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50cc Scooter won't rev up, Keihin PD18J carb

I can get it to start and idle but - opening the throttle makes is cough and miss, - and it doesn't rev up, - and it doesn't get better after warmup Out of the box, it wouldn't idle (just died), but with careful throttle control I could start it and was able to ride for 5 minutes, coaxing the rpm's up to cruising speed. I increased the idle stop screw until it would keep running. - after a while, ti would not rev up at all, just would cough and miss. - "choking" the air intake makes it die, leading me to believe it may be running rich - no idle or high speed jets to adjust - main jet #82, idle jet #33 - passages and jets appear clean and clear - main CV needle has only one clip position, nothing to adjust there - CV slide moves by hand - lots of fuel in the bowl, vent line drains fuel when carb is tilted over - accelerator pump works (I see the jet of fuel) - maybe the auto choke is not closing? But problem is present warm or hot. What can I test on a CV carb (I'm a CV noobie)? - hand-choking? - observing if the CV slide rises when the throttle is opened? What can I adjust? - jet sizes - idle stop screw Thanks, /John

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  • John Moore Jul 28, 2012

    No solutions? Here's a movie of the scooter idling, then dying when I try to rev it uphttps://www.dropbox.com/s/rovxuufpnlxzcx...

  • John Moore Jul 29, 2012

    More Test Results: The automatic choke seems to be operating normally. It is getting hot after idling for 5 minutes and when removed from the carb it is definitely extended, perhaps a 10th of an inch. The spark plug is soot black, indicating richness. Squirting gas or starter fluid into the carb makes the engine die. Holding the slide open does not affect idle and does not help the engine to rev when opening the throttle (it will still die).

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My 50cc scooter will idle at first and rev very well but wont idle what can this be

Posted on Mar 13, 2014

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6 Suggested Answers

6ya6ya

6ya staff

  • 2 Answers

SOURCE:

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Posted on Jan 02, 2017

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Z Laws

  • 375 Answers

SOURCE: I need tuning specs for my 1982 suzuki gs 750.

You need to fix the fueling first - without fuel it won't run!
Your other problem sounds like an air leak - either the manifold or the carb. Check by spraying WD-40 or CRC at the manifold and carb join while the bike is running - if the revs change (either up or down) you have a leak.

Posted on Jun 29, 2009

rockitman187

Randy Hough

  • 2559 Answers

SOURCE: XR 100 didnt move for a year.My bad so i cleaned

First Make sure you have all new fresh gas,and new fuel filter,Then check the intake tube between the head and carb for cracks or leaks,And You'll need to go back through the carb again as this is a carb issue,But without doing the above first,a clean carb won't be clean for long.

Posted on May 17, 2009

Anonymous

  • 1066 Answers

SOURCE: 02 Vmax Idels on choke will no idel or advance

you have a fuel delivery problem...have you tried a carb cleaner?  You may need to remove and rebuild the carbs.

Posted on Apr 11, 2009

Anonymous

  • 125 Answers

SOURCE: idles but won`t accelerate

Change fuel filter.
fuel pump sounds fine.
Check for kinked or blocked lines.
If it has a fuel recovery cannister service it.

Posted on Jun 15, 2009

luckyluke78

David Parker

  • 333 Answers

SOURCE: idles fine with or without choke - cannot

Few suggestions(if not checked already):
Holed or incorrectly seated diaphram?
Timing advance?
I Presume you have checked already the air correction and needle jets too.

Please get back to me if you require further asssistance.

Posted on May 27, 2010

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For more information about your issue please click on the blue links below. Good luck and have a wonderful day.
How To Fix 5 Common Bike Issues RideApart
http://www.thegsresources.com/_forum/showthread.php?181491-Bike-in-idle-and-rpm-s-go-up-and-down-then-stall
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