Plug Picture...Lean or Rich?

WaterDog

WaterDog

New Member
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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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!
 
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.
 
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......
 
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
 
Kevlarr said:
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
Click to expand...


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.....
 
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.
 
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
 
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.
 
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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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.
 
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.
 
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