1997 johnson 90 stock prop pitch?

i just picked up a 97 larson flyer 166 16ft with a johnson 90 outboard.

it has an aluminum prop currently that i am looking to replace, but i am unsure if the pitch is the correct one or not that originally came with the motor. it currently has a 14x19 prop on it now.

does anybody know the stock pitch? i ordered an owners manual for it but haven't gotten it yet and i have had no luck with google.

the current prop is chewed up all to hell and i want to start with it before going any further into fixing anything else.

@ wot it only goes to about 4200 rpms and about 36mph give or take. i know a bad prop, may cause this. i also had the motor trimmed all the way down too, not sure how much that makes a difference.

any suggestions?


also i have read that the 90 is and untuned 115? any truth to that? if so what can i do for the extra hp?

any modifications i can do that will help me along those lines? plugs wires and what not are all new.

this is my first boat and just looking for some imput.

thanks in advance.

Re: 1997 johnson 90 stock prop pitch?

98tib, welcome to Iboats prop forum and we will try to help you as much as we can but without more information no one can help you, and I will tell you I need more information than anyone else. But if you would like my help fill this form out and I will help you as much as I can, if you would prefer to not go to this much trouble there are other people who will help you.

Iboats Boat and Motor Info
1. Year, make and model of boat
2. Length, width and base weight of boat, look for boat decal on back of boat
2a.What is the recommended HP for your boat
3. Number of people and gallons of gas normally on boat
4. What do you use the boat for
5. Is it a Deep Vee and if so how many degrees of deadrise
6. Year, make and model of motor
7. HP and gear ratio of motor IMPORTANT
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing and turn the motor until the tape lines up with each other, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
8. Manufacturer?s recommended Wide Open Throttle (WOT) range
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches
10. Is it a bass boat or does it have a pad bottom
11. Does it have a hydrafoil, dolefin or trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. If you do not have a tach you can buy a Tiny Tach for $ 50
14. Are you at sea level or a higher elevation, give us the elevation in feet
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way, checked compression, and looked at the plugs and checked spark, all of the foregoing could be the reason your prop is not attaining full RPM
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop
17. Does the prop show any damage that you can see
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations
19. If you are trying to attain a better cruising speed and fuel savings or trying to attain a faster speed I will want you to take your boat and run it with 1 or 2 people and give me the RPM and speed readings starting at 3,000 RPM in 500 RPM increments all the way to WOT.

REMEMBER, The numbers I give you will be NO better than the information you give me

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.


H

Re: 1997 johnson 90 stock prop pitch?

Iboats Boat and Motor Info
1. Year, make and model of boat - 1997 Larson flyer 166
2. Length, width and base weight of boat, look for boat decal on back of boat 15 feet 11 inches i think is the exact length, 7 foot 3 inches wide,weight is about 1080.
2a.What is the recommended HP for your boat - i do not know
3. Number of people and gallons of gas normally on boat 2 people and 16 gallons of gas
4. What do you use the boat for - fishing/tubing/skiing
5. Is it a Deep Vee and if so how many degrees of deadrise - i do not know
6. Year, make and model of motor 1997 johnson 90
7. HP and gear ratio of motor IMPORTANT 90HP 2:1
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing and turn the motor until the tape lines up with each other, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor
8. Manufacturer?s recommended Wide Open Throttle (WOT) range 4500-5500
9. Anti-ventilation Plate height above keel of boat if it is an outboard in inches sorry i do not know that either
10. Is it a bass boat or does it have a pad bottom its a runabout
11. Does it have a hydrafoil, dolefin or trim tabs trim tabs
12. Make, model, diameter, pitch and whether SS or aluminum prop - 14x19 alum prop
13. WOT RPM and speed from your current prop and how much gas and how many people were in the boat for the test data and is the speed by GPS. If you do not have a tach you can buy a Tiny Tach for $ 50 - 4200rpm @ 36mph 16gal of fuel 2 people in boat
14. Are you at sea level or a higher elevation, give us the elevation in feet - sea level
15. Has your motor been tuned up lately and have you checked that the carburetor butterfly is opening all the way, checked compression, and looked at the plugs and checked spark, all of the foregoing could be the reason your prop is not attaining full RPM - tune up done within the last 2 months, spark ok, have not checked compression
16. How long has this prop been on the boat and why, at this time, do you think it is the wrong prop - i just bought the boat i do not know how long it has been on there, i do not think its the wrong prop - just looking for the right size that should be on there, the current prop is all chewed up and neds to be replaced and since i can only get to about 4200 rpms i know prop size can be a big factor as to why.
17. Does the prop show any damage that you can see - yes, its not bent or anything just chewed up
18. What problems are you trying to cure or what are you looking for the boat to do that it is not doing the way you think it should or to your expectations, be where it shoudl be performance wise - operating range should be between 4500-500 rpms and i am not
19. If you are trying to attain a better cruising speed and fuel savings or trying to attain a faster speed I will want you to take your boat and run it with 1 or 2 people and give me the RPM and speed readings starting at 3,000 RPM in 500 RPM increments all the way to WOT. trying to attain proper crusing speed @ the correct rpms, its gets to the 4200 rpms pretty quick with 2 people, i do not know exact rpm to speed #'s tho, if i had to guess 3k 30mph 3.5k 33mph and 44.2k 36mph??
REMEMBER, The numbers I give you will be NO better than the information you give me

The only thing I ask of you is to come back and give me a report of WOT RPM and speed for my database.


thank you for you help

Re: 1997 johnson 90 stock prop pitch?

does anybody have at least a good recomendation for a new prop? i want to stay with an aluminum 3 blade for sure.

