Yamaha P250 O/B

[robp]

Someone I know has just bought a day boat with a Yamaha P-250 outboard. The boat is only 12'6", so it should plane easy. However it sounds as though the engine has seen better days and doesn't have enough torque. It will rev OK in neutral but can't get the boat up in gear. Anyone know this motor? and is there anything simple he can do as a stop-gap on a low budget? Rings, even pistons - or is it the inevitable expensive job?

Thanks for any info

 

[markc]

Hi, I don't know the engine, but the first thing I would check is the prop size, providing the engine isn't showing signs of big engine trouble. If the prop is too big, or is too corse then it will hold the engine back.

Mark

 

[robp]

Yes, thanks Mark. I had assumed when he told me about the problem that it would be an original prop. Maybe even an original engine/boat combination and that the engine is just tired. We'll check that though.

BR
Rob

 

[Guest]

I'm not sure of the designation of Yamaha engines. Is 250 the size or power? I'd think a 25hp engine could be a bit marginal. If the engine runs smoothly enough in idle then it's unlikely to be anything mechanical. If it pops and bangs under load then it's fuel or electrics. If it is just struggling to get onto the plane ir could be the prop.You could try getting someone as far forward as possible. Helps get you over the hump.

Doug

 

[robp]

Thanks yr reply Doug. Yes it's 25 HP, which apparently should get this boat on the plane easy. I don't think he's getting enough power to think about putting someone up front or "jumping" foward to flip the stern up. It seems to be a question of whether the motor still has enough "grunt". He's checking throttle cable travel now.

Thanks again.

Rob

 

[Guest]

You know we do sometime miss the obvious like are we getting full throttle movement. A few months ago I was complaining about how my car was really down on power. Few days later I was hoovering the carpet and moved it back to it's proper place. Next time I drove it I got full throttle again and nearly drove into the bushes!

Doug

 

[Guest]

Re: choke?

Hi, no don't know the engine. But if it starts but just can't get whoofing along, mebbe check choke is fully closed.

If ok, then praps either stick it on another smaller boat for a blast. We have 15hp on pump-up 3m inflatable, only planes with one or two small people though, weight a big issue. Can't believe that mucking about with prop would make the huge difference you need plane v not planing, provded prop clean and filed off kinks.

If your are solenty, Ron Hale in Portsmouth is a proper o/b shop, nice chap. Round the back he has big tanks to run up the engines in, worth a trip, spare everything and trade-ins.

 

[robp]

Re: choke?

Matts, thanks yr reply. Seems that when out of gear it revs fast and freely. Points to torque. What did he say to me the other day? "It's technically described as the anacronym for Combined Rotational Anti Planing". I think that means it might be worn out! He is in Pompey so he's off to Ron Hale on weekend.

Thanks again.
Rob

 

[Guest]

Re: why Pompey?

I never understood the nickname of portsmouth. Praps, cos it's covered in crud, like Pompeii?

 

[robp]

Re: why Pompey?

Hmm. Not been able to find out. Just an endearment? I'll keep trying now! nm

 

[duncan]

12'6 isn't the vital fator - it's weight.
rough calc basis is normally accepted to be 16 : 1 KGS to HP for an outboard boat to plane - gives you 400 kg all up to play with.
2 guys / small boat / bit of fuel - no lunch - should be OK with right prop / engine trim set right.

People have been known to stick nice 2nd hand props on engines without regard for pitch.........

 

[awesomo84]

Thanks yr reply Doug. Yes it's 25 HP,
Rob

p250 is a 15pk outboard motor.

greets