1985 75hp 4cyl 2 stroke low rpm in water

[Saleen27]

Hey everyone, new to the forum and first post. I recently bought a 1976 enterprise E17 front runner with an 1985 75hp on it. The engine started right up, idled great and rev’d up in neutral great. Took it to the water and after about 1/4 throttle it falls on its face, can’t move any quicker than maybe 7mph. Wether at 1/4 throttle or full throttle. At full throttle the engine sounds like it wants to pick up but doesn’t and as I de throttle to about half I feel a slight jump of power for a split second then back to 7mph. Rpms won’t go over 2200 or so. I’ve tested compression and am around 92 on all cylinders. Haven’t done a decant yet but will soon. Getting spark on all cylinders. Squeezing prime ball while at full or partial throttle doesn’t help the issue. Anyone have any ideas on what could be going on?

 

[racerone]

Clean carburetors first.

 

[fastjeff]

Try opening the idle mixture screws 1/4 to 1/2 turns OUT.

Jeff