Rebuilding and generally sprucing up the the Yanmar 2GM20F.
First some useful links about this little gem.
http://yanmarhelp.com/s_tach.htm
http://www.bluewatershipsstore.com/Engines/yanmarpartsnumber.aspx
And here is a nice pic of dipstick side of the engine courtesy of Yanmar.
- Yanmar 2gm20f

