Logo
Results 1 to 28 of 28
  1. #1

    Default 9.9HP conversion to 15HP

    Hello I just purchased a 1979 I believe to be a 9.9, the owner states it has a 15HP carburetor the serial plate is missing but the serial number on the block matchs a 9.9 how can I tell if this is true. the carb number to the best I can read is 388275.

    Thanks Bob

  2. #2

    Default Re: 9.9HP conversion to 15HP

    also with 388275 if it fits both 9.9 and 15 HP, what do I need to get it back to 9.9 specifications, and how can I tell what engine size it came off of in the first place.

    Thanks Bob

  3. #3
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    5,049

    Default Re: 9.9HP conversion to 15HP

    The high speed jet will give you a clue. The 15hp also has a spacer between the reeds and reed stops.
    Last edited by kimcrwbr1; 02-14-2016 at 06:42 PM.

  4. #4
    Join Date
    May 2015
    Posts
    2,451

    Default Re: 9.9HP conversion to 15HP

    The only thing that will tell you what carb you have is the size of the throat. The 15 hp and 9.9 do not use the same carb the 9.9 has a much smaller throat than the 15 carb. There are no reed spacers on that year 15 hp. Evinrude makes it confusing by making the part # the same on the parts fiche for both carbs. Up until about 1980 they are the same motor except for the carb. Try to take a pick of the throat of the carb or I have one of each I will try to post a pic tomorrow.

  5. #5

    Default Re: 9.9HP conversion to 15HP

    thanks I would like to keep it a 9.9 but I don't know exactly what carb is on it, the block is a 9.9. do I need to remove the carb to check the carb or can it be done on the engine.

    Thanks Bob

  6. #6
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    5,049

    Default Re: 9.9HP conversion to 15HP

    The 9.9 and 15hp motors are exactly the same other than carb venturi. 9.9 is 5000 rpms and 15hp is 6000 rpms. Keep it under 5000 rpms and enjoy your time on the water

  7. #7
    Join Date
    May 2015
    Posts
    2,451

    Default Re: 9.9HP conversion to 15HP

    I agree leave it alone and have fun

  8. #8

    Default Re: 9.9HP conversion to 15HP

    what if when I rebuild the carb if it is a 15HP carb if I was to change the metering jet in the carb back to the 9.9 size, only leaving the orifice larger. I really don't want to blow this engine up

    Thanks Bob

  9. #9
    Join Date
    May 2015
    Posts
    2,451

    Default Re: 9.9HP conversion to 15HP

    You can't do that the jetting needs to stay with the carb. Those 9.9/15 motors are exactly the same except for the carb. I guess I don't understand why you are so worried about the change.

  10. #10

    Default Re: 9.9HP conversion to 15HP

    well the jet inside is a #56 and the opening of the carb to the block side is 1" and the orifice inside is .875 sounds as if it is a 15 HP carb. I was wondering if what the guy I bought it from was telling the truth. the serial plate on the frame is missing, but the serial number on the block matchs a 1978 9.9 the engine cover is painted over, he said it was a 15HP when I went to look at it and noticed it was a 9.9, so that's why I was wondering if it was a 15HP carb or a 9.9HP

    and after removing the carb underneath I founded on the float bowl screws a small tag with numbers #391654
    MX
    04 B K

    what do you think a 15HP carb

    Thanks Bob

  11. #11
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    5,049

    Default Re: 9.9HP conversion to 15HP

    If it aint broke dont fix it!

  12. #12

    Default Re: 9.9HP conversion to 15HP

    that's just it it is broke I bought is as a basket case in parts but its very ez to put back together I am just trying to find out about the carb because 15HP models have shims under the head, and the exhaust is different also from the 9.9, but what tru the wrench in the mix is that the 9.9 and the 15HP have the same carb numbers but have different size orifice, and main jet size different. I didn't want to pull the recoiler, and carb to find out I thought one of you guys could tell buy looking at the outside of the carb this engine was taken apart buy another person and I have to put her back I like to get another 9.9 carb and keep her original.

    Thanks Bob

  13. #13
    Join Date
    May 2015
    Posts
    2,451

    Default Re: 9.9HP conversion to 15HP

    Here are the picsClick image for larger version. 

Name:	S4010314.jpg 
Views:	628 
Size:	28.0 KB 
ID:	12794Click image for larger version. 

Name:	S4010314.jpg 
Views:	628 
Size:	28.0 KB 
ID:	12794Click image for larger version. 

Name:	S4010315.jpg 
Views:	210 
Size:	29.8 KB 
ID:	12795Click image for larger version. 

