Conversion of 1983 9.9HP to 15HP for Johnson / Evinrude / OMC Outboard
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- เผยแพร่เมื่อ 13 ก.ค. 2024
- Your 9.9HP Johnson or Evinrude outboard motor is a de-tuned version of the 15HP motor for 1983 and many other model years. The 9.9HP power head and lower unit components are all rated for 15HP, but the carburetor restricts RPM's and limits the engine's power.
Convert your 9.9HP outboard to 15HP by exchanging the 9.9HP carburetor with a 15HP carburetor. The difference in these carburetors is the larger diameter of the throat opening on the 15HP. This allows for more fuel to be sucked into the engine thereby achieving higher RPM's. - ยานยนต์และพาหนะ
Without the exhaust mod you won't have 15hp
I have a 15 1986 model evinrude. then I bought a beat-up 15hp tohatsu 1990. what a slam-dunk difference.... the tohatsu is an animal! and don't get me started on the 18 tohatsu. what a beast.
A really good video. I use a one gallon ultrasoni cleaner to clean the carburetor, the ultrasonic litterature says to never use flamable fluid in the tank, but I do anyway, I've been doing it for very long time and no fires yet.
Excellent modifications on that 9.9.. excellent video.. my only thoughts were you should have run this on the same boat before and after.. thank you again 😀😎
Tape the starter pulley together and remove the middle bolt to gain access to the port carb nut.Use silver solder to fix the hole in the float bowl, or JB weld!
The easy way to do this is buy a 15HP and then find a 9.9 hood on Ebay. Way easier and you will get to stay under the 9.9 state limit for registration.
Not true, u still need to put 9.9 numbers on the side of the motor mount, 15hp have different numbers
And to change those numbers it's just as much work as replacing exhaust tuner, carb and Reed spacers
I have a 1978 9.9 John long . I see you have 473 videos. Do any of these videos show how to change the grease seals on the prop shaft ? I pulled the prop ,the two 3/8 bolts made a puller & pulled the two bolt housing. Looking down in they'er i see a puddle of grease. If i turn the motor over to drain the grease will anything else fall out that i have to worry about ? Thanks .
Note on older 9.9 and 15's the 15 had a TUNED EXHAUST tube that boosted output about 10% or roughly 1.3 HP at the top end. Word is that OMC switched to that exhaust tube on both 15 AND 9.9's later on.
1983 just need carb 84 and up need tuned exhaust etc. where can i find a 15 carb?
This is good info, whether it becomes an actual 15hp or not... where I live (Colorado) many small lakes are restricted to "10 hp max" and a 9.9 is really weak at altitude. Seems like this might make up for some of the losses, while still remaining legal.
Hi! I have a Johnson 15 hp " Seahorse" from the late 80's. It flyies with a 3 meter zodiak and 3 people on board.
It has been sitting for some 15 years . I ' ll clean the carb and replace the water pump impeller.
It was used 3 seasons in crystal clear lakes water.
Apart from this and changing the gear grease ( oem) and spark plugs ,do You
think of anything else ? Thanks in advance ! Cheers!
those old johnsons are nice but every time I see a video like this it makes me appreciate my yamaha that much more.
Idle, Main, & Air Bleed Jets, Throat Diameter of the carb body, Tuned Exhaust, & perhaps the Spark Plug heat range...
hi i have an 1984 9.9 the same motor but 1 year older it was sitting in a shed for about 30 years i have got it going it starts 2nd pull would you recommend that i do anything to the motor. Im am in the middle of putting a new water pump and impeller on it and was thinking of putting a 15hp carb on it
Hey buddy.whats the red piece that is like behind the coil? Mine is black and it has a little spring that came off and don't know how it goes.can u make a video what it does or is and how it goes?
I have a mid 80s Evinrude 9.9 that I'd like to know what the sequence is for getting to the motor mounts. Can you give me an Idea? does the powerhead need to be removed first?
The motor runs great, but is ready to fall off! its so bad that the sag is pulling on the throttle cable and ruined it, so gotta replace that too. Please help !
Thx
I have a question would it be possible to but a larger carburetor on a 4hp Johnson year 2000 2cycle 2 cylinder?
Just use a 5/8" socket and remove the starter recoil assembly as an assembly to get to the other 7/16" nut. Much easier. Also use a 4 way open end wrench for this application
and put a nut on the rewind spindle bolt to hold the rewind together while you have it separated from the engine.
