ORIGINAL: 1080tommy
Advanced the throttle quickly to 2500-3500 and this is were the thing just does not seem right. It was hesitating and the manual said this was a lean condition and to richen the mixture 1/16 of a turn until there was a smooth idle and good transition to midrange. I either get a higher then normal idle or an idle that barley keeps the plane running. It seems like if I reduce the throttle trim by 1 click the idle drops too low. I removed the new plug and it is black so I think it is rich but if I lean it there is a hesitation when I advance the throttle to full. Any ideas on how you guys set your mixtures would be greatly appreciated.
Tom
Start with the factory needle settings whatever that might be. Will it idle for 20 or 30 seconds without dieing? If so go to WOT for 5 seconds or so then back to idle. When at WOT was it burbling or a clean 2-stroke sound? If it had a slight burble to it, put it in the air and fly it a flight. Does it burble at WOT straight and level flight? If so, land and take the HS needle in 1/12th turn. Fly again. What's it sound like:??? Still got a burble? Take the HS needle in another 1/12th turn. Once you get it to where the burble is gone at WOT in level flight, now work on the midrange a bit with the low needle. Is it really sloppy rich at idle and say up to 3500 rpm? If so take the LS needle in a 1/12th turn.. Fly it again.... You'll never get all the burble out at idle. If you do, odds are you are too lean. Also when you lean the LS needle, you have leaned the WOT mixture a tad. It maybe necessary to go back and open the HS a hair if you close the low very much. Most the time if you're not on the ragged edge of being lean at WOT, it won't be necessary thought. I may catch flack for this, but I never use my tach to set the needles on my gassers. These things change in flight, so you might as well learn to set them by ear and what the spark plug looks like after several gallons. Also don't run at WOT on the ground for more than 5 or 10 seconds...they can over heat in a heart beat.
On the idle trim movement. Gassers can be kind of fickle like that. On my Futaba 8 UAFS transmitter, I can go into the progamming and change the amout of servo movement I get for each "beep" of trim. I can really fine tune it that way......
When testing the throttle from idle to WOT on the ground. Do it like you would when you are flying. How often do you go from idle to WOT in .005 seconds when you fly?????? I've seen some gassers with the carb's set right, that still won't take the fuel when flipping the throttle stick like that....if you try to set the carb to where it will, it won't be right in the air.
Also for a filter in your fuel tank, I use the felt clunk type filters that's used in chainsaws and weedies...I've yet to get even one piece of crap on the screen in the carb.