I have a 1990 Yamaha 225 and I can only get 4200 rpm's. I did a comp. ck. and got 105 all around, replaced 2 suspected coils, 1 fuel pump, the plugs and used sea-foam in the carbs. my prop is 17 in Stainless steel with a slight cup. The engine is on a 234 Chaparral that sat for a long time but I...