1967 Evinrude Speed Twin 9.5

[Will57]

How can I make my Evinrude Speed Twin 9.5 go faster? Prop, Gearing? Both?

 

[Crosbyman]

these flat top trollers run with low compression and are not road runners .
have you done the basics .. have you pulled the FW to check for cracked coils (common issue)

http://www.leeroysramblings.com/OB%20images/QD_burned_coil.jpg

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[Will57]

Opps, Sportwin

 

[racerone]

It would take a lot of effort to find different gears to go faster.----Lots of beer tokens too.-----First ,make sure this motor is running on 2 cylinders.----They will run nicely on just one.----What are the compression numbers ?-----What kind of boat and how fast is it going ?----No need to look for the mythical 15 HP carburetor for this motor.-----The later reed valve plate might help a bit.

 

[Will57]

She runs very well for a 55 year old engine. I got her for scrap about a year ago and rebuilt her top to bottom just as a winter project. It goes as fast as a 9.5 should I was wondering if there was a way to get a more speed without using more RPM's. That's why I was asking about if there was a different set of gearing and maybe different pitch prop could get me a few more MPH without using anymore RPM's. Thank you.

 

[racerone]

It will take a lot of effort on your part to find different gears that will fit and mesh properly.

 

[Crosbyman]

IMHO... Best to leave it humming along VS causing problems downsream

 

[jimmbo]

That motor was never intended to be Hopped Up. As Racer said the Later Reed Plate might give you a bit more. If it gave more than 2/10mph more, I would be surprised.

 

[airshot]

Your best option is to get a bigger motor !! These little motors are already putting out max power and you wont gain anything noticible after spending big bucks for not much !! Make sure yours is running at its peak, otherwise go bigger...

 

[Crosbyman]

apparently the 9.9 or 15hps are quite different beasts .

your 9.5 is the choice for backwoods lakes , float plate trips etc... if it runs nice you may get a good price to invest in a bigger motor.

 

[racerone]

There is no comparison between that 1964 to 1973 model 9.5 HP and the 9.9 / 15 models that followed in 1974 to 1992 and then 1992 to 2005.

 

[Will57]

I also have a Evinrude 6hp that I saved from the scrap yard that I got running very good. I think its around 1966 or 67. Now that little engine is real slow. Wide open I think I can almost swim faster than what she goes! This is just a hobby for me I'm 65 years old and it helps keeps my brain from rotting out. I find them cheap or free and bring them back to life. It makes my day when I get done and spin that flywheel and they come to life. I'm sure I'll run into a 15hp some day and bring it back to life. Thanks guys.

 

[McGR]

Neither of those motors are speed demons but they should get along at a nice clip when matched with the right boat/load.