Idling a bigger 2 Stroke...good or bad?

[Bigprairie1]

Anyone have an opinion on whether or not you should idle a bigger (90hp) 2 stroke for extended periods? Is this harmful to the motor or just cause tuning problems or? Maybe mix it up with the odd higher speed/rpm run? which is what I currently try to do.
Often we will idle around the lake at slow speeds just to tour, visit, etc and I have wondered if this was good for the motor or not. My wife is a little more partial to these touring speeds rather than my preferred higher speeds...which is why I sometimes head out without anyone else on board.
Anyhow, I guess alternately I would look into getting a smaller 'kicker' motor or God forbid a slower boat.....naaah, best to get some info on this first.
I have heard about it being more acceptable on 4 strokes but...?
Any opinions on this guys? good or bad?
Thanks
BP

 

[thenotsofreeboat]

Re: Idling a bigger 2 Stroke...good or bad?

I once read something on here that talked about that and called it trolling. I think the agreement was it is just causing more carbon build up but running it at a higher speed after that would help keep it from forming anything harmful. Tell the wife you "have to" and give the boat a good run. In any case just run some sea foam in it and call it good.

 

[jtexas]

Re: Idling a bigger 2 Stroke...good or bad?

Because there is oil in the gas, and because the oil is generally mixed in a proportion to adequately lube the motor at high speeds, there's generally excess oil at low speeds, when the combustion temps aren't high enough to burn it all off. In an old-school motor especially carbed, that's compounded by the fact that you don't have a computer adjusting the mixture in response to feedback from o2 sensors and such. Outboard carbs have only 2 or 3 circuits to meter air & fuel across the whole throttle range. And, outboards need to be tuned for optimum performance at the upper end of the RPM range. All of which leads to carbon build-up at idle and trolling speeds.

If you idle a lot, put seafoam in your fuel, widen your spark plug gap by .005 to .01, and give her some good quality WOT time to make up for it.

 

[Bigprairie1]

Re: Idling a bigger 2 Stroke...good or bad?

Because there is oil in the gas, and because the oil is generally mixed in a proportion to adequately lube the motor at high speeds, there's generally excess oil at low speeds, when the combustion temps aren't high enough to burn it all off. In an old-school motor especially carbed, that's compounded by the fact that you don't have a computer adjusting the mixture in response to feedback from o2 sensors and such. Outboard carbs have only 2 or 3 circuits to meter air & fuel across the whole throttle range. And, outboards need to be tuned for optimum performance at the upper end of the RPM range. All of which leads to carbon build-up at idle and trolling speeds.

If you idle a lot, put seafoam in your fuel, widen your spark plug gap by .005 to .01, and give her some good quality WOT time to make up for it.

The low tech fuel system on this motor definitely jives with what your saying Jtexas. There is definitely no advanced technology at work on this particular motor and although it runs very well all in all but it does seem to load up after say 1/2hr-1 hr or so at which time I like to open it up.....mind you I like to open it up anyway.
I've never tried the seafoam stuff although I've heard a lot about it within the forum. Can it be straight run through the gas tank? I thought it was a fairly protracted process to do a seafoam purging? Who makes it?
Thanks
BP

 

[dingbat]

Re: Idling a bigger 2 Stroke...good or bad?

I troll a carbed 200 HP Evinrude at 1000-1300 rpm for hours on end at a time and have never had a problem with loading or carbon build-up.

The trick is to use fresh fuel and a good quality synthetic or semi synthetic oil. The cheap stuff will not cut it in this application.

To give you an idea of how much I trolling I do we put over 70 hours on the motor since the first of April with an average speed of 4.1 kts. The average speed would have been lower had it not been for the 8-10 mile run to anf from the fishing grounds at 26-27 kts each day.

 

[jtexas]

Re: Idling a bigger 2 Stroke...good or bad?

good advice about the synth.

You can clean out your motor with an intense seafoam treatment, but if you'll add an ounce or so per gallon of gas it'll discourage the buildup.

 

[tashasdaddy]

Re: Idling a bigger 2 Stroke...good or bad?

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

in the old days we use to open our spark plug gap and additional .005-.010 this would cut down of the loading up of the motor. still works today.