Hi all,

New to the site, love the info I have found so far.

I have a Nissan(tohatsu) NS40D2 tiller on a 16 foot shallow v aluminum boat. It probably weighs 400-450lbs. the cavitation plate is about even to a 1/2 inch below the bottom of the hull. So far I have confirmed the stock timing settings and have adjusted the top carb throttle stop to allow the carbs to fully open (they were only opening about 2/3 stock).

The motor runs well and has great bottom end power and mid range but seems a little flat on the top end.

I have ran the stock 12.5 pitch large ear prop (little rake) and a 14 pitch mercury prop which was smaller diameter with more rake. The raked prop porpoised more and would not take as much trim.

Top speed with 1000 lb load and empty was within 3 MPH (27 vs. 30 MPH) with both props.

RPM's are unknown at this time (in process to install a tach) but the motor did not seem to be lugged.

Empty top speed was somewhat limited by porpoising.

To increase top speed do I need to?

1) Take the reeds off the motor and set the reed stops to to 50Hp specs
2) Adjust the timing to 50 specs (I adjusted the timing up 1 degree an it slowed 1 mph (18 to 19 degrees) I set the timing 1 degree down and is seemed to smooth out the upper midrange and gave me my 1 MPH back)
3) Determine if I am bumping the rev limiter (when does it start coming in? is it a hard or soft rev limiter)
4) Put larger carbs on the motor
5) Look into a semi clever prop to give me some stern lift and settle the boat down and allow the trim to be more neutral (empty the boat still porpoises wthe the motor all the way down)

Thanks in advance

Mark