If you take two mopeds identical in every way, including jet size, one with oil injection and one without, wouldn't the one with the oil injection have more power?
My theory is that the oil injected motor will have more power. The reason being that if the jet sizes both get the same amount of fuel flowing through the carburator. However, the premixed fuel flowing through the carburator would contain less gasoline since the fuel is mixed with oil, while the engine with the oil injection has the oil added after passing through the carburator. This would result in the oil injected bike having a mixture richer in gasoline, resulting in more power.
Please note that the oil injected bike would only get about 2% more gasoline in the mix, so the increase in power would be small. Perhaps so small that the direction and strenth of the wind (and possibly the gravitational pull of the moon,) would have more of effect on speed than the difference of the fuel system.
Just thought that I would throw this idea out there to be kicked around a bit.