change a 2001 honda 8hp to a 9.9hp

[captaindarian]

Does anyone know how to convert a 8 hp four stroke honda to a 9.9 hp? <br /> It seems to me that the Honda bf 8 and the bf9.9 are exactly the same. Exhaust valves, engine weight, pistons, etc. They turn 8 hp @ 5000rpm and 9.9 @ 5500rpm respectively. This leads me to believe it is a carberator issue. My outboard is a 2001 model. I just need a pinch of a tad more to plane my dingy since my son has grown into a five year old appetite. I already installed tabs. <br />Thanks, <br />Darian

 

[WillyBWright]

Re: change a 2001 honda 8hp to a 9.9hp

Welcome to iboats and What is your dingy rated for?

 

[Silvertip]

Re: change a 2001 honda 8hp to a 9.9hp

A Honda guru will stop buy eventually, but while going from 8 to 9.9 sounds simple enough, that is a 25% increase in HP. This question gets asked alot. Four strokes make power using variations on cam, compression, and carburetion/fuel injection. Carburetion being not just the carbs but the induction system as well. It may very well be only a carb swap, but I would bet its not. A little more ignition timing may be part of the equation as well. Every manufacturer has at least two and often three or four HP ratings using the same engine displacement. That does not mean everything internally is the same across the line. If that were the case, manufacturers would sell no bigger engines as everyone would pay for the smaller one and simply "tweak" it.

 

[captaindarian]

Re: change a 2001 honda 8hp to a 9.9hp

Originally posted by WillyBWright:<br /> Welcome to iboats and What is your dingy rated for?

I have a 500 ton master ticket. I dont need a safety course, but thanks for the concern. The avon is rated for 10 hp. Back to the question, has anyone heard how to do this?

 

[captaindarian]

Re: change a 2001 honda 8hp to a 9.9hp

Originally posted by Upinsmoke:<br /> A Honda guru will stop buy eventually, but while going from 8 to 9.9 sounds simple enough, that is a 25% increase in HP. This question gets asked alot. Four strokes make power using variations on cam, compression, and carburetion/fuel injection. Carburetion being not just the carbs but the induction system as well. It may very well be only a carb swap, but I would bet its not. A little more ignition timing may be part of the equation as well. Every manufacturer has at least two and often three or four HP ratings using the same engine displacement. That does not mean everything internally is the same across the line. If that were the case, manufacturers would sell no bigger engines as everyone would pay for the smaller one and simply "tweak" it.

Thanks for the imput. I believe all the internal components are the same including valves and all. I think the reason they make a 8hp is because a boat under 8 hp does not need to be registered in FL. The price is about the same. Again, Thanks.<br />Darian

 

[boater4life]

Re: change a 2001 honda 8hp to a 9.9hp

I've heard throught the grape vine that the difference between these newer outboards is just a rev limiter chip.

 

[sdanville]

Dear Captain Darian Did you ever get the extra couple horses out of the Honda BF8 ? I have the same motor and it runs like a 9.9 but maybe there is more punch available, Steve

 

[GA_Boater]

sdanville - you are talking to an empty room. The original poster has not posted again since 2005. Please do not reply to topics with no activity for 90 or more days. Thanks.