Years back, my OX66 wouldn't break 5000 rpm even in spring with a new bottom.
Talked with my Yamaha mechanic and he asked when I'd last replaced my low pressure fuel pumps... uh, never since I'd owned her.
3 new pumps later and she was singing along at 5300 rpm.
Don't know if the four strokes have a similar fuel system, but it might be worth asking.
Once I raised the motor, added the Merc 17p, and gave her a good tune-up with new fuel pumps, she would regularly see 34 knots @ 5200 to 5300 (5500 was max for this motor).
Talked with my Yamaha mechanic and he asked when I'd last replaced my low pressure fuel pumps... uh, never since I'd owned her.
3 new pumps later and she was singing along at 5300 rpm.
Don't know if the four strokes have a similar fuel system, but it might be worth asking.
Once I raised the motor, added the Merc 17p, and gave her a good tune-up with new fuel pumps, she would regularly see 34 knots @ 5200 to 5300 (5500 was max for this motor).
