Convert 8hp Honda to a 9.9? What's involved?

[Recoil Rob]

I just launched an Amesbury 14 dory this weekend and find that it is underpowered with the Honda 8hp I am using. The engine is a 2006 that only has about 40 hours on it and was just tuned up. It has the smaller 9" prop.

I get up to about 7mph with about 3/4 throttle, and I get no appreciable gain in speed with the final 1/4 of the throttle.

I see that the 8hp is the same engine as the 9.9 except for the throttle range, the 8hp has a full throttle RPM Range of 4,500-5,500 RPM developing 8hp at 5,000RPM, and the 9.9hp has a full throttle range of 5,000-6,000 RPM, developing 9.9hp at 5,500RPM.

Is the difference in the engines due to a governor or are there different carburetors?

How easy would it be to change the 8hp to a 9.9?

Finally, what would be the affect of changing to the 10" power thrust prop, greater hole speed or greater top end?

thanks, Rob

 

[Sea Rider]

Re: Convert 8hp Honda to a 9.9? What's involved?

If both models are same CC, probably need just a bigger carb swap. Check spare parts manual to be sure.

Happy Boating

 

[sdanville]

I read in these same Forums it is a rev limiter chip. I too want more punch from my BF8. So did anyone actually try a carb or black box swap ?

 

[GA_Boater]

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