Discussion in '2-Stroke Engines' started by geebt48cc, Jan 20, 2012.

  1. geebt48cc

    geebt48cc Member


    66cc is running very well at 400 miles. I've been checking plug, and its been right in the zone of chocolate color. Well, today I took bike out for a few, and it did great as always. I looked at plug, and it was white????????????

    Strange, not any air leaks? Running perfect? Go figure?????????????/


  2. jaguar

    jaguar Well-Known Member

    gas and oil the same? could be some trash in the carb causing it to run lean. clean that jet.
  3. geebt48cc

    geebt48cc Member

    .......Jag, you're a good man. I'll check jet.........I've just got a $3 dollar inline filter on it. That's about the only thing that it could be sense it runs like it always has?
  4. jaguar

    jaguar Well-Known Member

    pull the fuel line off the carb and turn the fuel petcock to the on position and check for a meager flow (normal). If it is a pitiful dribble then its either the filter or the in-tank petcock filter which can at least be temporarily cleaned by blowing into the line.
    but trust me you did seize it and there is unwanted aluminum from the piston stuck to the inside of the cylinder. done it many times.
  5. geebt48cc

    geebt48cc Member

    Jag, are you saying that the motor seized without me even knowing it? Wouldn't I had been able to feel or hear something if that had happened to motor when riding? See, I just by chance chopped plug, and then saw that it was very white. The bike ran and runs like it always has when plug has always been a nice chocolate color, but after this few mile run this time, bike ran as normal, but plug was white ?

    I'll do what you said.............

  6. jaguar

    jaguar Well-Known Member

    oops! I got crossed on threads and thought yours was the one where the guy seized. sorry
  7. geebt48cc

    geebt48cc Member

    No, No, Jag, don't worry .............(ALL is good) Jag, it would be so very eas\y to do that when you answer so many of these randon questions on these HT's.

    ...........Hey, keep up the great work you do............

  8. geebt48cc

    geebt48cc Member

    Jag, I took bowl off, blew/cleaned jet and buttoned back up. Took out 3/miles, and came back to chop plug and found it was a perfect white??? ****? Like I said, it's been chocolate colored all summer, but now still runs the same, but with white plug? Needle is set 4th down from top flat,25:1? Looks like it would be on rich side?? It does not rev high/when off throttle, and idles great.............Confuzed here?

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    Last edited: Jan 22, 2012
  9. toojung2die

    toojung2die Member

    It's hard to see in your album photos but it looks like you have clear fuel line and an in-line filter. As long as there's fuel in the line on top of the carb your tank isn't starving the carb for fuel. Try a larger jet and plug chop. With a small drill index and solder re-jetting is quick and easy. Can you get it four-stroke with partial choke on? It looks like you're running on the lean side of a good fuel/air mixture. Not lean enough to bog at high rpm but lean anyway. You want to run a little on the rich side of good fuel/air mixture for sufficient lubrication. Expansion chambers cause leaning out.
  10. geebt48cc

    geebt48cc Member

    Thanks Jon, appreciate the ideas. Well, when I first started playing with these bikes I used clear fuel line, but using 1/4 rubber line now. Uno, everything is true what your saying about the bigger jet size, but what I don't understand is how it changed from being a good chocolate color all summer to white now? I've gone over every possibility, and all is well? The only thing I've done is gone from a 50:1 mix, to a now 25:1 mix. See, I changed mixing ratio because I've read so much about how people wish they had used a thicker mix. So, I am switching now back to forever 25:1. I'm still using Amsoil Dominater synthetic. I know that's pretty thick for synthetic, but remember it's from China.

    I wonder if that had anything to change burn from chocolate to white? You would think that it would become darker being richer? Go figure????
  11. toojung2die

    toojung2die Member

    Don't know about synthetics, still using dino oil. Hopefully someone with experience will pop in and say they burn cleaner and that accounts for the plug color change. I assume you've already eliminated the possibility of air leaks? Those can develop over time.
  12. geebt48cc

    geebt48cc Member

    Yes Jon..........I've really gone over everything. Jon, See, I've been running the synthetic for 200 miles +............Total miles now is 410 miles, and really runs about as good as it ever has, but always chop plug after each ride, and that baby was all white?????..........it's always been s nice chocolate tan color. So?.........somethings going on?