I have a 1994 johnson 9.9 2stroke short shaft are the 15hp the same as the 9.9 for bolt on mods?
That main jet is a no. 56 on the 15 hp as opposed to a no. 38 on the 9.9.
how is the best way to change(acess) the cooling water outlet on the engine block( it broke) old one I mangaged to unscrew, but not so lucky attaching the new one without loosening the whole 'schubang'
I upgraded my two stroke Tohatsue 2.5 hp to 3.5 they look the same but 2.5 was direct drive and 3.5 was F and N. All I did was remove large blocking washer In the throat of the carburetor .. Revs much easier, nothing else needed...
Is the mixture knob the idle pin for the carb? My engine seems to bog out at idle unless I give it throttle. I’m guessing it’s my idle pin
I have a 75 9.9, do i read correctly that I can just change the carb and not have to do the exhaust or anything else?
How does the choke knob disconnect, went a bit fast. I have an '83 E'Rude 4.5 looks similar. All plastic I don't want to break anything removing it. Need to do a carb rebuild. Thanks
I did the same upgrade but just changed out the main jet and it changed the performance dramatically.
Where did you get the main jet from?
@@JiggyC The local OMC dealer in Mobile. Bought 2, the next size up and then the next larger one that had the same OD. Don't recall the ID of either but the larger one didn't perform but the smaller ID was great. A friend of mine with his brother was in a 14 ft with a 20 Merc and I was in my 14 ft and could slowly pull away from them.
One other note: in Europe they called the restricted motor a "ten hp" not a "nine point nine' and apparently they used the exact same 15 hp carb with a restrictor plate between the carb and reed block making the conversion a simple matter of removing the restrictor.
Is the main jet the same or do u need to change aswell have a Johnson gt10 with restrictor plate
@@paulotoole9314 I've just bought a GT10 and will be checking for the carb restrictor tomorrow. Let me know if you find out anymore info. Just removing the restrictor plate seems a bit too easy
@@RobBoothAutomotive no difference in power actually runs better with plate on
@@RobBoothAutomotive the difference between a 15 hp ( APBA )"A" motor and "J" CLASS motor is the restricted plate !!!!! If I remember correctly the plate hole was 1/2 " or 3/8 ".
This was done so that o e motor could be used for the younger kids to get into boat racing had a place to start due to age restrictions on the class A. Or 250 in the PRO division both hydroplane and runnabout classes.
So could I do this to my 61 18hp Johnson to a 25hp or can I just put a different powerhead on it like 35hp
Great vid! Can I upgrade my 9.9 1976 Johnson?
You might call it half assed, but I simply used a cold chisel and tapped that inside nut off. Then re tapped it tight to same position
Hey where are you located?
I looking to get some work done on my johnson outboard 15hp
Later carbs have a plastic bowl and they used seven screws to hold it on; probably to avoid leaks 'cuz you can't tighten down as much on a plastic part.
Just carb swapped my 82 9.9 with a 1980 15 hp carb and man does it sound peppy. Gonna do the reed shims probably during winter and maybe an exhaust if I can find one
Was it worth it?
@@timramirez1175 if you have the parts laying around to do it then it’s definitely worth it. Huge gains
Can we do this to the 1993 Johnson Outboards 9.9 [ J10RETM ]?
the later models late 80's early 90's. The 15 had tuned exhaust he said this is a 82 model it should be the same exhaust
how do you change a 15hp thermostat
Look like on these It has the pisser which is a hose hanging right ? And then on the direct back upper there is a hole where exhaust comes out above water Now out of that hole should water be pissing out or misting out with the exhaust and shoukd the amount of mist be more with the more throttle given and shoukd it be misting immediately after start up ?
Johnson and Evinrude piss water...Yamaha trickle...
My father inlaw had a 79 or so Johnson motor. Is buy the older motors better? Like buying old school cars easier to fix and last just as long?
All plastic and rubber parts in older motors need replacement; time and parts invested make buying a new outboard competitive esp for peace of mind.
Tuned exhaust
Say would this work with a 9.5 hp evinrude sportwin
I was tired of the 9.9 slug so I picked up a 15. It was a nice improvement but wanted to do the conversion to bypass some laws. I did exactly what you did with these same motors and didn't notice any gains. During disassembly of the exhaust, the 9.9 appeared to have the better one but that's just from the looks of it so I decided to keep it. I hear something about different reed valves? Not sure what that is yet. Anyone have anymore suggestions?
