Force 70hp running issues

[Ron1234]

Hi i have a 70hp force that is running rough. It seems to have a intermittent miss and at around 3000rpm has a knocking noise coming from the reed valve area. I have replaced all plugs and leads and all cylinders have 120 psi compression. It vibrates heavily when on the water and struggles to make it max rpm. Help

 

[jerryjerry05]

Always include the year? serial# ?

Can of starting fluid.
Start motor and spray the SF around the intake side.
Base of the carb and around the fuel pump base etc.
If that makes a difference? smooths out, misses more, stalls.
Then it's sucking air someplace.

Check the fuel for water?

All plugs burning right?

 

[VivaLaMigra]

Ugh! Noise from "reed valve area" never a good thing; suspiciously close to the bottom end if you ask me. Hope I'm wrong for your sake.