GS150 won't start after Vespatronic conversion

Hello, I hope someone can help with this. I have just fitted a Vespatronic kit to my VS4 GS150. There is a strong spark: there is fuel to the plug (very clean carb'): there is compression. The scooter will not fire apart from backfires every few kicks. The flywheel is on tight and the woodruff key is in the right place. Any ideas as to what I should look for next? Thanks for your help (and sorry I only speak English), Peter.

Thanks Dave. I hope it is not that drastic. Can you tell me which VS you have (mine is a VS4)? My kit came with wiring diagrams for VS2 and VS5. Since posting, I have noticed that the two diagrams swap the wiring running from stator to coil around. I had wired mine as per the VS5 diagram: I am yet to try the other set-up. Also, did you go down the GS160 route for a killswitch (it has ten poles rather than the GS150's eight)? Thanks, Peter

Good morning Peter,

it´s important to set the right ignition start-Point.

Your description Shows that you set the wrong time.

Please contact our Hotline or start a callback that we can explain you every step.


How did you guys get on,I had the same trouble. Sorted mine by swapping the two wires round on the coil as the diagram is wrong.