How To Turn A 1976 9.9hp Johnson To A 15hp(Carb Exchange)




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How to turn a 1976 9.9hp Johnson to a 15hp(Carb Exchange)
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1974 Johnson 9.9hp outboard motor
1974 Johnson 9.9hp outboard motor
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1975 Evinrude 9.9hp with a 15hp carb
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Johnson 9.9hp outboard running in test tank. New water pump installed.
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MetalTeamster: exhaust was diff on 15s....´╗┐

chargerkid2011: Is this motor pretty reliable? Im getting ready to purchase the same motor´╗┐

troyusaguy: I have the exact same motor. I was inspired by this video and bought the 15hp carb. I cant wait to try it, hopefully my buddy can come over and swap the carb. Ill keep you posted. How do you like these older motors? Ive thought about buying a newer one, 4 stroke, but this way seemed to fit my immediate budget.

Tater79bj: Nice vid, but your only half right with the carb change. Hp gains are built into the block itself via porting. The 9.9 and 15 blocks may be indentical, but I bet money the exhaust ports on the 15 are bigger. You may gain a little with the swap, but not the full 15. Its like 2 to 4 barrel swap on a v8.

bsrktm1: In 1976, the ONLY difference between a 9.9 and 15 was the carb. It has a larger venturi and bigger jets than the 9.9. The 9.9 is a restricted 15. Later models added the tuned exhaust to get a full 15 prop rated Hp. Early (before about 1980) models were flywheel rated.

aussiepaul49: The 9.9 uses the same power head, exhaust housing and reed plate. All those items use the same OMC part numbers. There is no difference. I've just replaced a broken reed on a 1982 15 hp using the reed out of a 1979 9.9 and I can tell you they are exactly the same.

BOATSandAIRSOFT: Well I found my carb on eBay so I suggest looking around on eBay for one and I went to my local dealer and asked if he had any 15hp Johnson carbs and he said that they have not sold a carb brand new since 1976 when the motor was changed so I suggest to look around on eBay

bob o: is this a 2 stroke

mjtj456: This kid is an idiot....Changing the jets or the carburetor on a 9.9 hp Johnson won't turn it into a 15hp engine...The engine will run slightly faster, but the exhaust ports are larger on a 15hp engine and you definitely will not be achieving a 15hp rating or anything even close....

BOATSandAIRSOFT: @1MACVSOG1 you should take of you lower unit and make sure that the shifit rod and linkage are in proparly anf if not lossen one of the screws on the linkage and slide the shift rod down untill it is fully in place

Ferdinand den Bleker: awsome! Do you think I can do the same with my 9,9 hp from 1975, and my 15 hp from 1976? Someone gave me the 15 hp but I'm not sure if I can get it fixed so I was thinking about switching the carb. Is there really nothing else you have to change? Not even the exhaust or the ignition? greatings from Ferdinand (from the Netherlands)

iCloud: changing your carb wont make it 15 hp it will give you more torque and maybe 1 hp extra but over time it will wear and just act like the stock carb if you want to add more power just go buy some freaking nos or a bigger freaking engine:S

craig irvin: Hi there, that vid was pretty helpful! i have the same model as that and i'm haven a nightmare of a time tryin to find a 15hp carb, any recommendations?

96Duelfuel: In another video, the fellow changing the carb took off the starter, and cautioned everyone, that when unscrewing the starter bolt and wrapping tape around it, to use extreme caution, as the spring is under quite heavy load and fly out and hit you (i.e. your eye). This is a very important piece of information.

MrPequod1: Be aware that this is not the only difference in the 9.9 and 15. I did the swap on the same engine. I didn't gain much. The exhaust housing is bigger on the 15 and the leaf valves also need a shim to open them up. In order to do that ,you need to take the block out. I have done that, and It is not advised unless you have some prior outboard motor experience.

BOATSandAIRSOFT: @SouthernCross33 you should look on the side of your motor there should be alittle plate that has numbers on it the one that says serial number look at the last two numbers and that should show you how old your motor is so for example ********88 means that the motor is an 1988 or what you can do is be more specific instead of looking at the last two numbers type in the whole serial number in the internat and type in behind it johnson serial number

orignalbuckaroo: I think you're right, beside, the 76 still had points and condenser!! Electronic started in 77, then we started to have real prop horse power which made a huge difference in the speed !! TNX for the comment!! :)

dana woolaver: i just got one of these... here is a stupid question is this motor a 2 or 4 stroke???

