F8SMHB upgrades

[Cb-otb123]

I have a 2016 F8SMHB and was just looking over the parts diagrams between it and the F9.9SMHB. There are some difference external to the engines but in terms of power, it looks like everything except the carb jets are the same?

Is it really that simple to go from 8hp to 9.9hp? Am I missing anything?

[boscoe99]

How do you know that parts of the carburetor (part numbers unknown) are the same?

[Cb-otb123]

I compared the parts diagram on a different site. They don’t list any ‘unknown’ part numbers.

[boscoe99]

The carburetor assemblies have different part numbers.

There are no part numbers shown for the carburetor bodies. There could be, might very well be, a difference in the bodies.

Adding more gasoline via the use of larger jets does not usually equate to more power. More air needs to enter the engine to agree with the extra gasoline.

I suspect that if you look at your carburetor body that it might have the markings 6FW on it. Indicating that it is for an F8.

Now if you were to buy the F9.9 carburetor it might very well increase the power of your motor. https://www.boats.net/search?q=6DR-1...0&ui=typeahead

[Cb-otb123]

You’re right, I just noticed a difference in the carb number that I didn’t notice before. That makes sense that the carb would be larger to get that extra power. The f9.9 carb has a starter rod that the F8 carb does not have. Is there a control circuit for that, or does it happen automatically?

[boscoe99]

Good catch on the starter rod. The float bowls have different part numbers.

The starter rod is part of the accelerator pump mechanism.

[Cb-otb123]

Which diagram is that in? I don’t see any other fuel related differences.

[boscoe99]

[boscoe99]

Look at the illustrations for the F8SMHB and the F9.9SMHB. For the carburetors. Look at the parts list. The F9.9SMHB uses more parts than does the F8SMHB.

[Cb-otb123]

Sorry, I was referring to the “ accelerator pump”. Is that all contained in the carb, or is there more external to it? My carb does have 6fw11 stamped on it.

I appreciate your help with this. I’m weighing out the possibility of buying the f9;9 carb to see what happens. Just not sure if 1.9hp is worth $350. The dinghy gets on plane fairly easily already.

[99yam40]

just my opinion, but more fuel and air in and maybe less back pressure on all that going out maybe too

[boscoe99]

Sorry, I was referring to the “ accelerator pump”. Is that all contained in the carb, or is there more external to it? My carb does have 6fw11 stamped on it.

I appreciate your help with this. I’m weighing out the possibility of buying the f9;9 carb to see what happens. Just not sure if 1.9hp is worth $350. The dinghy gets on plane fairly easily already.

The accelerator pump is comprised of a number of components. Some external and some internal.

[Cb-otb123]

That looks all self contained to the carb. It amazes me that some one figured out how to make a carb work.

[boscoe99]

That looks all self contained to the carb. It amazes me that some one figured out how to make a carb work.

Although appearing to be simple, carburetors can be incredibly complex. It amazes me what man has created.

Google pressure carburetor. Some are as large as the entire power plant of your F8. https://en.wikipedia.org/wiki/Pressure_carburetor