When the engine is tilted oil can get in the air filter and fill the carby fuel bowl ,I'd remove the air filter just to start the motor
but also remove the fuel bowl and tip the oil out and then bolt it back onto the carby and try starting the motor without the
air filter ,that way you can pour a little fuel down the carby throat this will make starting easier.
(your carby probably has a fuel drain plug on the side of the bowl that you could remove and drain the carby then fit the bolt back in , if you do this you won't need to remove the fuel bowl to tip the oil out)
Check the air filter isn't covered in oil then fit the filter after the motor is running.
Cheers
Max.
