Mariner 4hp 2 stroke short shaft

[Tpenton]

Looking for any advice on if it possible to get a little bit more power out of engine it on a 3 m inflatable though of a big motor just they become to heavy i have no idear of the age

 

[VicS]

Its basically the same 102 cc engine as the 5 hp so up-rating might be possible. It might only be some simple changes such as removing a restrictor or changing carb jets or it may need changes that would make it non viable.

Studying and comparing the parts catalogues in detail might reveal the differences

 

[oldmanofthehills]

If you paid about £100 for it (and its worth little more than that) then paying lots of money for new and less restrictive carb makes little sense. If you can get one second hand that might be Ok but probably easier to buy a 5hp and sell your 4hp in the fullness of time

 

[peteK]

I had the 5hp version many years ago on a 19 ft Seawych,it may have been the main jet that was different but couldnt say for sure.

 

[Allan]

I had a 40hp Mariner of a similar vintage, which was in fact a Yamaha with different stickers. It may be worth checking to see if parts were shared with another manufacturer. Mariner, Mercury, Yamaha and others have all shared designs at some point.
Allan