I just finished up the major components of my Yanmar 4JH80 installation and am extremely pleased with the results. I found Richard Carter’s and John Stevenson’s write-up very useful in planning for the swap.
I haven’t rebuilt the V-Drive or re-pitched the propeller yet. I’m currently able to hit ~3,050RPM (of a 3,200RPM redline) using the factory 20×13 propeller and 2:1 gear reduction. At that RPM, I am able to do about 8.4kts – quite a bit faster than the old motor! I will re-pitch and see if I can get it to match a desired RPM – I don’t think re-gearing is necessary.
I’ll try to put together a build document in the next few weeks with high resolution pictures for anyone else interested in undertaking the project. It took about 3 months to complete including planning and installation.
Attachments:

NewEngine.jpg

NewEngine2.jpg