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Default 5000 - 8000 RPM Surprise

On Mon, 15 Jun 2009 10:00:18 -0400, "Reginald P Smithers III, Esq."
wrote:

John H wrote:
On Mon, 15 Jun 2009 07:50:33 -0400, "Reginald P Smithers III, Esq."
wrote:

Mike Slater wrote:
"Eisboch" wrote in message
...
"Mike Slater" wrote in message
news:knfZl.742458$yE1.158636@attbi_s21...
I was cruising along in my 24ft pontoon boat when I got a real
surprise. Somebody please tell me how and why I could be running wide
open throttle at my normal 5500 rpm and then suddenly the boat took
off like a bat out of hell running at 8000 rpms and 25mph??? I never
touched the throttle. It has never run that fast ever. After about 2
minutes it went back down to 5500 and never did 8000 again. Its a
60hp mercury Bigfoot outboard. It has never done this before and I
don't even know how it could rev that high and go 25mph. Normal is
5500 and 17mph. What happened??

Mike

Is it a two stroke? I've often noticed on 2 stroke weed wackers or
chain saws that just as you are about to run out of fuel they speed
up. I think they start running lean due to air in the fuel line.
Is it possible you had a temporary air leak in a line and a similar
thing is happening?

Eisboch

Yep. Its a two-stroke. It really caught me by surprise. Next time I
will look at the clear inline gas filter down near the primer bulb to
see if its empty if and when it happens. It was only my second outing
this year so who knows what going on and was too shocked to think about
looking at the fuel situation. You know, it sounded great at 8000 revs.
Mike,
You may want to consider dropping back to a "cruising" rpm, instead of
running it WOT. Running the boat at WOT will shorten the life of the
engine considerably and use about 3 times the gas. For most boats, the
best gph or mpg is about 3400-3600 rpm. You shouldn't pick up much
incremental speed at WOT.


I ran mine at WOT yesterday, for the first time. Only did it for about
15 seconds. Man, that little boat is fast!
--
John H

"The democracy will cease to exist when you take away from those
who are willing to work and give to those who would not."
Thomas Jefferson


That sound of the wind whistling in your ears, was really the sound of
the engine sucking down the gas.


That's another reason I usually hold it to 3400. It seems to be happy
there.
--
John H

"The democracy will cease to exist when you take away from those
who are willing to work and give to those who would not."
Thomas Jefferson
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First recorded activity by BoatBanter: Jun 2009
Posts: 45
Default 5000 - 8000 RPM Surprise

John H wrote:
On Mon, 15 Jun 2009 10:00:18 -0400, "Reginald P Smithers III, Esq."
wrote:

John H wrote:
On Mon, 15 Jun 2009 07:50:33 -0400, "Reginald P Smithers III, Esq."
wrote:

Mike Slater wrote:
"Eisboch" wrote in message
...
"Mike Slater" wrote in message
news:knfZl.742458$yE1.158636@attbi_s21...
I was cruising along in my 24ft pontoon boat when I got a real
surprise. Somebody please tell me how and why I could be running wide
open throttle at my normal 5500 rpm and then suddenly the boat took
off like a bat out of hell running at 8000 rpms and 25mph??? I never
touched the throttle. It has never run that fast ever. After about 2
minutes it went back down to 5500 and never did 8000 again. Its a
60hp mercury Bigfoot outboard. It has never done this before and I
don't even know how it could rev that high and go 25mph. Normal is
5500 and 17mph. What happened??

Mike
Is it a two stroke? I've often noticed on 2 stroke weed wackers or
chain saws that just as you are about to run out of fuel they speed
up. I think they start running lean due to air in the fuel line.
Is it possible you had a temporary air leak in a line and a similar
thing is happening?

Eisboch

Yep. Its a two-stroke. It really caught me by surprise. Next time I
will look at the clear inline gas filter down near the primer bulb to
see if its empty if and when it happens. It was only my second outing
this year so who knows what going on and was too shocked to think about
looking at the fuel situation. You know, it sounded great at 8000 revs.
Mike,
You may want to consider dropping back to a "cruising" rpm, instead of
running it WOT. Running the boat at WOT will shorten the life of the
engine considerably and use about 3 times the gas. For most boats, the
best gph or mpg is about 3400-3600 rpm. You shouldn't pick up much
incremental speed at WOT.
I ran mine at WOT yesterday, for the first time. Only did it for about
15 seconds. Man, that little boat is fast!
--
John H

"The democracy will cease to exist when you take away from those
who are willing to work and give to those who would not."
Thomas Jefferson

That sound of the wind whistling in your ears, was really the sound of
the engine sucking down the gas.


That's another reason I usually hold it to 3400. It seems to be happy
there.
--
John H

"The democracy will cease to exist when you take away from those
who are willing to work and give to those who would not."
Thomas Jefferson


Trimmed up?
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First recorded activity by BoatBanter: Aug 2008
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Default 5000 - 8000 RPM Surprise

On Mon, 15 Jun 2009 20:08:41 -0400, D K
wrote:

John H wrote:
On Mon, 15 Jun 2009 10:00:18 -0400, "Reginald P Smithers III, Esq."
wrote:

John H wrote:
On Mon, 15 Jun 2009 07:50:33 -0400, "Reginald P Smithers III, Esq."
wrote:

Mike Slater wrote:
"Eisboch" wrote in message
...
"Mike Slater" wrote in message
news:knfZl.742458$yE1.158636@attbi_s21...
I was cruising along in my 24ft pontoon boat when I got a real
surprise. Somebody please tell me how and why I could be running wide
open throttle at my normal 5500 rpm and then suddenly the boat took
off like a bat out of hell running at 8000 rpms and 25mph??? I never
touched the throttle. It has never run that fast ever. After about 2
minutes it went back down to 5500 and never did 8000 again. Its a
60hp mercury Bigfoot outboard. It has never done this before and I
don't even know how it could rev that high and go 25mph. Normal is
5500 and 17mph. What happened??

Mike
Is it a two stroke? I've often noticed on 2 stroke weed wackers or
chain saws that just as you are about to run out of fuel they speed
up. I think they start running lean due to air in the fuel line.
Is it possible you had a temporary air leak in a line and a similar
thing is happening?

Eisboch

Yep. Its a two-stroke. It really caught me by surprise. Next time I
will look at the clear inline gas filter down near the primer bulb to
see if its empty if and when it happens. It was only my second outing
this year so who knows what going on and was too shocked to think about
looking at the fuel situation. You know, it sounded great at 8000 revs.
Mike,
You may want to consider dropping back to a "cruising" rpm, instead of
running it WOT. Running the boat at WOT will shorten the life of the
engine considerably and use about 3 times the gas. For most boats, the
best gph or mpg is about 3400-3600 rpm. You shouldn't pick up much
incremental speed at WOT.
I ran mine at WOT yesterday, for the first time. Only did it for about
15 seconds. Man, that little boat is fast!
--
John H

"The democracy will cease to exist when you take away from those
who are willing to work and give to those who would not."
Thomas Jefferson
That sound of the wind whistling in your ears, was really the sound of
the engine sucking down the gas.


That's another reason I usually hold it to 3400. It seems to be happy
there.
--
John H

"The democracy will cease to exist when you take away from those
who are willing to work and give to those who would not."
Thomas Jefferson


Trimmed up?


Nicely!


--
John H

"The democracy will cease to exist when you take away from those
who are willing to work and give to those who would not."
Thomas Jefferson
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