Name:	S4010316.jpg 
Views:	278 
Size:	28.5 KB 
ID:	12796
    2 on the left are 9.9 2 on the right are 15 hp both these carbs are off of 79/77 motors. If you notice the 15 hp carb does not have the brass tube running through the middle and you can tell the 9.9 carb is much smaller. Sorry they are not the best pics but they show the difference. Bob the 79 15 hp does not have the exhaust tuner or the shims uses the same exhaust tuner on both 9.9/15 hp those improvements came later.
    Last edited by flyingscott; 02-15-2016 at 03:30 PM.

  14. #14
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    5,049

    Default Re: 9.9HP conversion to 15HP

    What all have you done to the motor? Normally you would have scored cylinders and possible bad bearings and burnt pistons if it was running too lean. Maybe start a new thread and take us through the rebuild the carb is the very last thing. Kinna hard to determine what jet goes to what carb. From what I see you have two choices stock .056 and .058. Jet size would also be relevant to altitude if your running high altitudes use the smaller jet size. The carb number you gave came in early to mid 80s motors.

  15. #15

    Default Re: 9.9HP conversion to 15HP

    ok kim here is what we have I purchased a 1979 so called 15HP, did a compression test and was good, spark test in both cylinders good, lower unit failed a vacuum test will need seals and a new water pump, plus the electric starter is shot, so knowing all this I now wanted to know if the man I bought it from said it had a 15HP carburetor, to be shur I started to do some research and got totally lost with the numbers because both engines use the same numbers.
    Now explain how can 2 carbs with different size orifices have he same numbers totally different molds they had to come from & the missing brass tube in the picture.
    so I know it is definitely I have 9.9HP with a 15HP carb. Thanks to all you guys your help was great all the other forums just didn't have the knowledge you have

    Thanks Bob

  16. #16
    Join Date
    May 2015
    Posts
    2,451

    Default Re: 9.9HP conversion to 15HP

    Evinrude doesn't want it converted that's why they do the part# numbers like that. Ever wonder why it's called a 9.9 not a 10 like the disc on the powerhead says. It's because the 9.9 can be used on lakes with 10 hp restrictions Evinrude did not want it to be converted to 15 hp easily and make it illegal.. And I bet your carb is fine the conversion is easy so i bet you have the original jets in the carb that you need. When you buy the 15 hp carb for a 9.9 you just clean it up and put it on no parts need to be changed.

  17. #17
    Join Date
    Dec 2015
    Location
    maplevalley WA
    Posts
    5,049

    Default Re: 9.9HP conversion to 15HP

    http://www.seawaymarine.com/
    Give these guys a call they have the best books. Give them the carb number and they will be able to tell you if its a 15hp carb and proper jet size. Part number 0391654
    Last edited by kimcrwbr1; 02-15-2016 at 06:05 PM.

  18. #18

    Default Re: 9.9HP conversion to 15HP

    Kim & Scott I thank you both but I have figured out that the carb on the engine that is a 9.9HP, is clearly a 15HP carburetor. it has the larger #56 jet, and has the larger orifice .875, and has the brass tube only 1/2 the throat, and last but not least has the #391654 on a alummium tab on the bottom of the float bowl. you couldn't see the 391654 number, or measure the orifice, and see the brass tube unless you removed the carburetor. now that is over now its time to get to putting her all back together. thanks for all your help.

    Thanks Bob

  19. #19
    Join Date
    Jan 2021
    Location
    Lake Oconee/ Greensboro Georgia
    Posts
    4

    Default Re: 9.9HP conversion to 15HP

    Quote Originally Posted by flyingscott View Post
    Evinrude doesn't want it converted that's why they do the part# numbers like that. Ever wonder why it's called a 9.9 not a 10 like the disc on the powerhead says. It's because the 9.9 can be used on lakes with 10 hp restrictions Evinrude did not want it to be converted to 15 hp easily and make it illegal.. And I bet your carb is fine the conversion is easy so i bet you have the original jets in the carb that you need. When you buy the 15 hp carb for a 9.9 you just clean it up and put it on no parts need to be changed.

    That last sentence in your above reply about the 9
    9 carb accepting a 15hp carb, no parts needed and all u gotta do is clean it up, is wrong. They don't fit, nowhere close. I have both in front of me. I saw this before I purchased mine, thinking you were prob saying it cause you did it and it worked. Cost me $150 bucks and wasted time. Please don't post things unless they are true or say you don't know for sure. Thats all. Hope this helps.

