1991 Johnson 25 HP would like to get more power!!!!

[Borgey401]

I have a 1991 Johnson 25 HP model # J25ELEID. I love the motor and it runs awesome with no issues at all. I would really like to get a little more power out of it if that's possible at all. Anything I could modify or anything along those lines to get a couple more HP out of it? I am pretty sure the 30/35 HP Johnsons use the same block as mine but I could be wrong. Any input on the different things I could do to this motor to give me more speed would be greatly appreciated. I have been looking for a bigger motor but just can't seem to find a nice Johnson/Evinrude motor a little bigger then 25 HP.

 

[oldcatamount]

Re: 1991 Johnson 25 HP would like to get more power!!!!

It looks like your motor is a long shaft. Do you need that for your boat? I've seen many people put long shaft motors on a boat that should have a short shaft. It'll slow the boat done condsiderably.

 

[Borgey401]

Re: 1991 Johnson 25 HP would like to get more power!!!!

It actually fits the boat pretty darn good. I can get 20 MPH with 2 people on it (never tried it with just me on board). My boat is rated for a 65 HP max. It gets on plane absolutely fine and it does move I just would like something a LITTLE bit bigger. Just because when I get 3 people on I don't want to stress the motor out a lot if that makes sense.

 

[Borgey401]

Re: 1991 Johnson 25 HP would like to get more power!!!!

Would it be possible to throw a bigger carb on it? I am pretty sure the block is the same as the 30 or 35 HP motors of the same year as mine. I am just not too sure what parts are different from mine to the 30-35 motors. If somebody could point me in the right direction about if this is possible I would appreciate it highly. Also, if it is indeed possible where would be the best place to start.

 

[hidef]

Re: 1991 Johnson 25 HP would like to get more power!!!!

It is possible however I would look around for a 35 or even a slightly larger used outboard. You could then sell your 25 to offset the cost or actually pocket some cash along the way.

 

[JB]

Re: 1991 Johnson 25 HP would like to get more power!!!!

You want to have a better hole shot and go faster. You are getting pretty much all that a good 25 has.

There is a lot more performance to be gained by fine tuning the rigging of your boat and motor than by hopping up and possibly ruining a great outboard.

There are a lot of approaches to gaining full control of engine height and trim, adding setback, optimizing the prop and shortening hole shot. Too many to catalog here.

Add a tachometer, get a perfect, SS prop, add a SE Sport hydrofoil and put them all on a CMC jackplate with PT&T. All of those should be worth another 10-15HP

Or, of course, you can just go out and buy a nice used JohnnyRude 40 or 50 twin looper with PT&T. That is what I would do.

Good luck.

 

[78 mckee]

Re: 1991 Johnson 25 HP would like to get more power!!!!

Very likely that your 25 will perform better with a 30/35 hp carb. That's the only difference between these motors. If you change the Carb you want to make sure that you don't exceed the max rpm by matching the right pitch prop for the power that the motor produces after any modificatons. I have tried this mod and it works pretty well.

 

[nwcove]

Re: 1991 Johnson 25 HP would like to get more power!!!!

Very likely that your 25 will perform better with a 30/35 hp carb. That's the only difference between these motors. If you change the Carb you want to make sure that you don't exceed the max rpm by matching the right pitch prop for the power that the motor produces after any modificatons. I have tried this mod and it works pretty well.

respectfully. you sure bout that 78 mckee? normally a carb swap from a larger hp engine, only uses more fuel.
if the motor is a long shaft, switchiing over to short shaft first "if the transom allows" would be my choice.
(......but if you wanted to experiment, and do a full dissasembly over the winter, and port and pollish the intake and exhaust ports......you may see a noticable difference! ...dont do it. (im gunna take heat fer that suggestion! lol)

 

[tx1961whaler]

Re: 1991 Johnson 25 HP would like to get more power!!!!

Very likely that your 25 will perform better with a 30/35 hp carb. That's the only difference between these motors. If you change the Carb you want to make sure that you don't exceed the max rpm by matching the right pitch prop for the power that the motor produces after any modificatons. I have tried this mod and it works pretty well.

Intake manifolds are different between the 25 and 35.

 

[1969johnson55]

Re: 1991 Johnson 25 HP would like to get more power!!!!

if prop is damaged on leading edge it can seriosly rob power check it can be a good way to pick up some top end also do you already have a hydofoil just some cheap ways to gain just a little.