Argyll wrote: Fri Oct 10, 2025 5:59 am Next stage would be to do as @roadster suggested and to check the timing. It won't be a bad idea to do this anyway as you seem to have access to the engine at this stage.

roadster wrote: Fri Oct 10, 2025 10:29 am To be absolutely clear we are referring to a 4-stroke version not the much earlier two stroke engine. If you look at this Ebay item https://ebay.us/m/PMku96 it shows the alternator windings and includes the pick up for the ignition. I'm not suggesting that you need to buy this but locating it on the engine will allow you to check that the rotor, which sits in the centre of the windings, is secure and timed correctly. Because the belt drive is on the left hand side it usually means that the alternator is on the opposite end of the crankshaft. Access may require draining oil and water before removing the right hand side cover. Please note I do not have any specific knowledge of this engine so my comments are no more than hints!