[Tinkerer]

This is a thirsty beast.Assuming I want to go anywhere reasonably fast, I figure the best compromise on speed and fuel consumption is to get it up on the plane and keep just enough throttle on to keep it on the plane.I guess that the nearer I get to WOT the less efficient it gets and more fuel it consumes for less result.Anyone know?

[Laddies]

Tinkerer, I hate to tell you but, that would be THIRSTY---Bob :o

[rodbolt]

having water skied with one of them beasts I think the average was 6 gallons an hour at idle and carry 3 tanks at all times man what a fuel hungry beast.

[WillyBWright]

Give it full throttle until you're out of the hole, then back-off to about 7/8 throttle. You'll hear the motor get quieter, and you'll lose about 3mph over top speed. But that's about where they run their most efficient. Below 3/4 throttle they lose efficiency. The more solidly the boat is on plane, the less the motor has to work. Look at your wake. Big waves mean a lot of wasted energy. 6 gal/hr is about what I got. That's 10 min/gal.

[Tinkerer]

Thanks all.6 gal an hour is about right. Of course, only about half that is actually combusted.

[tabbott]

Where does the other half go?

[Tinkerer]

Originally posted by tabbott: Where does the other half go?

Straight out the exhaust. I was joking about the quantity, but these ain't the most efficient internal combustion machine ever made.

[marinemech]

tinkerer is correct up to 1/2 fuel goes out of exhaustif you want to play with high speed jets you can lean out motor. i did this to a 1965 75 h.p. it worked' fuel mileage went way upfind out what jets are in carbs then reduce size by .010 try motor and increase size until you get a reasonable running motor.note:you may have to use choke to get boat on plane.you also run the risk of burning a piston.its up to you

[Tinkerer]

marinemechYou're tempting me.Given the amount of wasted fuel I think there's a bit of leeway before I'd burn a piston. Or maybe they need to be swimming in fuel to avoid holing one.If I had the knowledge I suspect that the trick might be to work out how to change the petrol / oil ratio as the jets change to keep it on the right side of lean. I'm thinking that a fluid of a given viscosity will reach a point where it goes through a smaller hole slower than a bigger one, so when that point is reached the viscosity has to be adjusted to allow the right flow rate. So maybe a 50:1 goes to a 60:1 to allow enough fuel to pass. If it's left at 50:1 less fuel will go through and the leaning effect of the smaller jet will be greater than just the effect of the smaller jet.I'm not explaining this well because I don't know enough to be clear, but maybe you can get my drift.