This is how you set the low speed first always ck the manual to get a starting place for the low and high speed needle then run the engine up to operating temp and then bring it back to a idle let it run for 5or 10 sec then pinch off the fuel line (you do not have to let it Quit just unpinch the fuel line and it should keep running). The rpm should increase a little and then quit if the rpm increases alot you are too rich and the low speed needle needs to be screwed in I use 1/8 of a turn increment. If the engine just quits with no noticeable increase then you are too lean and you need to screw the low speed needle out When you are adjusting the needle sometimes you have to increase the throttle so that the engine does not quit when you turn the low speed needle. The other thing that I have not mentioned about idle is that it is very important to have a rock solid linkage If you need a consistent low speed idle. if you would like to know how I set up a throttle linkage let me know and I will take a pick or two and send them to you.
when you are done with the low speed needle reset the high speed and go flying!!!!


if you are using a composite prop it should idle for minutes without quiting