Some 9.9's had the same tuned exhaust; OMC probably came to the realization that stocking and assembling two different ones made no sense on their production lines.
Hi when i remove the high speed jet there is a jet under that hows remove it the grove for flat top screwdriver is stripped out
Ok, so if you can do this with the 9.9, can you put a 9.9 carb on a 6hp to increase its power also?
Gary dont think so as its a different block
Hi. From Oz here. I have a 1981 Johnson 7.5hp Model - J8BALCIC. It looks very similar to the 9.9hp. I was just wondering if that can also be upgraded?
i know this is super old, but what the heck. some info for ya: to upgrade your 7.5 (which in 84' was downgraded to a 6hp while they added a true 8hp to keep up with the japanese aka the 7.5 is exactly same as an 84' -'91 6hp) you need the 8hp (various years will fit) cylinder head and carb part 395139. might have different WOT timing, but check your service manual. good luck!
Can u help me to fix a 55 Johnson evinrude rewind starter the hold set up
Does anyone know the conversion carb part numbers??
And...what you think about the conversion of a model year 2004 9.9hp in a 15hp?? The displacement is 255cc...
Should be easier...or not?? Ciao dall Italia, and forget my terrible english please...😇
A 7/16 snap on 1/4 driver universal socket with 6in extension will take carb off
I once took my carb off on the Columbia river with a leatherman tool. I think a piece of rubber or something clogged the main jet. It was Johnson 15hp
Will this work on a 1981?
You never make a video testing the motor in the boat how running
You have a 12 hp engine unless you added the reed spacers.
also you should not soak a omc carb. Only use spray berrymans or any carb and choke spray. the emulation tube was epoxied in from factory this is straight from omc recommendations back in the day. It was taught in ob1 class the first of many years of classes. also just like you when I was a young man fixing these in my garage i thought same thing but as others said tuned pipe and port timing is different. Another tip! in barrels exhaust gasses build and they load up. put a fan blowing fumes away and they will tune better in a barrel
If you really want to go lux, avoid the harsh chemicals and use an ultrasonic cleaner.
tried it but it bogs down at half throttle there must be other parts that need changing
Damn I wanted to see the differences in 9.9 and 15 carb 😩
I just got a 1978 evenrude 9.9 and I am trying to figure out what carb I have , what do I need to look for the opening of the carb measured 1,3/8 inches
According to Leroy at www.leeroysramblings.com/Johnson%209.9_15.htm
"The 9.9 hp carburetor’s INTERNAL THROAT is .625 dia., 15 hp internal throat is .875 dia. up until late 1987 when they went to a plastic topped carburetor."
that's called a venturi...the 15 has a larger venturi ..don't know but thinking it must have a larger main jet for more gas too..
Oilsmoke Jones confirmed on an 87 👍
Yeah, the jet is bigger - producing 15 pones takes more fuel than 9.9. But, you can't just rejet a 9.9 carb - all you get then is a gas pig that bogs!
would you be interested in selling the starter of your 15 hp parts motor? also I have a 1967 6hp Johnson. is there any upgrades I can do to it?
Ben Boland the 6hp you can port and polish the intake and exhaust areas and the carburetor you can get a bigger main jet in therory more air more gas more bang also sanding the head down and the top cast marks on the piston tops
I have a 1974 Johnson 9.9 and I just converted it into a 15 horsepower Johnson 1974 carburetor so they are the same year and only got maybe a 1 mile per hour increase but I do notice it has more torque. but I'm not quite sure i shluld documetned speeds wuth weight before converting. but with just my self with a 9.9 on the 14ft v bottom I went 19.5 and with the 15 horsepower conversion same engine i went maybe 20.5 could someone tell why that is. i expected atleast a 2-3 top end speed 22.5 or 23 from 19.5 is it my prop or something. i did this conversion for more top speed which i guess im pretty happy with torque it gave me
Actually, you won't get 'more torque' 'cuz everything about the motor including bore, stroke, porting, is the same. If anything you might LOSE a bit of torque at the bottom end as you're giving up a bit of intake vacuum with the bigger carb.
HP is your torque times how fast it does that effort. Max RPMs are the same on a 9hp or a 20 HP. To go faster you have to use that torque at the prop.
