User Tag List

Thanks Thanks:  0
Likes Likes:  0
Results 1 to 5 of 5
  1. #1
    Join Date
    Sep 2011
    Location
    daytona beach florida
    Posts
    3
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    1984 evinrude 70hp...need some guidance

    Hey guys,

    I came across a 1984 70 hp erinvude outboard. It came on a boat that I purchased. The motor is super clean with trim and tilt. I was wondering where I can get newer reeds or what carbs will change out with it to make a little more power. Not looking to go crazy but always wanting more.

    The boat is on a 17ft john boat. Also does anyone happen to know what throttles will work with this motor without alot of modifications? I also need a little guidance finding a new cowling as someone put metal air scoops in the one on the motor now.What were these people thinking?!

    Thanks guys! Love the website and have been lurking

    Will

  2. #2
    Join Date
    Sep 2011
    Location
    daytona beach florida
    Posts
    3
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Can someone move this to technical forum? My apologies

  3. #3
    Join Date
    Apr 2001
    Location
    Virginia Beach
    Posts
    3,254
    Thanks (Given)
    18
    Thanks (Received)
    13
    Likes (Given)
    56
    Likes (Received)
    112
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The 84 70-hp was an engine that was just about at the peak of it's lifecycle and development/refinement. This engine began life in 1968 as a 55-hp, then a 60 in 1970, a 65 in 1972, a 70 in 1974, and finally a 75 in 1975. The 70 received many refinements between 1974 and 1985 when it was last produced; the 1986 versions used a different powerhead (56ci vs. the 49.7ci version on your engine).

    If you're not racing it, the best thing to do is make sure it's tuned and set up properly. Of course the basic checks should be performed; compression and spark to begin, then the factory sync and linkage adjustments should be performed and adjusted if necessary. The fuel lines should be replaced with new ones to resist ethanol deterioration. A set of fiber reeds like those from Carson or similar will enhance idle and low end punch slightly, but really beyond that, any major changes you make to make power (shaving the head, porting, etc.) are not simple changes, are not cheap, and require a level of expertise. If it's just for fishing and fun, it's not worth it.


    John Tiger

  4. #4
    Join Date
    Sep 2011
    Location
    daytona beach florida
    Posts
    3
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Thanks john tiger. I had no idea there was a power head change. Pretty nice change as well. Some where I read about changing the carbs to 90 yamahas. Is this even possible?

  5. #5
    Join Date
    Aug 2009
    Location
    Southeast Texas
    Posts
    286
    Thanks (Given)
    0
    Thanks (Received)
    1
    Likes (Given)
    0
    Likes (Received)
    6
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I Don't know about the Yammy carbs, but the single most effective thing one can do to increase power on just about any of these 2 stroke motors is to shave the heads to increase compression. It is not complicated and should cost a couple of hundred dollars for the labor and a new set of gaskets. Find out from the OMC guys here how much to have the heads cut and still be able to safely run pump gas. If you can cut the heads a good bit you should get a lot more power from the motor. The carbs will need to be re-jetted after the heads are cut. Those old OMC three cyl motors were some of the best ever built IMO and can be made to run like a spotted ape
    Last edited by mastertrax; 03-04-2014 at 12:44 PM. Reason: Adding info

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
  •  
Frank Mole Transport