one factor often overlooked when tuning scooters especially when fitting 70/120 kits etc and bigger carbs is that the manufacturer has set the oil pump up to supply oil at say anything up to 40 + : 1 ratio but have to take into account that if you increase fuel flow you also need more oil and many makers of big bore kits specify anything up to 25: 1 ratio so your oil pump will not be supplying enough oil , you can get adjustable oil pumps from TNT but I have seen very bad reviews on them . Premix allows you to be supplying the correct mix no matter what ,so is in my opinion the way to go.
I ran a 26hp runner engine in my typhoon years ago using the std oil pump set up with no problems what so ever, the use of quality oil and warming up and then not giving it death all the time help's immensely.
totally agree with marsh, ive seen new standard bikes last less than 6 months because of cheap oil running through the pump, use proper oil and adjust the pump correct and you will be good for a long time