Re: 1997 johnson 90 stock prop pitch?

I've got a 15 ft fish-n-ski with a 1981 Johnson 90. The prop is a 13-1/4 x 17 3 blade aluminum which I believe is original, and it works well with my boat (around 5400 rpm wot). I'd guess that a 17" pitch would be pretty close for you as well. Your boat is a couple hundred pounds heavier than mine, but at the same time your "90" will be putting out a little bit more power than mine.

Re: 1997 johnson 90 stock prop pitch?

98tib, I ould make a reommendation now but I am not sure it would be right. You need to take the boat out again and trim the motorup as high as you an until it starts ventilating and then run it down just a fration to stop the ventilation as this an make a differene of as muh as 500 RPM and I need to be sure what the maximum RPM you are reahing with it trimmed out.


H

Re: 1997 johnson 90 stock prop pitch?

hwsiii said:

98tib, I ould make a reommendation now but I am not sure it would be right. You need to take the boat out again and trim the motorup as high as you an until it starts ventilating and then run it down just a fration to stop the ventilation as this an make a differene of as muh as 500 RPM and I need to be sure what the maximum RPM you are reahing with it trimmed out.


H

Click to expand...

well lets say worst case scenario that i am losing the full 500rpms, i am still only reaching 4700rpms max.

i am taking the boat back out with some family from out of town, so i will make a few runs then, trimming up and down to see how high i can get the rpms to go.

in the meantime, last night i measured the distance between the prop blade and the lower unit and there was only a 1/4 inch gap between, is it normal to have such a small margin of error there? i keep hitting up numerous sites to buy a prop and it looks like the 14x19 i have is never listed anywhere but usually either a 13-13 1/4 x 13-17 at most. i am thinking that i should change out for at least a 14x17 or a 13 1/2 x 17, what do you think?

Re: 1997 johnson 90 stock prop pitch?

First, understand that there is no "standard" prop for your engine. In fact the engine was shipped from the factory without one. The reason for that is that the manufacturer has no idea what boat (barge, pontoon, deck boat, V-hull, inflatable, etc) the engine will be installed on. Each of those rigs would likely require a different prop for optimum performance. You need a 13-1/4 x 17 three blade for general operation. With a light to medium load that should put you in high 30 mph at 5500 rpm. That all depends on the hull design, whether it's clean or not, and whether or not the engine is developing full power.

Re: 1997 johnson 90 stock prop pitch?

Silvertip said:

First, understand that there is no "standard" prop for your engine. In fact the engine was shipped from the factory without one. The reason for that is that the manufacturer has no idea what boat (barge, pontoon, deck boat, V-hull, inflatable, etc) the engine will be installed on. Each of those rigs would likely require a different prop for optimum performance. You need a 13-1/4 x 17 three blade for general operation. With a light to medium load that should put you in high 30 mph at 5500 rpm. That all depends on the hull design, whether it's clean or not, and whether or not the engine is developing full power.

Click to expand...

I thought i read that somewhere about not being shipped with a prop, thank you for the confirmation on that.

so if i stick with the 14 dia. and "downgrade" to a 17 pitch that should be fine then?

also @ 5500 rpms you said high 30's or did you mean 30 at the highest?

right now i can get to 35mph + or - @ 4200 rpms with the 14x19 so i figure 14x17 should send me over the 40mph @ 5500 rpms no problem right? does that sound right? or am i misunderstanding something here?

is there any benefit to going with a smaller dia prop?

sorry for all the questions this is my first owned boat and i never had to worry about all this when driving someone elses.

i appreciate all your answers thus far.

i am trying to seach this site and various others and googling every combination of words i can to try and get some knowledge on this stuff. i have been a car guy forever and i am decently knowledgeable in automotive but the boat thing is going to take me some time to get acustomed to.

again thank you.

Re: 1997 johnson 90 stock prop pitch?

what will be sacrificed when/if i go with a smaller diameter prop?

Re: 1997 johnson 90 stock prop pitch?

98 try reading this if you would like to learn a little more about props, it has some tehnial terms in it but hopefully it will give you a better understanding of some of the priniples and problems involved in propping a boat orretly.

http://forums.iboats.com/showthread.php?t=303221


H

Re: 1997 johnson 90 stock prop pitch?

so i finally settled on a new prop. I picked up a MERCURY MARINE Quicksilver Johnson Outboards Prop. 13 1/4 x 17.

all i can say is WOW. between the new prop and learning the whole trimming thing, i gained 1000+ rpms and almost 10 mph and thats with an additional person since last time a tried.

thank you for all your help and advice