1971 Evinrude 9.5hp

[mrbell83]

I want to know if there is anyway to get more power out of my 9.5hp Evinrude. I have synthetic oil in the lower unit, a freshly rebuilt carb and I have tweaked my lean rich knob to its max to run synthetic 2 stoke oil and premium fuel. Have I done everything or is there more?<br /><br />P.S. the motor runs great now, I just want more!<br /><br />thanks.......<br />Power crazy mrbell83

 

[WillyBWright]

Re: 1971 Evinrude 9.5hp

Not without NitroMethane. <br /><br />You can play with reed stops at the risk of breaking reeds, enlarge the intake holes under the reeds at the risk of losing the seal, or drill holes in the piston skirt to align with the intake ports at the top of the stroke, or other radical things that involve tearing the powerhead down. I doubt any of that would be worthwhile. And most would make the motor run badly unless you got everything just right. If you want more power, get a more powerful motor.

 

[mrbell83]

Re: 1971 Evinrude 9.5hp

Yeah, I figured you guys would say something like that, I just thought I would try. I like the motor and I have done a total restoration on it, I don't want to part with it so I will just leave it be and be happy.<br /><br />Thanks for the help.<br />Mrbell83

 

[MCM]

Re: 1971 Evinrude 9.5hp

What octane fuel are you using?

 

[mrbell83]

Re: 1971 Evinrude 9.5hp

Its BP premium so 92 octane........Is it ok to run that in this motor?

 

[MCM]

Re: 1971 Evinrude 9.5hp

Pobably ought to stick with 87 to 89 octane. I think the 92 will burn off too quickly which will give you less combustion resulting in less power. your carbs not jetted for it

 

[mrbell83]

Re: 1971 Evinrude 9.5hp

Thanks for the advise, no other tips on better performance?<br /><br />mrbell83

 

[MCM]

Re: 1971 Evinrude 9.5hp

Not without risking damage to the motor. What spark plug and gap are you using?

 

[mrbell83]

Re: 1971 Evinrude 9.5hp

A standard champion replacement with I believe 30 thousands gap all set by the book. <br /><br />Is there a better plug, or maybe a different gap I could / should run?<br /><br />thanks for all your help,<br />mrbell83

 

[MCM]

Re: 1971 Evinrude 9.5hp

J4J is the recommended plug. Have you done a compression test and if so what were the #'s?

 

[mrbell83]

Re: 1971 Evinrude 9.5hp

I believe it was 110 in the top and 111 in the bottom.

 

[MCM]

Re: 1971 Evinrude 9.5hp

Decent comp. I think what you've got is as good as its gonna be for that motor

 

[mrbell83]

Re: 1971 Evinrude 9.5hp

Thank you for all your help, you wouldn't know what pitch prop I should run by chance do you?<br /><br />Its sitting on a 180lb 14ft aluminum.<br /><br />Thanks for everything.<br />Mrbell83

 

[MCM]

Re: 1971 Evinrude 9.5hp

You can use this link to do a prop selection, just fill in the info.<br /><br /> web page

 

[itstippy]

Re: 1971 Evinrude 9.5hp

You are on the right track by looking at the prop size. Work on "setup" - prop type & pitch, how high to mount the motor on the transom, the angle, using a plate to put it farther back from the transom, etc. Outboard Non-repair board has a lot of info on this. It's a real science to the guys who race boats and the guy with the better "setup" wins.<br />Can you borrow a 15HP and see what difference it makes on your boat? Boats have an inherrent "hull speed" and increasing horsepower doesn't always mean more speed, or much more anyway. If a 15HP makes a dramatic difference maybe look at upgrading. If not, well . . .

 

[wayne h]

Re: 1971 Evinrude 9.5hp

more power = bigger motor <br /><br />these motors are not really made for speed.<br />what prop do u have ? i have 4 props i played with on my 9.5 some giving me more take off out of the hole but the top speed sucked because engine did not get to max rpm others slow out of the hole but max speed was better. if u dont have access to props its gonna be expencive to see what works best on your boat. what is the weight of the boat loaded and what style 14 foot boat do u have ? is the cavatation plate high at the right depth ? is the linkage on the motor set right ? there is a special way of setting up the linkage and throttle on the 9.5's to make sure everything is opening and timing at the right time. i dont think u will find how to do these in any manual other then a factory one.

 

[BoatBuoy]

Re: 1971 Evinrude 9.5hp

Also, a good decarb may be in order using Seafoam or similar product, if it hasn't been done in a while.

 

[mrbell83]

Re: 1971 Evinrude 9.5hp

ok first off, I am running a 14 Princecraft fisherman I think it weighs 180 dry, I figured that the whole package motor and all would be right around 500 pounds read to go. does that help?<br /><br />Also what is seafoam and where can I get it?

 

[ezeke]

Re: 1971 Evinrude 9.5hp

Your boat is rated for 20HP max. <br /><br />Using the 9.5, you will probably find that the lower pitch props (around 7) will still get you on plane if you are not overloaded. <br /><br />I'm running a 9.5 on a 12' Princecraft that I use for clamming.

 

[mrbell83]

Re: 1971 Evinrude 9.5hp

Yes, I know, it is 20hp.<br /><br />thx for the pitch info.<br /><br />The motor has the org. prop right now, 8 1/8 x 8 but I have never ran it.<br /><br />What do you think my top end will be? Is there a specific size that would be best for all around on that boat, I knwo I can't have it all, but close would be nice.........<br /><br />Thanks, <br />Chris