Results 1 to 6 of 6

Thread: Tohatsu 50 mods

  1. #1
    Team Member Roflhat's Avatar
    Join Date
    Jul 2011
    Location
    Scotland
    Posts
    166
    Post Thanks / Like

    Default Tohatsu 50 mods

    Planning some mods this summer, got Yamaha 70 carbs to go on, need to open up the reed block for them too. Got a Mikuni fuel pump to put on as well which is hopefully more reliable than the standard tohatsu one.
    Was going to modify the exhaust tuner as well, open it up a bit and cut 25mm off the end. Has anyone else done this? How do you get to the exhaust tuner?

    I read online that the flywheel ring gear can be removed so going to look into that. Or if not then maybe lighten the flywheel.

    also if anyone knows roughly a big a job it is removing the crank, welding it and putting it back in? how many hours/days, just so I know what to expect.

    Cheers

  2. #2
    Team Member Roflhat's Avatar
    Join Date
    Jul 2011
    Location
    Scotland
    Posts
    166
    Post Thanks / Like

    Default

    Apparently the easiest way to open the exhaust is just to buy a D1 tuner, anyone know the part no. for these? Can I get one new from a tohatsu dealer?

    Also I've been told I can take the engine apart, weld the crank and get it back together in a day! sounds like a challenge...
    Is this the only place I need to weld the crank? Like in these photos:
    Name:  photo 2-4.JPG
Views: 1501
Size:  59.4 KB
    Name:  photo 1-4.JPG
Views: 1377
Size:  149.3 KB

    Is there anything else I should do while the engine is apart?

    Thanks,
    Seumas

  3. #3
    Team Member Roflhat's Avatar
    Join Date
    Jul 2011
    Location
    Scotland
    Posts
    166
    Post Thanks / Like

    Default

    Apparently taking 1mm off the head raises the compression by 30psi, so if I take 0.5mm does that mean it will raise by 15psi? Or is there more to it than that?

  4. #4
    Team Member
    Join Date
    Oct 2022
    Location
    Lake Charles, LA
    Posts
    1
    Post Thanks / Like

    Default

    Quote Originally Posted by Roflhat View Post
    Apparently taking 1mm off the head raises the compression by 30psi, so if I take 0.5mm does that mean it will raise by 15psi? Or is there more to it than that?
    I’m a day late and a few dollars short but did you ever figure any of this info out? I am looking to modify my M40D2 with some similar mods. The next thing on the list is flywheel work and shaving the head to get 150 lbs out of it.

    Best,
    Avalon

  5. #5
    Team Member DeanFHobart's Avatar
    Join Date
    Feb 2005
    Location
    Lake Sammamish, Washington and Indio, California
    Posts
    189
    Post Thanks / Like

    Default

    Quote Originally Posted by Roflhat View Post
    Apparently taking 1mm off the head raises the compression by 30psi, so if I take 0.5mm does that mean it will raise by 15psi? Or is there more to it than that?
    Ask on this site and on hydroracer.net…. Who is the guy that makes the racing tower house and gear case for racing. He lives in the eastern part of the US….I think he advertises in the APBA Propeller magazine. I’m sure he can help you.
    Dean Hobart

  6. #6
    Team Member Roflhat's Avatar
    Join Date
    Jul 2011
    Location
    Scotland
    Posts
    166
    Post Thanks / Like

    Default

    Yeh I shaved 1mm from the head which gave 30psi more. Eventually put a TSR head on it which was slightly better again, along with the D1 exhaust. I've got the whole thing quite well documented here - https://www.rib.net/forum/f50/my-thu...-61912-30.html
    Thanks hydrospeed77 thanked for this post
    Likes slowJEEP liked this post

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Replies: 3
    Last Post: 01-29-2012, 08:23 PM
  2. Gen iv 45 mods
    By OUTBOARDER in forum Technical Discussion
    Replies: 2
    Last Post: 12-18-2011, 05:03 PM
  3. 45 ci MODS
    By thornl01 in forum Technical Discussion
    Replies: 12
    Last Post: 10-05-2009, 06:04 AM
  4. 25 OMC Mods
    By 88workcar in forum Technical Discussion
    Replies: 18
    Last Post: 08-17-2009, 06:06 AM

Bookmarks

Posting Permissions

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