1967 Merc 500 possible fuel issue?????

[14thunderhawk]

Hey there im new to the website and the forum and am looking for a helping hand on a project thats almost done. I got a 14ft retro thunderhawk tri-hull and had to cut the transom out a little for this merc 50hp to fit and now that it works and shoots out of the water like a rocket i cant seem to get the top end full throttle to go all the way. When its maxed out or nearly maxed out then the dang thing starts to hesitiate and it wont stay nice and smooth when full throttled. It has new NGK spark plugs and i put new wiring in it and it runs great just not at full throttle. Any suggestions would be very helpful.

[James R]

So many things to address. The carbs need to be real clean and the floats set correctly. The ignition timing needs to be correct and finally the syncronization needs to be correct. Of course all of this is to no avail if the compressions are no good. Need to test that before anything else.