Mariner 4hp 6E0 outboard issues

[M4568]

I have a mariner 4hp 6E0 outboard which I bought to replace my 2.5 fourstroke on my 2.7 air deck.

It seems as though the engine is holding back on power, I have stripped and cleaned the carb replaced the spark plug and it seems to be the same.

the engine does run absolutely fine and idles perfect its just my 2.5 fourstroke is faster than the 4hp 2 stroke which I don't think should be the case even my friends 2hp Suzuki and 2.5 mariner 2 stroke are faster.

Is there any obvious reason as to why this may be the case my next step was going to be changing the propeller.

 

[gordmac]

Does it appear to reach max revs? Same length?

 

[M4568]

I’m not to sure what full revs is supposed to sound like on the 4hp, I’ve watched YouTube videos and it seems they are reving a lot more on there.

It Also seems to rev a lot higher in the reverse gear and acceleration in reverse seems a lot quicker.