  20. #20
    Join Date
    May 2015
    Posts
    2,451

    Default Re: 9.9HP conversion to 15HP

    Quote Originally Posted by FishingNutz View Post
    That last sentence in your above reply about the 9
    9 carb accepting a 15hp carb, no parts needed and all u gotta do is clean it up, is wrong. They don't fit, nowhere close. I have both in front of me. I saw this before I purchased mine, thinking you were prob saying it cause you did it and it worked. Cost me $150 bucks and wasted time. Please don't post things unless they are true or say you don't know for sure. Thats all. Hope this helps.
    You are wrong. 9.9 / 15 hp carbs 74-92 are direct replacements for each other. Figure out what carbs you have and dont resurrect old posts. I have made that conversion more times than I can count. Start your own post and put pics up of those carbs.
    Last edited by flyingscott; 01-12-2021 at 10:20 PM.

  21. #21
    Join Date
    Jan 2021
    Location
    Lake Oconee/ Greensboro Georgia
    Posts
    4

    Default Re: 9.9HP conversion to 15HP

    I guess I didn't see the years posted. I have a much newer model than that. I guess every year after that doesn't fit. I have a 97... serial number starts with 254.... they don't fit each other. I tried to post a pic to back me up. I guess it wasn't uploaded.

  22. #22
    Join Date
    Sep 2010
    Posts
    21,163

    Default Re: 9.9HP conversion to 15HP

    9.9 and 15 HP carburetors mount the same.----You need to figure out what carburetor you got for your $150 I say.---Any pictures ?

  23. #23
    Join Date
    Sep 2010
    Posts
    21,163

    Default Re: 9.9HP conversion to 15HP

    9.9 and 15 HP carburetors mount the same for 1974 to 1992.------The 1993 and newer were a bigger displacement engine.----You need to figure out what carburetor you got for your $150 I say.---Any pictures ?

  24. #24
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    4,064

    Default Re: 9.9HP conversion to 15HP

    FishingNutz bought the newer carb......different animal.

  25. #25
    Join Date
    May 2015
    Posts
    2,451

    Default Re: 9.9HP conversion to 15HP

    The new poster on this 5 yr old post has a 97 model. I believe te carbs still interchange on the 2 strk model motors. Wondering if he got a 4 strk carb. Start your own post with pics.

  26. #26
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    4,064

    Default Re: 9.9HP conversion to 15HP

    Yes...he could have got a 4 stroke carb.

  27. #27
    Join Date
    Jan 2021
    Location
    Lake Oconee/ Greensboro Georgia
    Posts
    4

    Default Re: 9.9HP conversion to 15HP

    Quote Originally Posted by timguy View Post
    FishingNutz bought the newer carb......different animal.

    Yes totally different animal. Nowhere close to mounting up. I suppose it has to be the newer model as the other fellas have done the swap. I was unlucky in doing so, as inhadnt ever seen any posts regarding the years and so on. Now we all know. Only thing is most people by the time they sell the carb, they don't know what year it.came off of etc. Some do, not all tho. Good post and hope I didn't step on any toes and were all good. Yall take it easy, happy fishing and boating!! Jonah


    Also , i do have a 2 stroke 97 model. If I knew how to post pics I would. It keeps uploading but must not be same format. I tried iPhone 11 and note 10. Neither did. Tried. Sorry

  28. #28
    Join Date
    May 2015
    Posts
    2,451

    Default Re: 9.9HP conversion to 15HP

    Quote Originally Posted by FishingNutz View Post
    Yes totally different animal. Nowhere close to mounting up. I suppose it has to be the newer model as the other fellas have done the swap. I was unlucky in doing so, as inhadnt ever seen any posts regarding the years and so on. Now we all know. Only thing is most people by the time they sell the carb, they don't know what year it.came off of etc. Some do, not all tho. Good post and hope I didn't step on any toes and were all good. Yall take it easy, happy fishing and boating!! Jonah


    Also , i do have a 2 stroke 97 model. If I knew how to post pics I would. It keeps uploading but must not be same format. I tried iPhone 11 and note 10. Neither did. Tried. Sorry
    Start your own post. Are you sure you did not buy a 4 strk carb? The 2 strk carbs should be almost identical.

Similar Threads

  1. 1999 Mercury 15HP 2-Stroke Electric Start Conversion
    By Mitch Higgins in forum Mercury Mariner Outboard Forum
    Replies: 10
    Last Post: 12-16-2015, 01:07 AM
  2. Tohatsu 9.8HP conversion to 15HP?
    By doxmit in forum Nissan Tohatsu Outboard Forum
    Replies: 5
    Last Post: 08-03-2014, 11:37 PM
  3. Replies: 2
    Last Post: 03-15-2011, 12:52 AM
  4. 99hp Mariner 2 stroke 2001 Conversion to a 15hp
    By backhoe_bob in forum Mercury Mariner Outboard Archive
    Replies: 4
    Last Post: 04-17-2009, 04:45 AM
  5. Johnson 15hp longshaft to short conversion
    By J Gable in forum Johnson Evinrude Outboard Archive
    Replies: 0
    Last Post: 03-10-2006, 01:40 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •