Oil injection = more power?

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.


Re: Oil injection = more power?

Ron Brown /


You have not taken into account that the pre-mix is thicker than gas and will flow less total volume. Then factor in the extra weight carried in the oil tank of the injected ped.

I agree, the moon's phase is more significant.


Re: Oil injection = more power?

Kevin Harrell /

Whoops. I left out the weight of the oil injection system too. And the power needed to run the oil injection system.

Boy oh Boy, this question is mor complicated than I first imagined.

Re: Oil injection = more power?

Matt Wilson /

"This would result in the oil injected bike having a mixture richer in gasoline, resulting in more power."

Richer isn't necessarily faster


e: Oil injection = more power?

>> Oil injection = more power?

... Not really .... the way the oil is administered into the motor has little to do with the amount of power generated.

You have to have approximately the same amount of oil both ways right ?

Assuming either choice is correctly tuned... the two engines will make the same amount of peak power.

The correct jetting in motors like these is based on getting as close to the correct "stoichiometric" ratio of fuel to air... (somewhere around 15 to 1 by weight)... that is a chemistry formula based on the quantity of molecules of oxygen correctly matching the quantity of molecules of hydrocarbons.

(you know... like one boy for every girl ... ??)

Moving very far too side (either way... too rich... or too lean) of this correct (stoichiometric) ratio of air to fuel ... results in less HP... So 'richer' doesn't mean more HP.

Since oil injection cuts back on the quantity of oil pumped dramatically during idling and low throttle... there IS however less pollution... (and less visible smoke.. which is good PR).

The oil to fuel ratio in an oil injection system cuts back to almost none at idle and real low throttle

I have seen it listed by the manufacturers as 100 to 1 at idla... and 30 to 1 at wide open throttle.

But it isn't for more HP.

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