# 20 hp 1989 evinrude tracker motor



## hankthecrank (May 7, 2015)

Hi all. I bought a pig in a poke, motor looks like new , supposedly only used about 20 hours. I'm buying a new boat, a G3 1648 welded hull and I bought this motor to use on it. I took the motor to my local shop to have it looked over. I've been a mechanic for 40 years, so it didn't scare me to work on it but I wanted a boat mechanic to check it out. He called and said he put the impeller in , changed out the gear oil, put new fuel line on and started it up. He had trouble getting it to idle and found the idle screw was installed wrong. Got that fixed and ran it a while then started opening her up. At 3/4 throttle it starts blubbering and acts like it has a fuel issue. Will not run clean, acts like iho that its getting too much fuel. He called me and I remember the seller saying his father in law put the 30 hp kit on it. He also mentioned the prop, something about it being changed as part of the kit. The mech said he thought it had the 30 carb on it. He said he legally can't open the intake up, I could if I wanted to. Now the intake thats on it is the intake with the keyhole slot in the opening so I had already figured on opening that up. I've been looking at part numbers for carbs, jets and intakes and it looks like anything will fit anything. Ive read a lot of the threads already and I think I've got a handle on things, but the part numbers have me confused. It looks like the main jet is behind the fuel inlet and there are 3 different ones. The 20 hp intake is selling for 20.00?, and the other two sell for over 150.00? I've read enough to to make me think I'm gonna open up the intake and try her out. Any thoughts and input would be welcome. Hank


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## hankthecrank (May 13, 2015)

Alright, time for an update. I have the new boat home and have the motor in the shop. Carb # is K0432703, ? and the bore in the carb is 1 1/2 in. However it truly is the 20 intake. The hole in the intake is the keyhole shape and I'll bet its only 3/4 at the most. I'm gonna open that up to match the carb throat. It looks like thats all it needs. Someone already has the bigger carb on it and the prop has been changed to a 10x16. Thats a little more than most guys say they are running, most have a max of 15, but I'm gonna leave that alone till I get the motor where I want it. I found a Johnson 35 locally that has not been run in years so I may look at the intake for the bigger volume. I'll keep ya posted. Hank


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## hankthecrank (Jun 16, 2015)

Alright , time for an update. I've opened up the intake and cleaned the carb really well. It truly is a 30 hp carb. The prop is a 10 x 15. The boat is loaded with the outboard, a 6 gallon metal can , grp 29 trolling batt, Evinrude 3hp Yachtwin for backup, 2 gallon can of spare gas, small trolling motor , tool box , various safety gear and me at 185lbs. This thing rips! I just finished a 30 mile run up the river and back, by myself it gets on plane quickly and flies! I know from experience that it seems faster than real time speed , but I would guess 24/25 mph. I picked up my daughter and 2 grandgirls halfway back and it still gets up to plane, close enough the waves are slapping under the hull,washboardy style. Running slower tho. I didn't run full throttle a lot, the waters up a foot with plenty of trees and limbs in it, but it used less than a full tank of fuel. I'm happy with the whole rig. Easy to launch and load by myself, pulls well on the hiway. Getting ready to go to Edisto Island and fish the tidal creeks and rivers. Might put a bimini top on just for the shade factor. I have three grand daughters. PS. The gas tank gauge had quit bouncing but the motor was still running. Close to a full tank of fuel. I 'm o-k with the fuel use. Prop pitch question. More pitch, better dig and more power? Less pitch more speed? Or vice - versa?


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## kofkorn (Jun 16, 2015)

Lower pitch will give you a faster hole shot and higher top RPM at the sacrifice of top speed. Going to a higher pitch will slow down your take off, but raise your top speed. General rule of thumb is ~500 rpm per inch of pitch. You want to stay within the recommended WOT range for your motor, so you usually only have one or two prop pitches that will keep you in this range.

Good luck!


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## hankthecrank (Jun 16, 2015)

Thanks for the reply! I did the worksheet for the proper pitch prop[ say that three times real fast] and it says a 10.5 x 11 is optimum. I think since this seems to work so well right now I might leave it alone and pick up a 10.5 x 11 for a spare and future testing. Thanks again.!


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## hankthecrank (Jun 16, 2015)

I think I'll rig a tach and see what my rpm is . If I had to guess right now I;d say around 4800-5200. Just an educated ear guess tho. Hank


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## Siguz (Jun 30, 2015)

HEY
Check out these 2 threads. Lots of us have done this conversion to our OMC motors. 
I now have the big carb on my cut manifold and I love it!
Hope some of this info is helpful

https://forum.tinboats.net/viewtopic.php?f=4&t=31894
https://forum.tinboats.net/viewtopic.php?f=4&t=23898


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## Bowhunter1661 (Jun 30, 2015)

I am currently working on my 88 Johnson 25 in order to convert it to the 35. I run 30 MPH at WOT. Hoping to get to mid 30's with the upgrade. Also I am doing the same thing you are. That is enlarging my 25 hp manifold intake hole along with a 35 HP carb. 

A lot of people use Dremel tools or hole saws to cut their manifold intake hole larger. I am going to try and use a rough hone for honing cylinders then finish it off with a fine hone. May take a little longer but it will give me a perfect hole, or at least I hope!


