Here is the thread on building a super motor
http://www.boatracingfacts.com/forums/s ... hp?t=13663Here is the motor you start with..LOOKS MINT!!
http://www.ebay.co.uk/itm/YAMAHA-60hp-S ... 1c25e886e6The Motor
In the states it was the Mariner 48, 55 and 60 hp, 2 cylinder, 15 inch, 1.84 or 1.71 gearcase, Yamaha made.
In Mexico and Canada it was the Enduro or Yamaha brand.
The motor was sold world wide as a commercial motor. Very sound and well build.
You can still get new parts thru Canada and Mexico.
Unlike the 70 hp Yamaha this motor has a solid steel crank, bolt on rods, twin carbs and a unique double exit exhaust system.
You can get Boyensen reeds for them.
You can use a 70 or 90 hp factory power trim on the long shaft version.
You can use Pro 50 power trim on the short shaft version
You can use the old in-line 4 and 6 cylinder Mercury power trim on either version
Stock Performance
We have only had one to try. It was a 55 hp Mariner long shaft. On a Delta and a VooDoo
high 50's with NO MODS at all.
What you should be able to get MOD
80 to 90 hp
Cylinder head MOD
There are one or two people on this site that can make small chamber heads for these. Being a commercial motor, the head is not a performance head. A performance head will make a big difference.
The Crank
Unlike the OMC 45 cubic inch crank which weakens after being reworked, this crank does not. It can be stroked to perfect spec and blue printed.
The Exhaust Chambers
I am sure someone will come up with some performance ideas for them.
Cost
Lots of low cost stuff out there, good bang for the buck.