You have the right prop when you can reach Max RPM but going to a steeper pitched prop won't reach Max RPM at fill throttle. The 15 HP motor is faster than the 9.9 HP because the prop has a steeper pitch. A shallower pitch will increase RPMs and or lower your speed, but will not cavitate as easily. If your boat can't reach Max RPM, can't get enough power to get you on plane, or cavitates the prop, go to a shallower, less aggressive prop.
I have a 1990 evinrude 15 hp runs perfect are there any carb adjustments I could make to bump it up to about 20 hp?
no easy way to do that, I'm afraid.
No easy swaps. You have a 13 cubic inch engine. Older 20's had a 22 cubic inch displacement. So, you're probably getting all the SAFE power you can out of that mill; remember you're turning 6,000 RPM to get 15 ponies. Odds are the crank and rods wouldn't take much more - at least not stock ones and maybe somebody makes hot-rod internal for these motors but I'd kind'a doubt it - unless enough people actually race 'em.
@@russg1801 7,000 RPM as per my factory service manual!
Are the props the same between the models as well?
Can you do the same for a 5.5 evinrude fisherman to a 10hp.?
Nope, just buy an Evinrude Sportwin 10; they're cheap enough! I have a 1959 Golden Jubilee 10 I'll sell you for $450.
while they are very similar they are completely different motors. The exhaust tuner under the power head on the 15 and the 9.9 are completely different. 15 horsepower has two water pickup tubes and 2 grommets under the powerhead. The intake is completely different. If 9.9 has a smaller opening than the 15 horsepower. They are still very good motors
1992 and older you'll have to replace the exhaust tube. 1993 and newer you'll only need to replace the carb. But not a true 15hp unless you replace the exhaust tube.
THeres a lot more to it than just sticking a 15HP carb. THe engines porting is different. I gaurentee that a normal running 15HP will eat a converted 9.9 any day of the week. Same goes for the 6 to 8HP conversions. The blocks are different internally where you cant see them.
+smoke skull I think the point of the video is to show how a $150 part can deliver some extra power to owners of 9.9HP stock motors who don't have the dough to dish out and buy a full-fledged 15HP setup.
+highlandoutboards the 15hp has tuned exhaust pipe that 9.9hp don't also.
Interestingly enough a few different sources say it depends on the year, I cant remember exactly but if you have a 1978 or earlier it is a straight swap, others will give you like 1 to 3 and better acceleration if they are on later motors. A guy on one of the forums measured his top speed and acceleration difference was a fair amount (i believe his top speed went from 20 to 26 and I cant remember if it was KM/H or MPH). I also herd that the timing is different, meaning a general tune up after you install it will get you (relatively) the 15 HP with the swap.
I rebuilt both an 87 and an 89 the power heads were identical everything was at least for these years exhaust and carb were only difference
justame smith pull powerhead and replace the square one pretty easy
i have a 1990 Johnson 8hp can i do the same with it?
nope don't even try my friend!
whar about the prop?Are they different pitch?
No, they didn't use different pitch; just let the 15 hp crank up to 6,000 RPM.
@@russg1801 they rev to 6500-7000! its funny if you don't let it rev, all that power is wasted. those 15's need to SCREAM!
where can I find a 15 hp carb for my 9.9 1990 evinrude
I usually find these on ebay. There's one for sale now you can find by searching "436991 evinrude" on ebay. It's a little pricey.
www.ebay.com/itm/Rebuilt-carburetor-for-15-HP-Johnson-or-Evinrude-outboard-motor-/111615281161?pt=Boat_Parts_Accessories_Gear&hash=item19fcca0809&vxp=mtr
I just sold one for a 1991 motor for $249 on eBay. Check completed items.
Pull your rewind it will cut your time in half and won't lose the nuts as bad
Just swapping carbs won't do it. You have to swap the reeds too.
and exhaust on 80' or 81' and up!
the 15hp has tune exhaust that the 9.9hp doesn't have your only getting maybe 12hp with just the carb
That was what I understood.. More than just a carb
Can you turn a 15hp into a 20hp?
Try nitro, turbo or supercharger or bigger cylinders
You dont have any carburetor used 15hp for sale
Are these the best engines for small boats ?
I have a 1974 evinrude 9.9 and its lost about 5 mph ever since I got it. We just got a new prop and it helped a little bit but not much. Any ideas?
Assuming you are observing the power loss at wide open throttle, you may need to clean out the carburetor - specifically the high speed jet. Often we will find buildup of debris or even complete blockage in the carburetor that may begin as symptoms of performance loss but may soon prevent the engine from running whatsoever. Take a look at the carburetor.
