thanks to king marty for the user manual. although its typical of the chinese english. but i still learned a few things from it. and as for the engine cutting out at high speeds, i have tested it by going at high revs on third gear and u guessed it it cuts out intermittently as it did on full speed, so it appears that forchetto was right in saying that there may be a high rev cut out switch, the only way i can think of around that is to change the rear wheel cog to a smaller one. but i'm not ready to do that . Yet. and i suppose i better change that oil pretty soon..