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2006 F99MSH2

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p15camborne

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"I've studied Yamaha's

"I've studied Yamaha's online parts catalog. Looks like I can convert my F9.9MSH2 to a F15MSH with a carburetor change for less than $250. The CDI, valves, and camshaft appear to be the same. Changing the carb should be very simple. Even if fuel consumption doubled, this motor would still be economical. It barely sips gas now. What I'm looking for is to get on plane easier. Am I missing anything? Thanks."
 
Intake valves and exhaust valv

Intake valves and exhaust valves use the same part numbers for both engines. Intake - 66M-12111-00-00. Exhaust - 66M-12121-00-00.
 
"From personal experience, you

"From personal experience, you will barely notice a performance increase if any. At top end, on the best day you may (if your are lucky), squeak an extra 3 mph out at the top end.

The main difference between the 9.9 and a 15 is, you can get the top end speed you were used to (with the 9.9) without being at max throttle on the 15.

Out of the hole, I didn't notice any difference (although not tested scientifically), I was able to move up 1" of pitch on the prop (extra expense) and the 15 burns about 40% more gas than a comparable 9.9

Just my two cents - but 250 for a carb and then maybe another 100 for a prop just isn't worth a difference that you won't notice (unless you lie to yourself and say it's there).

For a real performance increase, sell your 9.9 (which is popular and hold their value well) and buy a 20 or a 25 - that you will notice
"
 
"Thanks, guys. Guess I won&#3

"Thanks, guys. Guess I won't try it. I'm not interested in more speed. Just interested in more low end power. My boat is rated for 15 hp max. So 20 or 25 hp is out. I tried an inch less pitch prop, but still a struggle to get on plane.

I wonder if a new Honda 15 hp would work better? The new Honda 15 and 20 hp are the same cubic inches. So maybe it would have the low end power of a 20 hp motor? Also the Honda uses a 4 blade prop."
 
I use a 4 blade on my 15 Marin

I use a 4 blade on my 15 Mariner and a hydrofoil (doel-fin) as well - gets the bow sitting down nice (and up on plane) quite easy.

I run alot of canals with speed restrictions (6 mph) - and found that was the best combination.
 
"Just talked to my Yamaha deal

"Just talked to my Yamaha dealer. I'm going to trade the F9.9 in on a 2-stroke 15. The 15 is lighter and has a better "hole shot" I've read. So should be easier to plane.

Yeah I know I'll burn twice the fuel.
happy.gif
"
 
"Yes, the torque band on the l

"Yes, the torque band on the lower end is a little better on the 15 - just don't expect a big difference on the top end (maybe another 2-3 mph under ideal conditions).

From personal tests, about 40% more fuel consumption - not the end of the world but still a few more bucks a year."
 
Well I decided to wait until s

Well I decided to wait until spring. That will give me time to think about it. One thing I'm considering is a 20 hp. The boat will handle a 20; no matter what the sticker says. I don't believe Tennessee enforces the Coast Guard horsepower. On the state website all they say is the rating is so an engine that is too heavy is not put on the transom. They say nothing about overpowering the boat. Well Yamaha and Honda have 15's and 20's that weigh the same.
 
"Sounds like a wise decision.

"Sounds like a wise decision. A 20 would make a noticable difference and I think you would be happier with it than a 15.

And you are right. The recommendation has more to do with the weight of what is hanging off the back.

I questioned Lund a year ago. A particular 2006 model that was rated for 150 horse was only rated for 115 horse in 2007. I asked why? Their answer was, a 115 4 stroke weighs the same as a 150 2 stroke. So to account for the added weight they lowered the horsepower rating so that the boat would handle properly with the added weight at the stern - nothing really to do with the horsepower at all...."
 
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