ArnzT100: Any young person who can change out a carb on an old 'Rude has a lot on the ball. Let's be more encouraging toward a kid who knows more about 2-cycle carburetors than your average adult. He's going to be an awsome mechanic.

1kruzer1: mjtj456, I suggest you check your facts before you stoop to name calling. In 1976 the ONLY difference between the 9.9 and 15 is the carb. No difference in ports, no difference in exhaust tube (tube change came later when they switched to prop shaft rating), and no difference in reed assembly. Change the carb and, if it doesn't quite rev to the 15HP factory RPM spec, change the prop so it revs between 5500 and 6000, and PRESTO you have the identical engine as the factory 15.

iCloud: @BOATSandAIRSOFT erm let me see you goto you local car tuning shop you buy a nos kit and you get a marine adaptor for the engine and the solenoid power for everything etc hook it all up start engine open the tank of nos to let the gas flow hit the button and away you go ?

jaden crochet: Great video and where did you get the 15hp carb?

bsrktm1: I'll take the bet and your money. A 9.9 is a restricted 15. Same block, crank, rods, porting, compression, reed block- Does it make sense from a manufacturing standpoint to change all that? Carb IS THE ONLY difference in 1976. Reed shims (they add VIRTUALLY no Hp), and tuned exhaust were added to later 15s to get a full 15 PROP horsepower. 15s also were rated at 1000 higher RPM.

BOATSandAIRSOFT: ebay

1MACVSOG1: hey buddy I was wandering you could help me I just pick up the same motor for 50 $ it runs great all for 1 thing when you get going full throttle under about 600lbs load "boat and me in it" it wants to jump out of forward ?? Back into neutral I can hold in in forward and it will run fine was wondering if ya knew? What the problem was

Fauerbachbrewery: good work and good camera work. Helpful information!

neo71665: Difference in the exhaust also. The carb swap is a big part of the difference but its not the only one. You might have made it a 11 or 12 horse.

orignalbuckaroo: Nope, not only the carb !! To do this job correctly, he needs to change the exaust tube as well, if not, the engines wont have full performance and it will be darn hard on gas !!!

BOATSandAIRSOFT: Yup

wiliam sullivan: Great job. Laugh at the negative comments. Talkers are always talking about doers.

putsstuff: He is not an idiot he is right the 2 blocks are identical only the carb was the difference

Jelmer Gunnink: Is it the same thing if you have a electric start?

BOATSandAIRSOFT: @Troyusaguyi love these type of motors the are very reliable and are great runners I have recent lye sold this mototr and upgraded to a little bit newer one a 1988 9.9 Johnson and I lone it now I would love to keep on hereing about you boat motor

bsrktm1: @daervs100 15hp OMC carbs from 1974 to 1992 are interchangeable. Newer (mid 80's) are plastic on top and bowl. Keep in mind that many people don't know the differences between the 9.9/15 carb since they look externally the same- it's the venturi area that is the difference. Check Craigslist in your area. I've bought several complete non-running 15hp motors for 100-150$. 15hp carbs on Ebay can be that much alone. You'll have lots of spare parts- BTW- I've bought 9.9's that had a15hp carb already.

leon karras: exw mia johnson 9-9hp toy 1984 mporw na th kanw 15 mono me ydatanthrakes h tha xreiastw k exatmish??????

BOATSandAIRSOFT: Yes the gear ratios are different in the lower unit back in 1976 the measured the horse power by the power head now after they 1976 they started measuring the lower unit horse power at the bottom end

christoph1039: Good job man. Say thanks to your crony there too for the good recording. Thanks for the clear steps. Used this video to clean the carb on my 1981 15 johnson.

SouthernCross33: Hello, can you tell me how to find the date of my 15 hp johno. I bought a 25 hp suzuki motor to push my old glass boat along quicker but have found i can't tell which is quicker. I prefer the johno though
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How to turn a 1976 9.9hp Johnson to a 15hp(Carb Exchange)