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Harry Krause August 3rd 04 08:51 PM

4-stroke Yamaha engine problems (major)
 
Lloyd Sumpter wrote:
On Sun, 01 Aug 2004 16:44:41 -0400, mijoy wrote:

If you are insinuating that 900 hours is a lot, you must be one of those 50
hours a year people.


I was thinking that. If 900hrs is a lot for an outboard, I'm glad I have
a (diesel) inboard! The last one had 4000hrs on it, and was still pretty
good (I replaced it mainly because it was underpowered). I was told gas
inboards should last 2500hrs or so between overhauls. 900hrs? Barely
broken in!

Lloyd Sumpter
"Far Cove" Catalina 36


I don't want to overgeneralize, but most pleasureboat outboards are
operated a bit differently than most pleasureboat diesels. Further,
Lloyd, your former sailboat diesel probably had less stress on it in use
than my little diesel lawn tractor engine. And less horsepower, possibly.


--
"There's an old saying in Tennessee - I know it's in Texas, probably in
Tennessee - that says, fool me once, shame on - shame on you. Fool me -
you can't get fooled again." -George W. Bush, Nashville, Tenn., Sept.
17, 2002

Lloyd Sumpter August 4th 04 03:15 PM

4-stroke Yamaha engine problems (major)
 
On Tue, 03 Aug 2004 15:51:42 -0400, Harry Krause wrote:

Lloyd Sumpter wrote:
On Sun, 01 Aug 2004 16:44:41 -0400, mijoy wrote:

If you are insinuating that 900 hours is a lot, you must be one of those 50
hours a year people.


I was thinking that. If 900hrs is a lot for an outboard, I'm glad I have
a (diesel) inboard! The last one had 4000hrs on it, and was still pretty
good (I replaced it mainly because it was underpowered). I was told gas
inboards should last 2500hrs or so between overhauls. 900hrs? Barely
broken in!

Lloyd Sumpter
"Far Cove" Catalina 36


I don't want to overgeneralize, but most pleasureboat outboards are
operated a bit differently than most pleasureboat diesels.


True, but opposite to the way you're suggesting.

Further,
Lloyd, your former sailboat diesel probably had less stress on it in use
than my little diesel lawn tractor engine. And less horsepower, possibly.


I won't argue the horsepower, but that's exactly the point. My "little
diesel" was run 90-100% throttle for most of it's life. Whereas an
overpowered outboard is often run at idle (trolling), very low rpm
(no-wake zones) or maybe 70% for cruising.

And since a planing outboard boat goes so much faster (and less
comfortable!), it rarely runs at that for more than a few hours. OTOH, my
little diesel often ran 90% for 8-10 hrs, chugging along at 5 knots.

Then again, since diesels are BUILT for full-power use, maybe you're right
about the stress...

All I'm hearing from this is that outboards aren't built for constant
high-power use. Is that what you're trying to say, Harry? ;)

Lloyd Sumpter
"Far Cove" Catalina 36


Greg August 4th 04 04:33 PM

4-stroke Yamaha engine problems (major)
 
I believe 2 strokes are built for WOT or close to it but 4 strokes will last a
lot longer if you keep them under 4000 RPM most of the time. It is simply the
number of reciprocating parts. Most of my hours are put on under 3500 RPM ...
but I want it to last 2000 hours. So does Mercury, because it will be under
warranty for about that long at my current usage.

mijoy August 5th 04 12:52 AM

4-stroke Yamaha engine problems (major)
 

"Greg" wrote in message
...
I believe 2 strokes are built for WOT or close to it but 4 strokes will

last a
lot longer if you keep them under 4000 RPM most of the time. It is simply

the
number of reciprocating parts. Most of my hours are put on under 3500 RPM

....
but I want it to last 2000 hours. So does Mercury, because it will be

under
warranty for about that long at my current usage.


I try to keep mine at 3800-4200 while cruising. I'm hoping the same thing,
that the slightly reduced rpm will yield better longevity.
It's also significantly better fuel economy then runnning at 4500-4800




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