I have just recently bought my first road bike. I bought a Yamaha tzr 50. It has been working fine in my garden for last 2 weeks. I went up yesterday and started it, I left it going while I went to get something. I came back and it wasn't running. I tried restarting and nothing, I cleaned the spark plug then it started fine, I left it for another 5 mins to warm up while next to it. I tried to rev it and it just cut out. Then wouldn't start. I cleaned the sparkpug, it started fine left for 5 mins tried to rev and it cut out again. I have no idea what to do, any help is appreciated. The only thing I can think of is that the previous owner used the super unleaded petrol and I have been using normal petrol.

Buy a new plug .

Buy a new plug, then stop wanking it in the garden and ride it properly. Running a 2 stroke like that will generate a 'puddle' (figuratively speaking) of oil in the cases that will snuff out the spark as sure as switching it off. Not to mention an EPIC cloud of smoke when you do ride it as the oil will be everywhere in the system.