Why won,t my 1988 200 hp ob motor rev above 2100 rpms under load?

New or rebuilt Alt.? If rebuilt I think you got a bad one.

have you changed the prop recently? Could be wrong size and pitch

Sounds like fuel supply problem, check the hose for kinks end the breather on your tank may even be the fuel filter inside the tank if older tank., if you sure that the carb and pump ok. If not sure, check the pump. Have fun

Check the spark at low RPMs. You may have a bad Powerpack.

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Sounds like the high speed jets need to be cleaned out.

when the engine has more strain add to its work load it will automatically adjust and bring the revs up to meet the new demand on the engine , hence the drop and then rise in revs

hi this may help,it sounds to me like the carb is running way to lean,this may cause the bike to miss at high rpm,also check that the spark plug cap is in good condition as it may be breaking down under high load conditions...cheers

Reving in neutral does not mean the same thing as under load. If you need to pull 4500rpm under load and for an instant the load was gone, you would probably overrev to 6500. With the cover off and motor not running move the throttle to full forward. Look at your carbs and see if the throttle plates are wide open. If they are not all wide open take it back to the dealer. The throttle adjustment is off. You need the full range of travel from idle to topend.

Have your fuel pump pressure checked....It sounds like it overheats and needs to be tested.....Fuel filted may also be clogging.