Re: MERC 25 same as Nissan/Tohatsu?
It sure can get confusing, especially as we (the consumer) don't get all the facts upfront. It's the same in the car industry. Badge loyalty means very little these days.
Until 2006, Suzuki manufactured the Johnson four strokes up to 225 HP.
For 2006 Suzuki only makes the Johnson four strokes up through 30 HP, Evinrude produces direct injected two strokes (E-Tec) 40 HP and above.
Nissan outboards are built by Tohatsu.
Honda three cylinder powerheads were mounted on Mercury drive legs and props. For the last several years, Honda has built its full line of outboards.
Mercury four strokes from 2.5 through 30 HP are built by Tohatsu.
Before Yamaha entered the U.S. Market, Mercury's Mariner line was built by Yamaha.
2005 Mercury four stroke powerheads from 25 through 225 HP (except the Verados) were built by Yamaha. Several of those models used Mercury drive legs, electronics and EFI systems (replacing carbs Yamaha used in similar sized engines).
In 2006 models, Mercury four stroke powerheads from 40 to 225 HP (except the Verados) are built by Yamaha.
Mercury's agreement with Yamaha ended (badly) in March 2006.