03 25hp johnson prop

[NYGiants]

I have a 2003 johnson 2 stroke 25hp outboard. It has the stock prop and i use it to push a 14' heavy duty lund. (floor and such) i can max out around 23mph factoring the tide out, this is with 1 person at 140lbs. I dont have any problem planing and the trim is the second notch pin in the transom bracket. it is also tiller steer


1) Performance issue you are trying to correct. I feel like this isnt as fast as it should be, but not sure.
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
I am not sure, but its the stock prop.
3) Current prop diameter and pitch (required). 10x13
4) Wide open throttle RPM and speed with an average load (very helpful) I'm not sure of the WOT rpm but the speed is at WOT. and average is load is around 350lbs person weight gear.
5) Engine/drive make, model, year, and HP
2003 Johnson 25 horsepower 2 stroke
6) Boat make model, year, length and weight 1988 lund (pro angler?) 14.6" and weighs aprox 440lbs

 

[steelespike]

Re: 03 25hp johnson prop

It does seem a little slow but within reason.Is speed by gps?
How does the tide figure in.Do you have any speed without tide affecting things.We need to be sure your setup right.
Your Antivent plate(just above the prop) should be visable at speed.
About even with the bottom or slightly above.Be sure the carb is opening all the way.Prop in excellent condition.motor in excellent tune.Bottom clean and smooth.
Without your rpm we can't be sure where the problem is if there is one.
A tinytach is reasonable and easy to install.It will help tell whats up and if your prop change is right.There is a web site. If all is right you may be able to get 27-30 mph.

 

[NYGiants]

Re: 03 25hp johnson prop

1) the speed is with the tide being slack not affecting things.
2) the anti ventilation plate is the way it should be.
3) prettty sure its not the carb issue because when i had issues with it before i only got 12 or so. ( i would pull the primer to open the carb and get to the proper speed) (also know its not the fuel pump) compression is all excellent and the prop looks good except for the everyday minor dings. the paint appears to be flaking off the prop for some reason also.

 

[steelespike]

Re: 03 25hp johnson prop

Are you saying the carb is right now.If you activate the primer now does it slow,
or speed up? Pulling the primer adds fuel,doesn't open the carb.
Different aluminum boats of similar size can have vastly different performance. I believe do to bottom design and construction.Some are loaded with rivets, seams a and keels.
others less so.
I think your gear ratio is 2.23:1 which make a 13" prop about right.
15" prop is the biggest listed here at Iboats 7 is the smallest.That puts the 13 slightly on the high side of the chart.If I was going to suggest a prop without tach info it would be a 12" pitch.Without tach info there is no way to be sure your in the right rpm range.You could allready be near the max. or you could be lugging.
Without a tach there is no way to be sure the motor is at the corect rpm range.
Too high rpm could result in premature failure, to low an rpm could create premature repair problems, poor performance.Perhaps you could borrow a shop tach to run some tersts.

 

[NYGiants]

Re: 03 25hp johnson prop

ill try to get a tach. and the primer knob pulled out now causes it to slow.
obviously without knowing the rpm i greatly inhibit you, but the rpms do sound about right at WOT

 

[qwackhead]

Re: 03 25hp johnson prop

speed is a little low i run a 15X48 aluminum F&F 100gauge with two gun boxes and a floor I could run around 25 to 27 with hunting stuff and 2 people and around 29 empty that is where it would start pourposing. im assuming this is a 2cyl, if so and you want a little more find you a 30hp 2cyl carb and put it on it will give you another 5hp. we run 13pitch stainless solas props their are some better props out their. the solas likes to run a little deep in the water so for a little more $ you can get a prop with more rake and cup to get more performance out of it but you may have to drop to a 12p.
really need a tach to see what your rpm is also have to agree with the other posters it sound like a carb problem or possibly timing advance make sure your butterflies on the carb is laying flat at wot and that the timing adv. rod has not come loose and the plate is moving you will have to do this engine OFF in gear twist the throtle wot see if the timing plate moves.