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Choke setting


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Ct hard to start lately takes several tries, pulled cowl and noticed one choke was not fulled closed

when trying to start, other was against stop, one carb.about 3mm from closing, how much difference would

that make starting? I did set it to fully close and it did start second try. thanks

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If you have any questions give me a call anytime.


3mm (about 1/16") either way shouldn't be a big problem. You said fully closed on start. Did you mean fully open? Choke should be engaged on first start of the day or later in the day if it sits all day. If you have a really low idle rpm then I would use full choke and crack the throttle about 1/4". If you have a high idle don't crack the throttle. After first start then I usually leave the choke off and just crack the throttle 1/4".


If the choke is sticking make sure you have a tiny amount of slack in the cable so it can completely close. If you have some slack and it still hangs up a tad then remove the choke off the side of the carb. Push the choke stem out of its body. Then use a scotchbrite pad and smooth down the edges around the choke outside edge and do the same for the inside of the choke body edge. Sometimes these get a tad of corrosion and are rough on the edges making them not moving free enough. Be careful taking the choke body off the carb to not break the choke fiber gasket. It is thin.


A bad idle and choke setup with bad throttle use can make starting an issue. I have never had a hard starting Rotax when setup properly and the owner uses good starting practices.

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Best terminology might be "choke" ON or OFF. Open and closed can be ambiguous as a carryover from real chokes that restrict airflow. Ours are seperate circuits in the carbs.


That said, I've had issues getting both chokes to go all the way off against their stops when adjusted to be full on at the other extreme. You might recall last time it was friction from a broken 90° elbow, but even without that everything has to be "just so" for it to work right.


In my layman's opinion, the return springs are a bit marginal, even when new. And I've replaced a few that seemed "tired". Yes, they're adequate if everything is perfect, but how often is everything perfect?


Admittedly, my plane has a much longer cable run from the control in the cockpit, opening the door to more friction in the system.


Anyway, being Experimental, next time the cowling's off I may experiment with slightly stronger return springs. Should not be necessary, and may mask other issues, but I'd like a little more "oomph" to them and don't see much of a downside.

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