posted 04-22-2003 05:45 PM ET (US)
Hi, Blueboat,Your boat should run in the mid 30s at 5500-6000rpm with that engine, in good tune and properly rigged and propped. My guess would be that a 17" prop is correct.
You have an engine problem. Could be running on 2 cylinders with only 3500 @ WOT (33,500rpm!!??). That engine will pretend to be running great on 2 unless you put a load on it.
Some troubleshooting is in order.
Check each plug wire at idle for a hot, blue spark to the block and note engine speed while doing so.
A cylinder that has spark but doesn't cause rpm to drop when the lead is off is a dead cylinder. See what happens if you squirt a bit of fuel mix into its carb. If that picks it up overhaul that carb.
Next, see what happens if you pump your primer bulb when under power. Picks up? Fuel pump or filter.
Let us know what you find.
Red sky at night.. .
JB