Actually you should be right really, unless it is very long wheel stand. If the return pump sucks air it wont matter. If the oil doesn't run into the pressure pump, that's where you will have a problem. Hell, I have a customer who did 70000kms on a 200hp motor and he did rollng burnouts, wheelies etc every time he got on the thing with no problem. We just built the engine, dynoed it and rode it straight away, no run in. The only reason he stopped it was because he shot one of the gearbox gears to bits. I reckon it is something with your individual bike. What weight oil are you using?