4hp jerky power loss

Hi all i hope somebody can help i'm having some problems with my yam 4ac i use it on a 2.7 mtr sib my problem is sometimes it will plane and sometimes it wont i was out with my girl at the weekend and it felt very jerky power wise every now and again you could feel it jump i dont know if it has anything to do with it but when it goes in reverse the whole thing jumps quite aggressively which surely isn't right when it does get to plane it takes forever before you hear it liven up abit and start it's as if it's got no guts past 1/2 - 3/4 throttle please help a HUGE THANKS in advance.
Paul

sounds like the carb is gummed up

check for spark on both cylinders

Thanks for that i had a funny feeling it could be but being new to outboards wasn't sure my daughters quad was very similar what is the best way to deal with these carbs? do i need to strip it down or can i use a carb cleaner through the throat whilst it's running? like the quad.

you can try some seafoam

but there is no such thing as a mechanic in a can