idle jumps rpm's without throttle

zingshoen · 02-17-2014, 07:19 PM

sounds like multiple problems! is the carb actually clean? did you blow compressed air through all the passages, and did you get a flow of air through them?
also check that the choke operates the way you think it does and that the slider isn t stuck. and make sure you get free flow out of the petcock.

if all that is okay, i would check the idle mix screw, it may not let enough fuel through. that explains why you need the choke to start, and then you get surges coz you have too much air and too little fuel, which results in backfiring. don t let the motor run for long that way, it s way too lean.

02-17-2014, 07:19 PM	#2
zingshoen Join Date: Jun 2009 Location: Brisbane, Queensland, Australia Posts: 648	sounds like multiple problems! is the carb actually clean? did you blow compressed air through all the passages, and did you get a flow of air through them? also check that the choke operates the way you think it does and that the slider isn t stuck. and make sure you get free flow out of the petcock. if all that is okay, i would check the idle mix screw, it may not let enough fuel through. that explains why you need the choke to start, and then you get surges coz you have too much air and too little fuel, which results in backfiring. don t let the motor run for long that way, it s way too lean. __________________ 1971 Garelli Gulp 50cc with open ports and 16 mm Bing Carbie + 1980 Honda XL 223 ZS + 2007 Zongshen LZX200G + DR400SM
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