Plug Picture...Lean or Rich?

Discussion in 'Motorized Bicycle General Discussion' started by WaterDog, Oct 12, 2010.

  1. WaterDog

    WaterDog New Member

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    Put in a brand new Champion plug gapped at .30. Took it out for 15 minutes, half at medium speed and half at open throttle. I am still breaking in the bike and have maybe 75 miles on it. I am using synthetic oil at 25:1. Does the plug look bad after just 15 minutes, or should I just chill until the break in period is over. Runs and idles great, but does seem to choke out at little over 90% of throttle. Thanks guys!!
     

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  2. muddybike

    muddybike New Member

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    Im new but to me that looks lean , i was under the assumption that a light chocolate tan was the color that your shooting for ...

    Dont take my word tho , wait for others to chime in!
     
  3. Slowrollers

    Slowrollers New Member

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  4. Dave31

    Dave31 Moderator
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    Yes lean, last pic looks better but still a little lean for my comfort.
     
  5. Mind_Reader7

    Mind_Reader7 New Member

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    Nice way of remembering it according to that site.
     
  6. WaterDog

    WaterDog New Member

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    Thanks guys..so one cause of running lean could be an air leak on the engine side of the carb, correct? I'm sure there are many causes, but that's the easiest for me to check.
     
  7. Slowrollers

    Slowrollers New Member

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    Check for airleaks with carb cleaner....Spray it around the intake and carb first.if the motor revs high or dies BINGO! If not start checking the base gasket & head gasket.... If Not there then go spraying on the case halfs......
     
  8. Creative Engineering

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    15 minutes run-time...your plug looks perfect to me.

    Jim
     
  9. Kevlarr

    Kevlarr New Member

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    Something I've found that's a little more paint friendly then carb cleaner to check for air leaks is glass cleaner (spray bottle on the stream setting), it works just as well and instead of eating the paint on your engine you clean it. :D
     
  10. Slowrollers

    Slowrollers New Member

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    Ive also used keyboard duster(Dustoff) it works but not as well as carb cleaner......I have two black painted motors and carb cleaner has never harmed them.....
     
  11. bairdco

    bairdco a guy who makes cool bikes

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    i agree with Jim above. 15 minutes on a new plug isn't enough time to get an accurate reading. try riding it for a few hours at least, vary the throttle, and do a "plug chop" as suggested so you don't just dump raw fuel on it when you shut it off.
     
  12. corgi1

    corgi1 New Member

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    If you pull the plug w/ the motor hot will the threads come out ?.
    and on the lighter side,if you check the plug this way every 5 miles wont that be cost prohibitive?




    lol
     
  13. Goldy

    Goldy New Member

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    For only 15 minutes running it looks fine, but I completely agree with Jim and Bairdco that this isn't long enough of a run to get a good reading.
     
  14. Dave31

    Dave31 Moderator
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    Wow, I must be doing it wrong, I run mine less then 2 minutes when jetting.
     
  15. Dave31

    Dave31 Moderator
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    Okay about 12 minutes to do 2 runs and change the jet...

    1st photo is the first run about 700-800'

    2nd photo 2nd run Changed to a bigger jet to richen it, and again about 700-800'

    Of course I did not add the time to warm the motor up.

    You can clearly see what a difference the jet made in such a short run, so I dont know?
     

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  16. Goldy

    Goldy New Member

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    First plug looks perfect, how about you just leave it running with that jet for a while and see what happens?...these little engines are working their guts out (like a chain saw engine), so you might not have to wait as long to get a decent reading. Second plug is definitely running rich if it got sooty that soon.
     
  17. bairdco

    bairdco a guy who makes cool bikes

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    you may be right, Dave. i was thinking with a newer engine and a rich oil mixture, it'd take a little longer than 15 minutes before it got all gunked up and turned black.

    on a tuned engine, a coupla blasts up and down the street would probably be enough to see what's up.
     
  18. Goat Herder

    Goat Herder Gutter Rider

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    SBP had said about the same thing in there pipe instructions as Dave did. That's about the way I always did it.
     

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