Plug colour questions

Discussion in '2-Stroke Engines' started by nashy10, Sep 17, 2013.

  1. nashy10

    nashy10 Member

    I cant find an inbetween the plug being wet or black dry. This is the closest i can achieve by moving the needle.

    29288qv.jpg

    Just wondering if this will damage anything or what i could do.
     

  2. jaguar

    jaguar Well-Known Member

    Of primary importance is how it runs.
    Of secondary importance is the plug color (which is also influenced by type of oil used and at what ratio).
    I don't even look at my plug. That just gives a crude ballpark idea of what the engine is doing.
    But knowing what is "just right" is something that only experienced tuners know.
     
  3. jaguar

    jaguar Well-Known Member

    Of primary importance is how it runs.
    Of secondary importance is the plug color (which is also influenced by type of oil used and at what ratio).
    I don't even look at my plug. That just gives a crude ballpark idea of what the engine is doing.
    But knowing what is "just right" is something that only experienced tuners know.
     
  4. flashstar

    flashstar Member

    http://www.strappe.com/plugs.html

    Check out this link and read up on plug chops. I just did and was massively informed. I believe that the spark plug I posted in my thread indicates slightly retarded ignition timing. You are running your engine too rich since you have soot build-up. Try reading your plug's mixture ring where the porcelain meets the plug body.

    Jaguar,

    2 strokes are so touchy when it comes to fuel mixture and timing that a slightly lean mixture might produce a failure condition. I believe there is no substitute for a thorough plug reading.
     
  5. HeadSmess

    HeadSmess Well-Known Member

    the plug will only indicate that the mixture is right, if the temperature range of plug is right.

    otherwise youre chasing your tail.

    jet for max power and speed.

    plug for correct heat range.

    a cold plug will always tell you the motors too rich when it isnt.
    a hot plug will always tell you its too lean when it isnt.

    the motors performance alone will tell you when the mixture is spot on.
     
  6. jaguar

    jaguar Well-Known Member

    On my bike the difference in plug color between jetted perfectly to being jetted just a hair off is hardly noticable.
    Type of oil used and ratio used and plug heat range all affect color.
     
  7. flashstar

    flashstar Member

    Interesting. Do you think I should wait to change the fuel mixture until I install a plug of the correct heat range? I'm running a 5 at the moment and feel that it might be too hot so I am getting a 6 shipped in.

    Is it not true that a 2 stroke usually runs best right before it melts down?

    So as not to hijack this thread, do you think that the OP should switch to a hotter plug? That might be why his chops are always so black.
     
  8. jaguar

    jaguar Well-Known Member

    Best performance is close to dangerously being lean.
    What may be complicating things here is if you are using the standard carburetor which does not have a true idle circuit for good mixing of the fuel and air of the idle mixture. If that is the case then all I can say is "get a good carburetor"!
     
  9. HeadSmess

    HeadSmess Well-Known Member

    plugs are complex. run lpg and they wont change colour at all.

    two stroke will tend to rev out higher when lean, but will produce more power when ever so slightly rich, or a stoich ratio below "perfect". thats...14.3 from memory with petrol. or is that atmospheric pressure? maybe its 14.7... anyway. its about that :)

    noone ever says what the stoich is once oils added to the fuel, i just realised.

    looking at that black plug, yep, id say go hotter and by two numbers. overheating? i dont think thats ever going to be an issue with that plug.

    when the heat range is right, then yes...the plug IS a good indicator of whats going on inside while being easy to access.

    best to experiment with the standard Hs ngk plugs rather than the exotics at first... a full set of b**hIX would cost a fortune... luckily, 4 to 7 seem ideal...
     
  10. Fabian

    Fabian Well-Known Member

    needle adjustment has "no effect" on the air/fuel ratio when the carburettor is operating at 3/4 to full throttle.

    If you want an easy to set carburettor, it's best you get yourself a Rock Solid Engines reed valve intake with Walbro adapter and Walbro carburettor. These types of diaphragm carby use externally adjustable jetting screws; making it a simple process of finding perfection when setting the correct air/fuel ratio.
     
  11. IbedaYank

    IbedaYank Member

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