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<DIV>It sounds like the low end is to rich try opening the low end needle about
a turn at a time, each time you do this reset the high end to Max rpm then back
it off about two or three clicks. Bring it down to idle say 2500 rpm hold at
that position for 30 seconds then go to full throttle. if it smokes and stutters
coming up it is still rich if it hesitates with little exhaust smoke it is to
lean if it is rich repeat the procedure and continue to lean out the low end by
opening the low end needle a little at a time. The first YS-140
sports had to small an opening in the low end carb barrel baffle
that required it to be drilled out to 1/8 inch diameter and caused similar
problems. Assuming all else is OK with the engine this should work I have had to
do this for several people who have had this problem and it worked every
time. Also the YS140 loves High Nitro fuel I am running Magnum-2 mine turns 9000
rpm on a good day with a 16x11 APC prop. Good luck</DIV>
<DIV>Buddy</DIV>
<DIV>PS. Some YS-140's require five turns out on the low end
needle.</DIV></FONT></BODY></HTML>