Blowin Smoke
Scoot Enthusiast
Posts: 289
Location: Port Orange, Fl
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Post by Blowin Smoke on Oct 24, 2014 8:00:51 GMT -5
I have a qmb 139 that run irradically. Won't idle, low on power, when it dies it won't start for a few minutes like something has to cool off. I replaced the carb with an adjustable one and it didn't make any difference. I am leaning towards a coil being bad. Any advice would be greatly appreciated.
Thanks,
Pete
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Post by stevec on Oct 24, 2014 9:35:37 GMT -5
if it is a 4 stroke check the valve adjustment.
could be a CDI on the way out or a coil, could also be a vacuum leak.
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Blowin Smoke
Scoot Enthusiast
Posts: 289
Location: Port Orange, Fl
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Post by Blowin Smoke on Oct 24, 2014 10:26:24 GMT -5
Adjusted the valves and checked for vacuum leaks. Seems to be weak spark at low rpms after looking at my spark tester and looking at the plug out of the engine while cranking. Replaced the plug in the early stages. If you were a betting man what would you do/replace next?
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Post by katastroff on Oct 24, 2014 11:16:30 GMT -5
Compression
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Post by stevec on Oct 24, 2014 16:28:56 GMT -5
only 3 components, coil, CDI and stator/pickup, if it is weak spark the coil is the first thing i would check, i always keep a spare coil and CDI handy for troubleshooting.
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Post by niz76 on Oct 24, 2014 17:04:03 GMT -5
I have a qmb 139 that run irradically. Won't idle, low on power, when it dies it won't start for a few minutes like something has to cool off. I replaced the carb with an adjustable one and it didn't make any difference. I am leaning towards a coil being bad. Any advice would be greatly appreciated. Thanks, Pete Maybe idle circuit is lean? You could be experiencing a soft seize and when it cools down it'll start back up... just some ides. Try screwing the Air/Fuel screw all the way in (rich). does it still idle? |
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Blowin Smoke
Scoot Enthusiast
Posts: 289
Location: Port Orange, Fl
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Post by Blowin Smoke on Oct 24, 2014 17:15:12 GMT -5
Swapped the coil and no luck. My buddy thinks I should replace the stator. What do you guys think?
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Post by scooterpimp on Oct 24, 2014 17:59:13 GMT -5
How many miles on scoot? if it is spark loss is your cdi ac or dc? Will it fire on starting fluid etc. When acting up?
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Post by Corrosion on Oct 24, 2014 18:03:03 GMT -5
Change out the, Plug Cap.
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Blowin Smoke
Scoot Enthusiast
Posts: 289
Location: Port Orange, Fl
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Post by Blowin Smoke on Oct 24, 2014 19:45:18 GMT -5
Changed the spark cap and it will not fire with ether when it dies. If I wait 10 minutes it will fire.
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Post by niz76 on Oct 24, 2014 21:06:13 GMT -5
Good compression?
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Blowin Smoke
Scoot Enthusiast
Posts: 289
Location: Port Orange, Fl
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Post by Blowin Smoke on Oct 27, 2014 17:29:16 GMT -5
Replaced the stator and pick up today and that solved my problem. Lesson learned. Thanks for the help.
Pete
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Oct 27, 2014 20:05:08 GMT -5
Twice on this thread i have seen Compression asked about, and ignored. So I will ask also?
What does a properly done compression test say? If its too low, there is NOTHING you can do to make it run right intil the compression problem is addressed, if there is one.
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Oct 27, 2014 20:05:20 GMT -5
Twice on this thread i have seen Compression asked about, and ignored. So I will ask also
What does a properly done compression test say? If its too low, there is NOTHING you can do to make it run right intil the compression problem is addressed, if there is one.
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Blowin Smoke
Scoot Enthusiast
Posts: 289
Location: Port Orange, Fl
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Post by Blowin Smoke on Oct 29, 2014 20:48:14 GMT -5
1200Km on the scoot. Compression is not an issue when it runs at all. If it would not start and had spark that would have been in the diagnostics. Some times people people try to over think a problem and go on tangents. BTW, not my first rodeo.
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