Might be your piston rings might be cracked😧 happens alot when you lose a load of compression like that you ccan tell if you remove the head and see if pistons have space between the wall or seem loose.
You're probably losing compression from a tired motor; either sticking rings or out-of-round cylinders. Time to retire it and find a newer 15 - save the old motor for parts - lower will swap on to motors at least through mid/late 1980's.
I can't for the life of me find a 15 hp carb for my 9.9
And the little holes in the foot its not ok
Way too late for heads up since I just came on this video but your impeller needs to be replaced definitely not pumping enough water to cool that motor down it's a very weak stream
You will get a bit more power from a 15hp carb but no where near as quick as a original 15hp.
Evinrude made a limited edition 10XP which is exactly the same as a 15hp but with a restrictor plate behind the carb to limit it to 10hp....remove that and you have a full 15hp.
Johnson also did the same, but I can't remember what they were labelled as...
They had so many 15hp and a lot of these engines needed to be 10hp or less for inland waterways in Europe / U.K so they just put the limiter plate behind the carb to reduce all the excess 15hp they had in stock!
Look in my videos....there's a Evinrude 10xp I sold a few years back...I still run one to this day and it will out do most newer 20 hp engines :-D
G.G Wilson i have a 1990 8hp Johnson can i do the same? and what would i need to do?
Just change the jet in a Mercury. 9 and 15 the same.
I have an 06 Mercury 8hp it weighs the exact same as the 9.9 I wonder what it would take to get me that 9.9hp or 15. Just curious if you might know what the difference is on the Mercury
HTS2000
The 15 hp has a bigger exhaust
My Evinrude 9.9 is a lot quieter than that one
you need to switch out the exhaust tube also. 9.9 and the 15 hp. are totally different. You will mess up your outboard otherwise.
That's an interesting recommendation, and we have a different opinion about it. In particular, both the 9.9 and 15 HP models use the exact same part number for their respective exhaust tubes. That part number is 0325333 or 0324048. If there is something we are missing, please let us know more.
highlandoutboards Paintballpro62 is correct. Some of the 15's also had a tuned exhaust which they say is supposed to add about 10% more HP at top end.
AMG If you can dig up a part number for the 15hp exhaust tube that should be used, that would be very helpful.
highlandoutboards But that could take days! :) Here's a great resource. About an eigth of the way down the page, they are discussed. www.leeroysramblings.com/Johnson%209.9_15.htm
Also, I am searching for a pull start assembly for a 1978 Evinrude 9.9. Any ideas where I can locate? Got one fore sale? Checked ebay and they're all for newer units.
I have a 9.9HP starter assembly for a 1982 model which appears to be slightly different than the 1978 by part diagram. Here's my ebay listing:
www.ebay.com/itm/121697642632?item=121697642632&viewitem=&vxp=mtr
You have not 15 hp because the pipe in 1983 its not ok for 15 hp
Did your wife know you're using her good china? Wish you would have tested motor before and after on the boat to test extra horses.
I’m going to put a 15 hp carb on my 2 hp and make 20 hp and put nitrous and put wings on my boat
There's no way just replacing the carb will add 6 horsepower
correct. the exhaust is the other big thing you need to change for most years, and i think the reeds and port timing is different on the 15hp.
Your chem dip melted you float bowl
You clearly didnt listen lol
All you had to do was seal the carb bowl with J B weld
what do you mean ?
Hate to tell you.but your wrong.the port timming is diff on the 15hp
FALSE ..... the exhaust was different too
For 1983
The 10 hp and 15 hp outboards have different heads!!! The 15 hp has much higher compression! Swapping just the carb won't do it! everything else is the same.... Ports, intake, .....
Not to be argumentative... but the 1983 15 HP and 10HP models have the exact same cylinder head (part# 0393529), same crankshaft (part# 0328224), same pistons (part# 0391990), and same exhaust tube (part# 0325333). The only difference is the carburetor.
I stand corrected. I was confussed with the pre 1977 heads that were issued from a recall. It turned a 15 hp into a 9.9 for gas shortage. Carry on.
concretereef the difference is in the exhaust pipe on the bottom of the head. To get 15 hp from the 9.9 you have to pull the power head and change the pipe
I thought something else was needed to fully upgrade it. Just changing the carb won't turn it into a 15hp. Thanks for the input.
Stop babbling so much