1993 Yamaha 40HP 2 stroke

by Dale
(Mountain Home Ar. )

Help with my puzzle. Its a 1993 Yamaha 40HP 2 Stroke, jet drive. I can only get 4600RPM out of it, should be 5500. New fuel pump, plugs, coils, carbs have been cleaned and checked, even tried a different set of carbs, everything omed out within spects, shaft bearing checked and good, impeller is not touching, timing is dead on perfect. For the life of me I cannot figure out why I cannot get 5500rpms. Flat bottom river boat, so very little drag on boat.

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