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## hankthecrank (Jun 30, 2015)

The intake material is very soft. I used a round file to remove all the bulk and then a Dremel with a sanding drum to finish it out. Took about a half hr. I used long slow strokes with the file as the intake is pretty thin. I'm at the beach right now with my family and we are having a blast with this setup. With 4 adults and 2 kids it gets up on plane nicely and motors well. With 2 guys and fishing gear its almost too much. really easy to skid around and twitchy on the tiller. Lots of fun tho!


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## onthewater102 (Jul 1, 2015)

From what I've seen the cavity inside the intake manifold is drastically smaller on the 25mph vs. the 35mph, so matching the opening to the carb isn't enough. One of the links above has the measurements, but if you do the math it is a considerable difference in volume. Not saying you won't see results, just that you should still be looking to source an original 35 intake manifold should you get the chance.


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## Bowhunter1661 (Jul 1, 2015)

Absolutely agree. I just cannot find the correct intake manifold for my motor. On eBay most say 20, 25 and 35 fit. When most educated folks know there is a difference not only in intake size but volume between all three. I'm hoping just the hole being enlarged will net me 5hp. Once I find a 35 intake, well, hopefully 10 hp.


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## hankthecrank (Jul 1, 2015)

Very true on volume. I've found a 35 johnson on a boat that hasn't seen the water in 18 yrs. Birds are nesting under the engine cover. I'm trying to bring this home but, I'm watching the computer sources too. I've probably achieved all that can be realized with this setup, the carb is a 30 and the intake an opened up 20. A lot of fun and, my wife and whole family are very happy to be on the water again. Hank


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## Bowhunter1661 (Jul 3, 2015)

Bummer, just found out my 1987 Johnson 25 can only be made into a 30. The 35 in 87 was actually a detuned 40 hp.


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## Bowhunter1661 (Jul 3, 2015)

Does anyone happen to know the diameter of a 35 carb? My 25 carb is about an 1 1/8" the manifold is 1 3/8". The 35 carb I bought has a diameter of 1 3/8". What is strange is the carb in this thread (https://forum.tinboats.net/viewtopic.php?f=4&t=23898) is way 
Larger at an 1 1/2". I am not even sure I have the correct carb because the seller kept the bowl because he said I could reuse my 25 bowl on the 35 carb.


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## hankthecrank (Jul 7, 2015)

I have not seen a 35 carb. I do have a 30 carb and inlet and outlet side are 1 1/2 in. in dia. However inside the carb throat is a small ridge cast in the body which necks it to 1 3/8. This ridge is 1/8 in width and is centered on the fuel inlet tube. Hank


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## Bowhunter1661 (Jul 7, 2015)

hankthecrank said:


> I have not seen a 35 carb. I do have a 30 carb and inlet and outlet side are 1 1/2 in. in dia. However inside the carb throat is a small ridge cast in the body which necks it to 1 3/8. This ridge is 1/8 in width and is centered on the fuel inlet tube. Hank


Intersting, I bought a "35" carb from eBay. Tried crossing the numbers but couldn't match it to anything. My "35" carb is 1 1/2" opening, with the 1/8" ridge in center, and 1 3/8" on the outlet. When I removed my intake to file it down I didn't even have to. My intake opening was also 1 3/8". 

It has to be at least a 30 I would think because the internal throat of my 25 was about an inch. Inlet was 1 1/2" outlet was 1 1/4". This one is definitely larger. Just not sure. The number off the carb bowl is 0322299. 

Sorry to the OP as I kind of jacked your thread. If anyone cares to respond you can always PM me.

Thank you!


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## hankthecrank (Nov 5, 2015)

Hey Everybody! I'm back! Its 77 degrees here today so I spent the day on the water. At 8 am the Ohio river was perfectly flat, some leaves and limbs floating but not bad. My rig is still the way I described previously, but I spent today playing with trim and top speed.The boat was loaded with me, 6 gal of gas, troller and batt. Tool box and various bits of stuff and safety gear. Oh, and a big cup of coffee. I still don't have a tach on board but I did play with the GPS. I initally saw 23-24 mph wide open. Move the motor,manual trim, and picked up 1 mph. moved the gas can and picked up 1 mph. Moved the motor again and ended up at 28 mph. If I moved my feet forward it topped out at 29. Move em back and hold 28. I still have the 15 pitch prop on. At 29 it gently porpoises unless I lean my upper body forward then it smooths out. All in all, I'm tickled.


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## lucescoflathead (Nov 5, 2015)

This seems to be the ticket for running a larger boat on a 20 HP restricted lake.


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## onthewater102 (Nov 6, 2015)

Pretty sure the pigs will be on to you scooting along at 29mph on a 20hp restricted lake...just sayin...but then again, if it's big enough and they're restricted to 20hp you might just get away with it 8)


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## hankthecrank (Nov 7, 2015)

Hey all. Yes, it's suspiciously fast. However, in Wv our lake restrictions are 10 hp or under. I have a 3 hp Evinrude that works for that. The modified 20 is for river running on the Ohio and other rivers. Plus I haul this baby south and fish the bay's and tidal rivers in Sc. Working out good!


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## Moedaddy (Nov 8, 2015)

Bowhunter1661 said:


> Bummer, just found out my 1987 Johnson 25 can only be made into a 30. The 35 in 87 was actually a detuned 40 hp.


I may be wrong but I think my Buddy was able to bump his up to a 35. I'll check on that.


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