posted 09-23-2004 09:08 PM ET (US)        

I generally run her around 3200 - 4200 rpm max. I have at times bumped her up to around 4500 (35 MPH-ish), which I might call 85-90% WOT.

I have no need to run WOT, but because of the age of my engine, should I keep the RPMs around where I do now, and never run WOT, or is it OK to run WOT on occasion?

There is no "redline" on my tach and I don't know if outboards even have a redline.

posted 09-24-2004 02:53 PM ET (US)            

If you choose to not run it through its entire working range, then I would suggest a high end synthetic oil and regular plug changes..

posted 09-24-2004 03:45 PM ET (US)            

When I bought the boat, she started before the key was even completely turned. Fired up nicely.

Now granted, I use the boat only on weekends, so when Saturday comes, I plug in the fuel line (I keep it unplugged from the motor), pump the ball and crank her. I choke her till she pops then crank from there. Sometimes she takes 3 or 4 attempts to get her going. Once she's warm, she starts very easily every time. So, I think this is just a case of getting the fuel into the system after sitting.

As for oil, I use the Evinrude brand and also Quicksilver. I read Evinrude uses something that does something with newer motors (forgot what I read), and since my motor was older I didn't think it would apply -- so I alternate.

Haven't looked at the plugs and need to inspect the lower unit oil.

posted 09-24-2004 05:27 PM ET (US)            

Get some of the de-carb spray, use it, then add some of the additaves to keep the carbon from building up.

posted 09-27-2004 05:59 PM ET (US)            

I guess I am trying to compare to a car, where you throw a rod, crack a head, burn a head gasket.

Just trying to imagine what would go first.

Thanks.

posted 09-27-2004 08:29 PM ET (US)            

Thanks all!

posted 09-27-2004 08:47 PM ET (US)            

The more critical one is mixture and/or timing. Take a 5 min full blast run, then bring it down to idle and shut it off (don't putt for a while). Check the plugs, if they are tan to dark, things are good. If they turned white on the tips, then either the carbs are leaning out or the timing is advanced (assuming correct plugs). Either condition can cause a melted piston at full.

Flip side is, excessive carbon build up from constant trolling and slow running will jam the rings, this in turn causes excessive wear and scratching on the cylinders. I think as many or more engines are damage by fishermen trolling all the time then by hot dogs running them hard...

posted 09-27-2004 09:21 PM ET (US)            

AYYYYY--- I SAID, AYYYYYYY, CAN I GET AN AMEN!

posted 10-01-2004 05:19 PM ET (US)            

Good thing I have a 2hp kicker. Bad thing is I usually leave it at home.

Prop I think is original.

posted 10-02-2004 08:36 PM ET (US)            

GREAT afternoon run today. I hauled the Katama out to Lake Pontchartrain and launched around 5pm. Lake was near glass, with a light breeze from the North.

I keep the fuel line unplugged from the motor, so I launch, plug it in, pump the ball once or twice until it's firm and turn the key unchoked. She doesn't fire, so I choke and try again, doesn't fire. I fast idle her, no choke, turn the key, she fires but doesn't start. I start as normal, bump the choke she fires and is running. So, about 4 attempts and she starts easily.

I don't think I have any problems so far, I just think I need to get fuel into the system.

So I head out into the Lake, Northbound in beautiful conditions. I run at about 3800 RPMs and about 32MPH for about 5 minutes, then I opened her up, WOT.

WOT per the gauges was 5200 RPM and 43MPH. I am in my 16' 7" 1971 Katama with a 1976 Evinrude 85HP 4 cylinder. I was running solo with 12 gals of gas and no cargo.

Now, I do know that I need to replace my throttle cables because reverse only goes up to 1500 RPM and the cable casing is cracked open at the engine. I have noticed no problems with forward. My only curiousity at this point is that the engine does not sound like she is whining like I am used to hearing a WOT engine do.

Instead, she sounds to be at what I would call about 90%, maybe 95%. Maybe the V 4 engine just doesn't do that.

Anyway, I ran WOT at 5000 - 5200 RPM and 40 - 43MPH for about 30 minutes. Every 5 or 10 minutes I would come down to 40 MPH or about 4800 - 5000 RPM. She showed no signs of problems.

I stopped because I wanted to adjust the pin that controls the fixed motor trim position (I have no power trim, only tilt) It is in the 2nd hole from the top. So I move the pin to the #1 top position to see what happens.

I barely touch the key and the motor fires effortlessly.
She cavitates when I engage forward, so I ease her up to speed and find she porpoises and hits high RPMS at lower speeds.

I kill the engine, move the pin down to #3 hole, bump the key, fires right up. Engage forward, bows riding lower, max speed is 40MPH at 5000 RPM. So, I kill the engine, put the pin where it originally was, #2 hole from the top. I bump the key, she fires right up. This position keeps the boat on a good plane, with no plow.

