User Tag List

Thanks Thanks:  0
Likes Likes:  0
Results 1 to 7 of 7
  1. #1
    Join Date
    Dec 2013
    Location
    Mississippi
    Posts
    3
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Putting bigger carbs on a 40 hp yamaha

    I have a 1989 yamaha 40 hp and I was thinking about putting bigger carbs on it. I was wondering if any of y'all could point me in the right direction on going about this. I'm some what new to this but I do have a little knowledge about outboards. I know I will need to redo the exhaust to make it run right but what else is there to it? And what year model carbs will bolt up to my motor? I was talking to a guy the other day and he said something about putting 70 hp carbs on it, can this be done or will it need a new head and everything for it to run right?

    Thanks!

  2. #2
    Join Date
    May 2011
    Location
    MN
    Posts
    31
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hydro Tech makes a tuner kit for that motor..

    there claims seem a bit high but worth looking into..

    http://www.shop.hydrotecmarine.com/p...2&categoryId=4

  3. #3
    Join Date
    Aug 2004
    Location
    Venice, Florida
    Posts
    9,535
    Thanks (Given)
    17
    Thanks (Received)
    96
    Likes (Given)
    344
    Likes (Received)
    650
    Mentioned
    0 Post(s)
    Tagged
    2 Thread(s)
    Can you mod the carbs you have? Is the throttle plate the smallest dia. of the bore.
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    I have a small Yamaha NOT a small Johnson

  4. #4
    Join Date
    Dec 2013
    Location
    Mississippi
    Posts
    3
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Mr. Demeanor View Post
    Can you mod the carbs you have? Is the throttle plate the smallest dia. of the bore.

    I could put larger jets in it I believe. But I don't know about the throttle plate

  5. #5
    Join Date
    Aug 2004
    Location
    Venice, Florida
    Posts
    9,535
    Thanks (Given)
    17
    Thanks (Received)
    96
    Likes (Given)
    344
    Likes (Received)
    650
    Mentioned
    0 Post(s)
    Tagged
    2 Thread(s)
    Just wondering if they can be bored. Mine are 34mm stock but the dia. at the butterfly is 39mm. The 34mm is ahead of the butterfly choking it down. We bored them to 36mm and did some mods to the throttle shaft reducing its profile. Picked up 150-200rpm on my modded Yamaha 130.
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    I have a small Yamaha NOT a small Johnson

  6. #6
    Join Date
    Sep 2002
    Location
    Parry Sound, On
    Posts
    2,168
    Thanks (Given)
    4
    Thanks (Received)
    6
    Likes (Given)
    62
    Likes (Received)
    42
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    70 carbs are a big bore version of the 40/50 carb...otherwise they are pretty much identical. To see any real performance gains you will need to change the tuner. The 40 tuner is very restrictive so you'll need the pro50 tuner at the very least.

    You can change the tuner and I think jetting and make it a 50 pretty easily.
    '08 SRV
    Yamaha 3.1 Phase III


  7. #7
    Join Date
    Dec 2013
    Location
    Mississippi
    Posts
    3
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by DoktorC View Post
    70 carbs are a big bore version of the 40/50 carb...otherwise they are pretty much identical. To see any real performance gains you will need to change the tuner. The 40 tuner is very restrictive so you'll need the pro50 tuner at the very least.

    You can change the tuner and I think jetting and make it a 50 pretty easily.

    What year model carbs will bolt straight up to my motor? And what do you think the best tuner would be?

Tags for this Thread

Posting Permissions

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