Upgrade Mercury 8hp to 9.9

[andy k]

I can get a really good deal on a new 8HP mercury. What would be the part numbers that I need to change it from a 8HP to a 9.9? I know it is the carb but I cannot remember the other part that I need.

I know the information on on this site, however I am struggling to find the information.

Thank you in advance

 

[Pirate Lady]

Google is your friend. Bottom line - dont bother, wont make enough difference to make a difference.

https://forums.floridasportsman.com/discussion/192128/how-do-you-convert-a-mercury-8hp-to-a-9-9hp

 

[Pirate Lady]

Some more info here ......

https://www.ifish.net/board/showthread.php?t=948322

 

[andy k]

I currently have a 8HP Yamaha 4-stk. It barley keeps to boat on plate with my wife, son and I. Once we add the beach toys it no longer gets us on plane. I was hoping that the 9.9 would be able to get us by for the next few years. I would think that a 20% increase of power should make a substantial difference.

 

[Pirate Lady]

cant say for sure, we get by with a 7.5' and a 2.6hp. just passing around what i saw on the net but a few years back i had a 10' zodiac with an 8hp Merc, my buddy had same zodiac with a 9.9 Johnson, and there was neglible difference in speed between our 2.

 

[blaster]

It would be much less expensive to purchase a second propeller with less pitch to help push heavier loads out of the hole. Just swap them out when you’re light so you don’t overspeed the motor.