In Reply to: 9N motor posted by Carroll Amick on June 15, 2013 at 09:22:04:
Sounds to me like the fuel to air mixture is too rich. Start tractor and let it warm up for 3-5 minutes. With engine at idle, throw throttle to wide open (WOT)then back to idle. Adjust hi speed jet in about 1/4 turn (clockwise). Do idle to wOT again. If it does not stumble, turn jet another 1/8 turn. Do WOT again. If no stumble, turn jet another 1/8 turn. When a WOT gets a stumble, back jet off a bit until a WOT does not stumble.
Also, a lot of start-ups without warmups will foul plugs. The fuel we buy today is not kind to these old engines. hth
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