What Are Signs Or Symptoms That Spark Plugs In A Motorcycle Need To Be Changed

Posted in Ignition Systems | Asked on Jul 14, 2010

Will the motorcycle “chug” when at say 55 or 60 mile per hour? Could this be because of spark plugs, needing to be changed?

There are 8 Answers for "What Are Signs Or Symptoms That Spark Plugs In A Motorcycle Need To Be Changed"

  1. kelly_f_1999 says:

    is only a few bucks… so why not get new ones…. but its either that or bad gas or filter

  2. sleepydo says:

    chug sound like more fuel / air mixture problem than spark plug.

    bad plug is usually indicate hard to start and lower rpm problems than higher rpm.

    Plugs are cheap so it probably won’t hurt to replace them.

  3. David K says:

    It’s possible but you need to pull them and take a look. Plugs can be a wealth of info if you know how to read them…I won’t go into that here…you can research on line. Mileage is a good indicater of when plugs are finished… but you should pull from time to time and look. If a bike is running right the sign will be an erosion of the electrode. A good rule of thumb, as with oil and other preventive maintenance, is to know your tech and change things BEFORE you need to.

  4. Mike Q Girardot Colombia says:

    Could be, but also check your fuel filter, or injector it may be clogged, so the faster speed=more fuel being pumped in, it it gets “Chocked” sounds more like a carb/injector problem. if you want replace teh spark plug ($10) a set of 2, if it does not improve, then try a carburator/fuel injector cleaner (depending wich one your bike has) I had the same problem it was a dirty carb, I ran a carb cleaner and some spray directly into it, it worked.

    Hope it works, and ride safe.

    Michael.

  5. bryanjcohen says:

    There are several things that could hint at bad plugs.

    - Hard starting.
    - Slight to severe hesitation when you give the bike some throttle.
    - Stalling, especially when you give the throttle a good twist
    - uneven idling (tends to zoom up, or down, or sputters)
    - After running the bike for a little bit, take out one of the plugs. If the end of the plug is wet, its not firing, and it could be oil fouling the plug
    - take a look at the color of the end of the plug — if it is white, its running too hot, and it can cause misfires
    - look at the same area, and if it is covered in black soot, it can be poor gas mixture and dirt in your tank causing it to foul

    If the bike is chugging at highway speeds, it could be several things — carb hi-jet fouled, clogged fuel injectors, etc. But probably the easiest thing to do is just put in new plugs and see if it goes away. if it does and the problem comes back, look a little more upstream in your intake system (i.e., carb, fuel injector, spark plug wires, etc).

    Oh, and also make sure you are using spark plugs that are gapped properly and designed to run at the temperature that your engine requires.

  6. Magickman says:

    Yes, it will “chug” when the plugs are getting old or fouled. another thing is fuel mixture. A lean mix will also make the engine sputter at a given speed. Get a tune, and have your carbs looked at by your dealer.

  7. txmountain_biker says:

    old gas in the tank will make it feel like a bad plug or carb out of adjustment, always have fresh gas in your tank ;)

    a month or two old is ok

  8. bikinkawboy says:

    The most obvious symptom of worn or tired plugs is missing when you accellerate hard. They’ll run fine under light throttle but as soon as you crank open the throttle, miss, miss. miss. Be aware that with weak ignition systems, plugs can look good but be shot. Old 60′s-70′s bikes were known for weak, low power ignitions.

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