    These engines are so fragile anyway.......WHITE is sure death?
  13. HeadSmess

    HeadSmess Well-Known Member

    no. white can be a sign of the correct heat range plug doing its job and self-cleaning.

    blistered white...now thats a problem... or melting electrodes. by which point the pre detonation is so bad it wont run anymore...been there :)

    dont confuse uneven carbon on the insulator nose to be blistering :)

    changed oil ratio recently...or brand... even fuel type.

    or even ran it for longer than normal before chopping so the plug can get hot?

    and then finally...chopping with the killswitch at WOT every time?
  14. geebt48cc

    geebt48cc Member

    HS, appreciate you saying that, because I've really picked this bike apart trying to figure out why over night the plug would turn white? After every run I chop plug to stay on top of its burn. I even took head off and found that everything on top of piston is like new again. I've never heard of the self cleaning process, but I just want everything to be getting as much lube as it can get, and still run optimally correct. The only thing I did, was not changing make of oil, but the mix from a 50:1, to a 25:1. The plug NGK B6 plug.
    Last edited: Jan 23, 2012
  15. HeadSmess

    HeadSmess Well-Known Member

    the self cleaning effect is the main reason plugs have heat ranges.

    some engines get hot, and can clean a cold range plug, while a hot plug in the same engine will overheat and melt.

    low performance engines run colder, richer, and create more carbon, and 2 strokes have the oil to contend with. a cold range plug turns black and fouls up, a hot plug will clean itself... too hot and again, melting with bad results :)

    the heat range does not affect the spark temperature! its just the "operating temp" of the plug in question.

    the oil ratio...you went from 50 to 25? not the other way round? ok, now thats weird.

    but then, adding more oil makes a leaner mix as the jet can only flow so much...adding oil reduces the amount of fuel...

    stop worrying! :D

    my first mb had a husquvarna brushcutter. it was standardly tan after doing a chop. i then did a 200km run in one go, wot all the way :) plug looked like it had just come from the box! and at night you could actually SEE the insulator glowing blue! (very translucent ceramic?)so the mixture was spot on :)

    it was when i ran out of cash and started running with mixes of kero and other flammable products that it died :jester:
  16. geebt48cc

    geebt48cc Member

    HS, that makes sense. Uno, the reason that I went from 50:1 to 25:1 is due to all the horra stories that I do hear on these little china engines!~ See, that was the whole point of switching back from a lighter mix, to this 25:1 (even though it's synthetic). Also, what makes it harder to understand?

    I ran 25:1 when I was first breaking this motor in. Plug then was a great chocolate color, and now with the same mix 300 miles more; the top strap and electrode are white on NGK B6.............Same plug I've always used.

    PS- It's on 3rd notch on E-clip. So, in all thats said here, I wonder if I should set it leaner to 2nd notch like it came out of box?
    Last edited: Jan 23, 2012
  17. ddesens

    ddesens Member

    Try an experiment and run some fuel mixed at 50:1 again and see if the plug color changes. Realistically your not going to do it any harm. Just my opinion.
  18. geebt48cc

    geebt48cc Member

    Guess I could try that........... I took out for about 7 miles today. Bike idled well, no bogging or reving when off throttle ,cruised at 25, topped at 32...........I got home, it cooled off, chopped plug, and it was solid white/electrod/strap of plug and base ring also??????????? Uno it was set on richest needle setting!~(Bottom of needle/pointed end)

    ............If I ride much like that, it will kill engine!!!!!!!!!!!!~
  19. HeadSmess

    HeadSmess Well-Known Member


    i believe youre describing "normal", "ash deposits" or "worn out"

    clean it, replace it...and stop worrying!

    also, wont hurt to go smaller on the jet ;)

    the one to worry about is that "overheated" one...
    Last edited: Jan 25, 2012
  20. jaguar

    jaguar Well-Known Member

    50:1 is 2% oil, 98% fuel
    25:1 is 4% oil, 96% fuel
    Not a big difference but still it is a bit leaner now than before.
    I would buy a micro drill bit set and drill out the main jet to the next larger size.
    With the standard CDI that comes with these engines it is not hard to seize them since the ignition timing is way too advanced at top rpm's.
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