pstephens46; propeller and motor rotation

[rodbolt17]

most aircraft gearboxs do not use a back draft cut dog clutch with a mechanical slam shift.
most aircraft engines do not stick the ex tube 3ft deep in the water.
I have seen water injestion due to backing down hard on just one engine with the injested one idling.
I have seen it due to running aground at high speed.
I have seen it due to a rapid throttle down due to a *****ing motor that was not locked down.
I have even seen one idiot do it because he wanted to inspect the spark plugs.
you simply cannot take a pair of F250 motors at 5800 RPM and pull the stop lanyard and expect nothing to happen when you buried the motors.
but your simply not going to ever see it cause the propshaft turned the driveshaft backwards.

[pstephens46]

most aircraft gearboxs do not use a back draft cut dog clutch with a mechanical slam shift.
most aircraft engines do not stick the ex tube 3ft deep in the water.
I have seen water injestion due to backing down hard on just one engine with the injested one idling.
I have seen it due to running aground at high speed.
I have seen it due to a rapid throttle down due to a *****ing motor that was not locked down.
I have even seen one idiot do it because he wanted to inspect the spark plugs.
you simply cannot take a pair of F250 motors at 5800 RPM and pull the stop lanyard and expect nothing to happen when you buried the motors.
but your simply not going to ever see it cause the propshaft turned the driveshaft backwards.

There has to be some detail here. Please elaborate. Need a good laugh this am.

[99yam40]

I am sure the next lines in his post tell the rest of the story

[pstephens46]

I am sure the next lines in his post tell the rest of the story

Maybe. I have never had the urge when running at 5800 or above to suddenly kill power and inspect the plugs. I am usually trying to hang on and avoid any large bumps coming my way. "Damn, I need to check the plugs!" I expect he may have found a little water when he checked a couple of them.

Maybe he thought a quick soak of Draino was needed.

[zenoahphobic]

Maybe. I have never had the urge when running at 5800 or above to suddenly kill power and inspect the plugs. I am usually trying to hang on and avoid any large bumps coming my way. "Damn, I need to check the plugs!" I expect he may have found a little water when he checked a couple of them.

Maybe he thought a quick soak of Draino was needed.

Quite common in the racing/performance world.

You need to run engine at high load and speed and then stop to inspect plugs for colour indicating lean or too rich a fuel mixture.

The "idiot" referred to probably had no other way to do this.

[TownsendsFJR1300]

Quite common in the racing/performance world.

You need to run engine at high load and speed and then stop to inspect plugs for colour indicating lean or too rich a fuel mixture.

The "idiot" referred to probably had no other way to do this.

+1 ^^^^

That's exactly what they did BEFORE computers monitored everything.

Carburetors to be dialed in on a new engine with different cam's exhaust, etc..

[zenoahphobic]

And with all that and fuel injection, some people still like to fine tune (heat range) their plugs to suit their type of riding/driving.

[pstephens46]

+1 ^^^^

That's exactly what they did BEFORE computers monitored everything.

Carburetors to be dialed in on a new engine with different cam's exhaust, etc..

How are you going to fine tune an F250? I intended to quote zeno's post...

Or maybe the question is why would you attempt to fine tune an F250? Not to mention 2 of them. It's one of the best Yam motors made. Next to an F150 of course

[zenoahphobic]

How are you going to fine tune an F250? I intended to quote zeno's post...

Or maybe the question is why would you attempt to fine tune an F250? Not to mention 2 of them. It's one of the best Yam motors made. Next to an F150 of course

You probably would not fine tune an F250. But it simply being an engine like any other, it is open to modify. But I would expect space around them and cost would deter most. I guess you might be implying that it runs and performs fine as it is.

There are enormous amounts of stuff out there that satisfies those that want to make things better particularly for cars, not so for outboards.

With ECUs connected to sensors there is less and less for those that have an urge to "tune" with, except for the humble spark plug.

[pstephens46]

I could see fooling with bass boat motors and other fresh water junk. If they blow, maybe you are a couple hundred yards from shore. Salt water, hmmm. Not so much. I would like to see one of those TX flats boats with a 300HPDI strapped to the back. Fashion a seat belt with a crash helmet and you are off. On a lake of course.

Forgot, you would need a pair of those Gomer goggles too. Vietnam vintage.

[dray0151]

I could see fooling with bass boat motors and

other fresh water junk

. If they blow, maybe you are a couple hundred yards from shore. Salt water, hmmm. Not so much. I would like to see one of those TX flats boats with a 300HPDI strapped to the back. Fashion a seat belt with a crash helmet and you are off. On a lake of course.

Forgot, you would need a pair of those Gomer goggles too. Vietnam vintage.

Now lets be nice, I like my fresh water fishing.

[pstephens46]

Just playing...

[99yam40]

I have read about some of those flats boats grabbing air and flipping when running at speed and chop with wind.

I prefer not to run fast enough to cause something like that.

[TownsendsFJR1300]

How are you going to fine tune an F250? I intended to quote zeno's post...

Or maybe the question is why would you attempt to fine tune an F250? Not to mention 2 of them. It's one of the best Yam motors made. Next to an F150 of course

As I and Zeno posted, that "procedure" was for much older CARBED machines, when there were NO computers.

There is really NO reason to do that "procedure" on a FI'ed F250, / 150, ANY FI'ed engine.

Now, high end say race car engines (computerized), they can fine tune(via computers/laptap) timing, fueling, etc and with a sniffer, monitor if too rich, too lean, etc.


The dumb ass with an F250, doing a "turn off" at high speed (on purpose), there is no reason to. And then as RB stated, rushing water pushes up thru the exhaust and causes major issues/damage.

Now if he fell off, had his lanyard attached, the engine will do the same, turn off as designed.

Re Jethro's pic's (Yamaha pic's), that's probably the reason about the reverse rotation sensor Yamaha is using..




.

[rodbolt17]

there is and never was a reason to suddenly chop the throttle at speed.
it is and was a myth.
at the end of the run you simply backed off the throttle,shifted to N and then cut the engine.
then inspect the plugs.
but to simply kill the engine at speed on a sterndrive or an outboard is simply stupid unless it is an actual emergency.
maybe I can post some pics of some rods I have hanging on my wall or a piston or two.