Engine runs perfectly and I think the WOT really cleaned her out.

Headed in before sunset as I watched mullet feeding topside and numerous fins break the surface. Wonderful afternoon ride in the Whaler.

Got to the launch, stepped onto the wharf and I hear at the next pier over, "Good old Boston Whaler!"

That made a perfect end to the day.

posted 10-02-2004 10:41 PM ET (US)            

It was short, it was different, but it was really great!

I want to see Ship Island. We picked up a brochure at a rest stop one day, I hope to make that run in the near future.

Better luck next time!

posted 10-03-2004 04:00 PM ET (US)            

All engines have a "red line", Most domestic engines fall (2 stroke) in the 5000-6000 RPM range. Engine speed isn't a factor with a 2 stroke OB. It is designed to run at full throttle without harm. That is why they are needle and roller bearing crank and rods! The highest wear is on cyl bores as the cyl blocks are aluminum, and relatively soft. By the way you can't run an engine rich as all domestic OB engines have had fixed jet carbs since the early 60,s. Actually if you don't run an OB hard you might dammage it. This is based on the experience of 356 Porsche "carria" engines of the late 50's & 60's who had engine failures due to flatting of the crank and rod jornals (roller & needle) due to lack of engine speed! Great high performance engins, just didn't like city driving!

Run it you won't hurt it! Meatalurgy doesn't change with time!

Best

posted 10-04-2004 09:23 PM ET (US)            

When I am running WOT, and I say it doesn't sound 100%, here is what I mean. My only comparison might not be an accurate comparison but it is all I have to go by. My dad runs a 50HP Mariner on the back of a 16' aluminum Duracraft (I think it's 16 feet, not sure) Everything 1989.

I have run that boat since 1989 and know how to trim her just right, I know the sound of that engine like my heartbeat. When I run with a load and the wind changes or the waves, I constantly trim and tweak the motor to get the maximum speed from the lowest RPM. Always trying to keep as much boat out of the water as I can just before she porpoises.

Anyway, with his engine, she maxes out WOT I think at about 5500 RPMs. When I hit about 4900 - 5200 rpms, she maxes out on speed. If I WOT her, the RPMs go up but no speed is gained. Also, when she is WOT, this 50 HP 3 cylinder Mariner is whining and you hear the difference between 5200 and 5500 RPMS. It almost sounds like if you add another 500 rpms the motor would explode. You can tell she's maxed out.

Ever hear a motocross dirt bike max out in a low gear, you know you've reached the limit and you better shift because the engines screaming? That's what I mean.

Now, with the Evinrude, I don't get that maxed out WOT, engine screaming sound. It's more like a car, you punch the gas to the floor, the engine revs as high as she will, but that's all it will rev and it doesn't sound like she'll blow.

So, I suppose my bottom line is that WOT I don't feel as if the engine is whining or screaming or being over revved. I can tell she is nearly maxed out on speed at 5000 RPM and I may barely gain anything at 5200. I thought maybe if I had bad throttle cables, she was not actually WOT, and being "governed" accidently.

Hope that helped.

posted 10-05-2004 11:15 AM ET (US)            

When I first rebuilt the motor, I ran it a bit rich, but only because it hadn't been run in 20 some odd years. I've started running closer to 50:1 as the year has advanced, since I've noticed carbon building up. So far this year, I think I've put more hours on her than she's had in 35 years. Pappaw would be proud.

posted 10-05-2004 11:29 AM ET (US)            

Your observations are valid. Based on old "marine archtetecture" base line. Once the hull design speed is reached, speed goes up with the cube (#3) of the Hp applied. That is why a hull will start to "porpose", it wants to fly but falls back into the water. This is different from "chine" walk which is side for side. Both are typical of hulls over their speed limit.

As for running rich. I was under the impression it was fuel, in the question. Rich oil will just get you carbon on the ports and ring lands. That is why they went to 50:1 back in the '60's. With synthetic, (somithing on the line of Amsoil) you could probibly pre mix and go even leaner!

Would I run a large block OB at WOT all day, no I would most likely use the aircraft rule of about 75% power for max all day running. It keeps the stress's low. The difference in sound you describe is most likely due to the reed valves in the induction system (behind the carbs). They "humm" at various levels based on engine speed they would have a "harmonic" sound level a some speed depending on the length of the reed valve and how far it is allowed to flex (depending on the retainer plate).

Later

posted 10-05-2004 04:13 PM ET (US)            

As I was sitting at the dock idling the other day, some guy came by with a 40 Merc, I guess 4 stroke. As he approached I could see him talking to his old lady in a normal tone of voice, but when he pulled along side and commented on my boat, he had to yell at me. I felt like some kind of endangered Spotted Owl murderer.

Ryan