Is 100:1 ok?

SundayMoney

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Nov 22, 2008
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I have an '89 Evinrude 8hp. The manual says to run 50:1 when used under high speed operations or when used infrequently.

It also says I can run it at 100:1 when used at lower speed or when used frequently.

I have it on a 14' Lund, it won't get the boat on step, so the high speed operation is out. Its used as a trolling motor.

I'd like to cut some smoke and run it at 100:1. The only thing keeping me from doing the 100:1 is that apparently after a few years the 100:1 recommendation was dropped.

So,with strictly low speed operation,would you run it at 100:1?

If not 100:1,maybe something less than 50 but more than 100?
 

idrownworms

Petty Officer 1st Class
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Aug 7, 2008
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224
Re: Is 100:1 ok?

why take the chance. oil is cheap, pistons, rings, cylinders/blocks are expensive
 

Rick.

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Re: Is 100:1 ok?

How can you be assured the motor will only go at trolling speed. I'm always thinking the fishing will get better if I move to the other side of the lake. But I'm often wrong. I would not do it but there is an article where a guy carries two tanks, one 100:1 and the other 50:1 and uses the one for trolling only and the other for to and fro. They say synthetic oil produces less smoke so that is the direction I would go rather than less oil. Best of luck. Rick.
 

samo_ott

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Jun 18, 2006
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Re: Is 100:1 ok?

OMC revamped all the 100:1's to 50:1 in the 90's I believe. It's up to you. I'd use synthetic oil. I do in all my engines.
 

emdsapmgr

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Dec 9, 2005
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11,551
Re: Is 100:1 ok?

OMC made some of these engines for a few years. They came with special tanks that had an internal section for oil, and the tank would mix it before it got to the engine. After a few years, OMC issued a service bulletin indicating that these tanks should not be used as designed and the fuel in them should be premixed at 50 to 1. The tanks were discontinued from sale immediately. Your engine should use 50 to 1 fuel to oil. The 100 to 1 ratio worked fine and was not the real problem. OMC found that the oil film strength was so thin, that when an engine was stored for a long period of time-the interals of the engine could rust badly, causing powerhead failures. The rust problem was usually as a result of storing over the winter without proper winterization.
 

steelespike

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Apr 26, 2002
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19,069
Re: Is 100:1 ok?

I would stick with 50:1 100:1 leaves no margin for error,mixing or in the event of an over heat.
Unless that boat or you are a real load that motor should plane.It would require careful weight placement and motor trim.You might try a tiller extension so you can get farther forward.We had a little 5hp on a 12ft steel boat it would pop on plane with a 180 pounder and the extension handle.
 

SundayMoney

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Nov 22, 2008
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Re: Is 100:1 ok?

Unless that boat or you are a real load that motor should plane.It would require careful weight placement and motor trim.You might try a tiller extension so you can get farther forward.We had a little 5hp on a 12ft steel boat it would pop on plane with a 180 pounder and the extension handle.


The boat dry is 270,the engine is about 55. My son and I are close to 300 together. Tackle box,couple rods,anchor,and she doesn't get on plane.

I've considered a hydro foil or whatever they're called. Don't know if that would be enough to put us over the edge though.
 

OptsyEagle

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Sep 13, 2006
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1,359
Re: Is 100:1 ok?

You could probably survive on half the oxygen also if you didn't move around much and walked very slowing, but that wouldn't be very good for you either.

Use 50:1
 

Rick.

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3,740
Re: Is 100:1 ok?

I have also heard although I can't confirm it, that the synthetics are biodegradable(sp). Can anyone say if that is true of does it depend on the specific oil? I looked at the Amsol link and didn't see anything about it being biodegradeable. When I run my 9.5 in a barrel for any amount of time it produces a lot of exhaust muck. Muck that is normally going into the water body I'm fishing so I think I do understand your concern. I just don't think reducing the oil mix is the way to address it. Rick.
 

cbavier

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Apr 8, 2007
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1,363
Re: Is 100:1 ok?

I vote 50.1

If it's smoking it could be a several things .
1- Either running too rich and that could explain partially why it's smoking and you can't get up on plane (besides perhaps the weight inside) in the boat. I had a 14 ft and a 9.9 HP Johnson wouldn't plane mine so I went to a 15hp and that did the job and I and my Buddy weighed about 320 Lbs. Plus gear.

2- Burned or scored rings. Will also cause loss of power

3- Wrong or bad Spark Plug

But still the mix is now 50.1
 

CATransplant

Admiral
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Feb 26, 2005
Messages
6,319
Re: Is 100:1 ok?

Whenever someone proposes that I run an older motor on a higher ratio of fuel:eek:il than is recommended, I always want to ask them if they'll pay for repairs if that doesn't work out.

As someone else in this thread said, oil's cheap. Engine parts are not.

OMC changed their oil recommendation to 50:1 for all those engines that were marked 100:1. Why would anyone do anything different from what the manufacturer recommended?

Seems like foolishness to me.
 
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