I bought a urban express for $20.00 at a garage sale.It sat for a year or more till I finally got to it. The gas tank was rusted and so was the gas valve, it needed a throttle cable which I found on ebay and a battery.I took care of all that. It started up and runs, but I do not have the right air cleaner for it. I took one off a regular express and it ran better but surges and only gets up to 15MPH. When I disconnect the number 3&4 hose to the back of the filter I can go 25MPH,but I dont know if the oil injector is working.Can I mix gas and oil and disconnect the oil injector and if so what is the mixture I need?