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joel_bc

Two-cycle engine questions

joel_bc
18 years ago

These questions pertain to the kind of one-cylinder, two-cycle engines that typically run chainsaws, brush cutters, etc.

1. What carburetor-setting refinement overcomes a *hesitation* to immediately accelerate when the throttle is opened (trigger pulled)? (Please assume the carburetor and air filter are clean, the fuel is mixed properly, the fuel line and its filter are in good condition, etc.)

2. What causes "dieseling" (the tendency for the engine to continue to run after the ground or "off" switch is closed to ground out the magneto)?

3. Why do small-engine mechanics typically replace the spark plug when a machine goes into the shop - rather than just gap it and clean any undue carbon or oil off of it? (What can normally go wrong with something as simple as a spark plug?)

I'm sure these questions are basic, but bear with me. I'd like to get a solid grasp on these things. Thanks.

Joel

Comments (11)

  • ruthieg__tx
    18 years ago

    Joel...seeif anyone at this forum can help you...

    Here is a link that might be useful: Farmlife

  • Tsavah
    18 years ago

    Hmmm ... May 3 was a while back already. Just in case another person reads this, small engines tend to have a very fine mesh fuel screen in the tiny carburator. This tiny screen is the cause of many of the symptoms you speak of, and not easily removed and cleaned without damages. Keep in mind we are talking about a tiny carburator system most of us cannot inspect without a magnifier and "young" eyes. As to why the sparkplug is always replaced; old habit that is worth a few bucks to the mechanic. Besides, they are kind of cheap normally and avoid a lot of issues, or problems that might develop about 10 minutes after you get the machine home. The mechanic is thinking; Why take the chance with the old one?

    In any case, if you are serious about wanting to learn all you can about small engines, you want to give the local Voc Ed (now called Tech Centers) class/shop some serious thought. Normally the instructor has a lot of years of experience behind him or her when one speaks with the golden tongue for only a few coins of the empire from your pocket.

    If an adult, you might want to try out the night class for adults, and see if more training is desired later or not. One advantage most adult classes have over the day classes for high school students is you are required (more or less) to bring something in to work on, but the shop instructor can help with this also. You will be surprised how much you will learn without realizing you did. Needless to say the instruction pays for itself as a few years and projects pass successfully towards "repaired" by your hands.

  • jack27
    18 years ago

    my stihl 009L chainsaw won't start, I believe it's not getting enough spark, it's yellow looking instead of bright blue, the plug is new but the plug wire is orginal it's cracked and the end that clipps on plug is coming off. How do I change this wire or what all do I have to buy and change. Help Jack Sayre

  • brit101
    18 years ago

    Jack (the thread hyjacker:o))a good place to ask this question is at the tool forum here, or the best website for chain saw questions is www.arboristsite.com go to the chainsaw forum. Not being familiar with Stihl saws, quite certain the ignition wire is attached to the coil. It may be listed for sale at www.mfgsupply.com or www.chainsawparts.com same firm. However if you post your question at the arboristsite.com you will get a far better answer than I have given. There is a repair manual for chain saws called chain saws at www.themotorbookstore.com and the 009 is in the manual.

    Usually the distance between the coil and flywheel is that of a business card, but ask at Arboristsite.

    If your saw won't start it may be caused by stale fuel, put in a fresh mix of gas and oil. May be the air filter, and may be the carb is out of adj. If the saw is older it may be in need of a carb kit, especially if it has sat for a while with fuel in the carb, months.

    Good luck.

  • brucer
    18 years ago

    I volunteered to fix a friends tecumseh 3hp two cycle S-blower, it won't start.

    I put fuel in cylinder an expected it to fire as I saw good spark, but NOoooo, just some very non-deterministic pops.

    So I pulled off the flywheel cover and plug. I put a wooden stick in spark plug hole to note TDC. I rotated engine and noted that the plug ONLY fires when the piston is a BDC! (bottom dead center). It is like it is 180 deg out of timing phase. There is a key on the crank for the Flywheel, also a funky key adapter on the crank. The flywheel uses a bigger keyway, and the adapter adapts it to the smaller crank key.

    I'm really stumped as with the keys the timing is hard set. I can't see how I could be 180deg out of phase, unless it is the wrong fly wheel.

    When I took apart the carb , I noted that the float valve was missing. My friend told me that he never touched it, but finally owned that he took the carb apart, but the wrong flywheel?

    bsemanchik@yahoo.com

    BRuce

  • samweldon
    16 years ago

    I've been having some trouble with my weed eater this year. The service company tells me oil gas mixture becomes old after 30 days and will cause trouble. I use my weed eater to cut the grass around my house, fence, and flower beds where the mower cannot cut. It takes me three months to use a gallon of gas oil mixture. If this 30 day rule applies I have to mix new gas oil every month. Is this 30 day rule correct and if it is where can I buy oil to mix half gallon at a time? Thank you.

  • suzi51
    15 years ago

    I have a 10 yr. old 2 cycle Ryobi string trimmer which was $200 new.
    It was used very little in those years. It was drained of fuel and stored for 2 years.
    A friend replaced the primer bulb and fuel lines, as they were cracked. It takes sometime to get it running and then it quits. I hate to give up and I
    realize I can buy a new 4 cycle one for under $100. A small engine repair
    person wants anywhere from $35-45 to either fix it or tell me it's trash.

    Any suggestions as to what I personally could try?
    Thanks

  • sirk
    13 years ago

    why do I have gas coming out of my muffler??
    the lawn mower runs fine, but when it sits
    in the garage gas drips from the muffler
    and almost empties my gas tank

  • cgilbert11_MSN_COM
    13 years ago

    what do the marking on a chainsaw carb stand for L H AND T

  • janbriggs52_gmail_com
    13 years ago

    Before anything is said i am a beginner in this field. Termenology is not known. I am in need of knowledge of how to fix my troybilt tiller. Spark plug wire is very old cracked end is not on good won't stay started .Had a clinton engine replaced that. found this tiller at a garage sale. on a fixed income so in need of home repair thanks for your help Janet

  • oregonwoodsmoke
    13 years ago

    For 2 cycle engines, you will save yourself a lot of trouble if you only use ethanol free gasoline.

    There should be one station in your area that sells it. It is illegal to put it into cars, but you can buy it for small engines by taking in a gas can.

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