At least in the Tropics, outboarders are beside dinghies one of the most important items on board.

In principle one divides between 2-stroke and 4-stroke outboarders.

A 4-stroke produces less pollution than 2-stroke. But having the same amount of power will weigh about double. And a 4-stroke is much more complicated in construction and therefore requires much more service. From that point of view the small 4-stroke (up to approx. 30 HP) are a bad alternative to a 2-stroke, if you are in the field and far from good workshops. Therefore, especially in the Tropics, more and more 4-stroke are exchanged back into the more simple and more reliable 2-stroke. This did not remain hidden for the industry. The manufacturers work intensively on more pollution free 2-stroke. Until then they are selling their 2-strokes into countries where 2-strokes are not banned - from good reasons.

Until approximately 2010 Yamaha 2-stroke (Enduro) outboards up to approx. 25 HP were told to be particularly good and reliable. One could run them with small maintenance costs 15 years and more.

But those who bought these Yamahas after 2010 might have had lot worse experiences:

The former very reliable engine will stand usually only one season in a good shape. If it is stored thereafter for 4 months or more up to the next season (typical for the Caribbean or other tropical areas), the drive shafts between engine head and transmission will be seized in their shaft tubes. The engine is blocked thereby and the prop is not moveable any more, even if using force. For a repair the engine head and the engine foot must be separated. Even that requires most brutal force. Here always heavy damage to the engine mount arises and usually also damage in the transmission is to be expected.

Yamaha mechanics explain that in such a way:

The drive shafts between engine head and transmission are neither sealed against sea water nor has maintenance-free bearings. They are (as to be new engines!!!) not even greased. Therefore new engines should be divided and their drive shafts have - at least - to be greased before using the engine the first time. Otherwise they will be seized after short time for sure and must be completely divided and repaired very expensively. But no one does that because no one will expect such a bug inside the engine. And Yamaha does not inform their customers about that unexpected bad engine construction. A respectable manufacturer would recall and would repair all such engines free of charge. Regularly the defect will occur as soon as the 1 year warranty is over.

Especially the Yamaha 10 HP and 15 HP Enduro engines are particularly bad in this regard. Such damage will arise on nearly every engine that was stored for some months and was not used every day. A Yamaha dealer in the Caribbean reports: Often 3 or 4 of those 15 HP Enduro engines come into his workshop per week because of exactly this damage. Mostly when winter saison starts and those engines had been stored during summer.

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