What is the trick about starting a two cycle engine that sat for too long

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c5vettster

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  • / What is the trick about starting a two cycle engine that sat for too long
I hope my experience isn't unique and somebody has a straightforward solution. When faced with starting an 2-cycle equipment that sat for a long time I am always at a loss. One way or another I get it to start after which it usually starts on a single pull but I cannot put my finger on what actually makes it start. Here is an example. I am trying to start a modestly used Tanaka TBC-270PF trimmer. It was stored for about a year with gasoline drained and a bit of oil in the cylinder. The trimmer has excellent 155psi compression, spark you can light a cigarette with and it doesn't fire up even on the starting fluid. I checked the spark plug and it shows fuel. I have several of these and by fussing around them, they eventually start but it takes hours of pulling on it. Is there a trick to this?
 
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  • / What is the trick about starting a two cycle engine that sat for too long
We have a very poor way of measuring how much starting fluid the spark plug experiences when it is squirted into the carburetor opening, which usually is way too much fuel to air ratio. I suggest using it for a cleaning fluid or pitch it in a dumpster.

Suggestion for starting: remove spark plug and crank until all oil is pumped out that was used for storage. Install a new plug, remove the air filter and put about a half an eye dropper of gasoline in the carburetor throat so approximately the correct amount of gas can be inhaled into the cylinder on the intake stroke. That's worked for me for several decades on engines that's been on the shelf for a year.

I've retired from starting and overhauling these 2 cycles pictured and the above procedure would be worthless there.:laughing:
 

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RDA.Lawns

RDA.Lawns

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  • / What is the trick about starting a two cycle engine that sat for too long
That's a big motor there ...lol We had big engines in the oil fields used on drilling rigs and pumps/compressors but don't think we had any that big
 
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c5vettster

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  • / What is the trick about starting a two cycle engine that sat for too long
SeniorCitizen said:
We have a very poor way of measuring how much starting fluid the spark plug experiences when it is squirted into the carburetor opening, which usually is way too much fuel to air ratio. I suggest using it for a cleaning fluid or pitch it in a dumpster.

Suggestion for starting: remove spark plug and crank until all oil is pumped out that was used for storage. Install a new plug, remove the air filter and put about a half an eye dropper of gasoline in the carburetor throat so approximately the correct amount of gas can be inhaled into the cylinder on the intake stroke. That's worked for me for several decades on engines that's been on the shelf for a year.

I've retired from starting and overhauling these 2 cycles pictured and the above procedure would be worthless there.:laughing:
Click to expand...

Capital advice. I suppose the stoichiometrics of fuel/air/oil mixture is a lot more important in these tiny engines compared with larger 4-cycle engines.
One more question. Does a spark plug really make a difference? By that I mean, in a 4-cycle equipment I am yet to see a situation where a sparkplug that works in the air did not work in the combustion chamber. In other words should I make a trip to a walmart and get a new spark plug or the old one made do just as well?
 
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  • / What is the trick about starting a two cycle engine that sat for too long
What I know about spark plugs could be put in a thimble, but I have been acquainted with 2 cycle dirt bike guys that wouldn't leave home without a couple of new spark plugs in the bag of goodies. There just seems to be something about a 2 cycle that once a plug is fouled, at least replace it for now but it may run later in a hot engine.

Funny thing, even a few engines like that 2,000 HP 2 cycle pictured would pretty much keep Champion Plug Co. in business.

A/C made a plug tester years ago and with those the difference in firing at atmospheric pressure and under more pressure, the difference in firing ability could be seen.

Make a trip to buy a new plug? I wouldn't. Try the old plug first, then if that doesn't work try heating the plug either with a torch or even a gas range will do it. And if possible on that small equipment, during cold weather, bring it indoors to warm over night. Every little bit sometimes helps and can lead to a arm that's not so sore from pulling the rope.
 
primerbulb120

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  • / What is the trick about starting a two cycle engine that sat for too long
Bad plug has 3 symptoms on 2 stroke engines as far as I know:

1. Won't start at all
2. Starts but runs rough
3. Starts cold and runs just fine till you turn it off, but then it won't restart till it cools down again.

Old spark plugs that have sat for a while should be replaced. In my experience they typically work the first few times then quit unexpectedly while you're using the machine.
 
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c5vettster

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  • / What is the trick about starting a two cycle engine that sat for too long
primerbulb120 said:
Bad plug has 3 symptoms on 2 stroke engines as far as I know:

1. Won't start at all
2. Starts but runs rough
3. Starts cold and runs just fine till you turn it off, but then it won't restart till it cools down again.

Old spark plugs that have sat for a while should be replaced. In my experience they typically work the first few times then quit unexpectedly while you're using the machine.
Click to expand...

Are any of these conditions diagnoseable by running the spark plug outside of the engine?
 
primerbulb120

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  • / What is the trick about starting a two cycle engine that sat for too long
c5vettster said:
Are any of these conditions diagnoseable by running the spark plug outside of the engine?
Click to expand...

I've never tried. I have plenty of spark plugs laying around and I can put in a new one if I think the old one is bad. :laughing:

Pull the muffler and see if it will start without it. I've come across several with clogged mufflers, either from carbon deposits or from insect nests. One, a Poulan Pro blower, wouldn't even cough with starting fluid but once I pulled the muffler it started and ran great. (Probably annoyed all the neighbors though, so I let the muffler soak in carb cleaner for half an hour, then let it dry and reinstalled it.)
 
RDA.Lawns

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  • / What is the trick about starting a two cycle engine that sat for too long
a spark plug won't cost more than 5$ why are you trying so hard not to replace it and eliminate that possibility of a bad spark plug
 
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c5vettster

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  • / What is the trick about starting a two cycle engine that sat for too long
RDA.Lawns said:
a spark plug won't cost more than 5$ why are you trying so hard not to replace it and eliminate that possibility of a bad spark plug
Click to expand...

Good point. I am sure I probably even have one in a bucket somewhere. I know that some of these can be quite specific. Looks like this one takes the Y variety. I will stop by walmart today to try it out. It is nearly freezing outside and my shop is not heated, so may have to leave it till it warms up a trifle.
 
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