Congratulations on finding a wonderful piece of 20th century engineering! These brass, bronze and cast iron monsters make a whopping three horse power at nine hundred RPM which was twice as much as the Evinrudes could make at the time! At least that’s what the ads said.

I would leave the Stihl oil on the shelf and use proper TCW III marine oil designed for outboard motors. My brochures don’t give the gas/oil ratio but like Steve said, someone will show up with the correct information. If you really want to start it, I don’t think I’d go any leaner than 16:1. 10:1 or even 8:1 would be safer for a first start. T2 (Chris Scratch) is the Koban Special Interest Group Leader in the AOMCI club and should have all the answers to your questions. Also, check out Jack Craib’s RBM site as there is lots of information there.

http://caille.8m.com/rowboat/index.html

http://caille.8m.com/rowboat/Koban/koban-index.html

http://www.antiqueoutboardmotor.info/Ou … 75-32.html

Here’s my newly acquired ’21 with magneto ignition as found which is apart right now waiting for a full restoration.

Bob Grubb’s Koban.

And a 1/8 scale model I found on the web.

One that recently sold at auction.

My avatar at the RBM club site.