First bike I, at 12 years old, owned was a BSA. I think it was a C10 (but may have been a C11, the OHV version).
I pushed it home from where it had been left for years behind a neighbour's shed. A good 500 metres! At the time we lived in an area which had a minimum block size of 5 acres. The exhaust pipe was rated away from just under the engine and there was no silencer, the girder forks needed repairing and the rest of the bike was not much better. The engine was just about seized and the gearbox was blocked. Fortunately it had been left in neutral.
My father gave me a basic set of tools and advice as I went along, he also managed to get a few bits and pieces such as a new head gasket, spark plug and lead, and arranged for a friend to repair the forks. I finally managed to get it all back together and put in fresh oil and petrol.
I had no real Idea of the starting proceedure but I gave it a go and the thing backfired and nearly threw me over the handlebars. Probably too much advance. My father was having a cup of tea and when he heard it fire he jumped up surprised that I had managed to actually get it to a running condition. "It fired!" he said to mum and ran out to the bike. In a couple of kicks he had it running then as it got warm he made some adjustments to the carb. He then proceeded to spend the next half hour riding around the yard on my motorcycle!
I always had trouble getting away from a standing start and it was only years afterwards I realised that I had been starting in second gear because I always had the gear shift pattern reversed in my mind. Given that we were in an area with rough paddocks and dirt roads I on't think I ever got it out of second gear either.