next hot start.
Title: Re: Warm Starts
Post by: aso215kd on 22 Mar, 2024, 20:50
Oops, yer right I didn't identify the model.  '64 A-65 with an Amal knock off concentric carb and electronic ignition.
Title: Re: Warm Starts
Post by: LightningAndStarfire on 22 Mar, 2024, 23:47
Ignition coils or your electronic ignition could be defective. Vapour lock in the carb is less likely.

Do you have 6 volt coils in series? 12 volt coils work but give weaker sparks. Battery should be ok.
Title: Re: Warm Starts
Post by: rhyatt on 23 Mar, 2024, 08:13
Are we talking of "warm" ie not fully warmed up from cold?
Or a hot start where you've been riding - stopped for some reason and then want to restart and continue?

The first may need careful use of tickling or choke as the bike still isn't fully warm

But the 2nd usually requires a larger throttle opening to clear the "cloud" of vaporised fuel gathering in the carb/Inlet tract due to the heat of the engine causing the float chamber to vaporise whist the bike is sitting and hot

Of course there could be hot electrics as well