oil block off jetting question

[Blaaster]

While running richer will not harm anything, I still stand by not upping the main jet.

The lack of oil in the fuel/air mix entering the crankcase prior to block off is compensated by the addition of oil to the fuel.

Even though the air/fuel ratio mixed in the carby will be leaned by 32:1 premixing, no oil will be introduced to the air/fuel mix delivered to the crankcase. Therefore the final mix delivered to the crankcase will in theory be richer than the stock injected 24:1

Am I wrong in thinking that no matter where the oil is put into the system, the final mix that goes into the crankcase is what matters?

 

[xjma]

While running richer will not harm anything, I still stand by not upping the main jet.

The lack of oil in the fuel/air mix entering the crankcase prior to block off is compensated by the addition of oil to the fuel.

Even though the air/fuel ratio mixed in the carby will be leaned by 32:1 premixing, no oil will be introduced to the air/fuel mix delivered to the crankcase. Therefore the final mix delivered to the crankcase will in theory be richer than the stock injected 24:1

Am I wrong in thinking that no matter where the oil is put into the system, the final mix that goes into the crankcase is what matters?

The way I understand it (and someone correct me if I'm wrong here) is that the air/fuel ratio is determined by the carb jets (main or pilot, or the needle and main, or whatever combo thereof depending on throttle position). when you have the injection system, the injection of the oil into the carb doesn't affect the air/fuel ratio because it happens after the jets, and pure unmixed fuel goes through the jets. the oil comes in after the air/fuel ratio has already been determined. once the air/fuel/injected oil gets into the crankcase, the oil drops down into the crank for the most part as well, so your air/fuel ratio is as it was basically before the oil was introduced.

When you pre-mix, the fuel/oil mixture is passing through the jets, so you're getting less actual fuel in your air/fuel mixture going into the motor. Then, on top of that, a good amount of the oil drops out of suspension in the crank itself.

So in theory, as I understand it, dropping the injection is going to lean you out a tad. how much will depend on your setup, location, etc, etc. I believe that I did go up on my main when I did the block off, but it's been a while.