9.9hp 2stroke yamaha

[boater1234]

Hey guys i just had a few questions.The first question i have is i have a new 9.9hp 2stroke yamaha and i have heard from almost anyone who knows these motors that the 15 is the exact same motor except for the reed valves behind the carb.I was wondering if anyone has modified a 9.9 yamaha into a 15?Also was it a major power difference.

The people i bought the motor from said the 9.9 and 15 were so close you really couldn't feel much of a difference.I can't see how that can be true when your increasing your power by 50%.There has to be a big difference wouldn't there be?I mean i know it's not going to be crazy power but i would figure at least 3 to 5mph and a ton better torque at the least.I took my jon boat out today and need that extra power and speed as it is just lacking for the boat i have.It's a 1442 rated for a 25 but i was told from a ton of people a 25 would be to much for a 200lb jon boat so i went with the 9.9 2stroke as they didn't have any 15 2strokes left.I may need to go to a 20hp 4stroke if needed but i'm sure if i modify the 9.9 to a 15 it will do the trick

So i figure if i get it up to a 15 it should be perfect for the boat.

The other question i have is what is usually the best trim to keep it on.It has 5 settings and it seems like the second hole up from the bottom is the best.I was just wondering if anyone has found what works best for a jon boat.I was actually suprised at how much power that little motor had but i need just a bit more and i'm hopeing that a 5hp increase will do the trick.I have also heard once the motor is fully broken in it will perform better with time on the motor.Ok any help would be great thanks guys.

 

[JimS123]

Re: 9.9hp 2stroke yamaha

Not sure about Yamis, but I can tell you the never ending saga about my SeaNymph tinny. Started with a 9 1/2, then a 9.9, then a 15, then an older 18 and finally a 25. All Evinrudes. Trying to get her to go faster, I was never satisfied. The 18 was actually the best motor, but I got greedy again and bought a new 25. That was way overpowered and she acted squirly, so I bought a new boat for the 25, put the 9 1/2 back on and retired the tinny to fishing trips up the shallow creeks where I don't run fast anyway.

But to answer your question, the 15 was the worst investment of the lot because it gave me zilch, nada over the 9.9. I've been told that the 9.9/15 Yamis are basically copies of the Evinrudes, so my guess would be similar results. All the 15 gave me was higher gas consumption.


A far as trim, the 2nd hole always works for me.

 

[boater1234]

Re: 9.9hp 2stroke yamaha

Well don't get me wrong the 9.9 has some good power.I am going to bring it in on monday to modify it to a 15 to see how different it is.Once that is done i will see how much different the results are on my gps.I forgot the gps the last time i went out so i need to do that.Plus when i went on the lake i had me my wife and my child which is a good hefty load.Me and the wife are not the thinest people so i can imagine with just me and gear it will do way better.I'm going to the lake tomorrow to get a good gps reading with just me and gear and then with the family and gear.I will post what it gets tomorrow both ways and then when i modify it we will see if it has a big difference.

 

[boater1234]

Re: 9.9hp 2stroke yamaha

Any other help on this thread???