Velocette 500, electric starter rollers, part 2 FAILURE

This shows the completion of the machine and the testing. Essentially the motor proved not to be powerful enough. The next video will show the adaption to suit the new 2000 Watt motor which is manufactured in the UK.

[@marcomonte3425]

Hello Alan,
I should be very interested to know why and how was it going as I also wondered if it would be a good choice for my bike as you can understand from the following notes.
After Alton electric starter and alternator has been installed on my Velocette Thruxton, occasional but repeated kickbacks at starting or stopping the engine (with no time enough to retard the ignition) damaged the electric starter: “double” gear and polyurethane pins or both with need to replace them with new parts (six months waiting time to receive them !)
Kickbacks were reputed mainly due to Lucas competition magneto deficiencies at low runs - though refurbished - but I am wandering if also GP2 irregularity at low runs could have a role in it
BTH electronic magneto + Amal Concentric MK 2 , 36 mm (a couple well reputed among Thruxton owners as a solution) were effective in stopping the kick backs, may be thanks also to a better designed gear from Alton.
Unfortunately Amal MK2 36mm carburetor revealed to be very difficult to set satisfactorily for unknown reasons (spit backs and engine stalling under 2000 r/m unless you apply the cold starter again) though ultrasonic cleaning and compressed air testing did not reveal air passages abnormalities.
Questions:
- Could reverting to Amal GP give way again to risk of kikbacks or to dangerously overstress the electric starter (quite fragile) ? Or, conversely, would the BTH electronic magneto (setted at 37°) be capable to prevent whatever kickback even if I revert to Amal GP 2 ?
- Is there any safe test one can undertake in order to decide if replacement of GP2 would be without any risk?
- Is that true - as I have been told- that the only powerfull enough ignition system would be a 12V coil ignition with points and high perfomance coils?
- Would it be definitely better any way - "for peace of mind"- to adopt a different type of carburetor from GP for an easy starting in order to protect the electric starter and to avoid the risk (if any) of kick backs arising from GP irregular functioning at low runs?
- Which type and which size of carburetor would be best (for tourism use)? Would you recommand me Mikuni? Which size ? Any problem in installing it?
Thank you
Best regards,

[@alanglen5902]

Thanks for the e mail.
Sadly I think you are mixing me up with someone else. I simply have never had a Mikuni on my Velocette.
I have used Concentrics on many machines, and the problems I have found are:
Float valve leaking , cured by a rubber tipped needle
Pilot circuits getting jammed up with unleaded petrol drying up when not being used. I resort to the ultra sound cleaner to be sure the passage ways are clean on the Velocette. I cured this on my T150 by replacing the carbs with the later carb body which has a screw out cover for the gallery which jams so it can be cleaned.
Spit back / stall at tickover, no real solution here apart from a slightly rich mixture and slightly fast tick over. I remember Geoff Dodkin telling me that Inlet valve opening should not exceed 55 before …. if any sort of tick over was to be achieved. Perhaps the key measurable for performance here is when the exhaust valve opens as that is when the power stops being made.
You mention your engine kicks back. That means you have a good enough spark a kick start speed to start combustion. Great stuff. Now all you need to do is get that spark to occur at the right time so no kick backs take place. …
Say 5 before TDC?? Then ensure your range of advance gets you up to no more than 38 degrees.
I have had no experience of Alton electric starters. Velocette kick back is a potentially dreadful event. I have damaged right hip to prove it.
I hope some of this might be useful.
All the best
Alan Glen

[@marcomonte3425]

Hello Alan,
thank you very much for your experienced and detailed answer
I will try again to do my best for setting the MK2 following your tips
If I couldn't overcome the quoted obstacles, may be a Mikuni could be the choice
All the best