What is the recomended method for adjusting the needles on the DA-100? My engine runs very good thorough the transition and at top end, but idles very rough. Is the low needle too rich or to lean?

what is the rpm at idle

When I first drop to idle it is about 1350 but slowly goes uo to 1500.

ok I had the same problem, your to lean, you need to richen about a blade or 2 on the low end

You may also have an airleak somewhere. Does the engine at idle load up and quit or does it just go up and down in rpm?

Thanks, I thought it might be lean. I have had this engine for about six years, but only about 450 flights, and just recently have had issues with it. We got it running very well a week ago but had to richen the top end about a half turn. It was recomended that I rebuild the carb, which I did. Should I adjust the top end for max RPM, as recomended by DA, first? I have prety much run the engine at da's recomended settings in the past. I am at sea level.

Keith Bentley

with any oil mix engine you set for max rpm and then richen it up to drop some rpm........just a little,
When I talked to Jeff at DA, I told him that when I take off the rpm was at 1200 and when I landed it was over 1500 he told me I was to lean on the low end, but my engine is brand new.

Wood would have some good knowlage of that engine I'm sure, being an engine with that much time on it, it could be an air leak.

You need to get the low end set first before setting the high.

Thanks for the response. I will try tomorrow.

AJ I thought the low end needed to be set first? back to drawing board.
The manual does say to set the high end first, right?????

sorry I thuoght the high end was first

When I first had problems with the engine, I sent it to DA. They said that the carb block was lose and fixed it. I just checked the carb gasket when I rebuilt the carb and it looked good. I don't know where else there could be an air leak, but suggestions would be appreciated.

Originally Posted by WOODisGOOD

You need to get the low end set first before setting the high.

This interest me too.Are you referring to setting needle on low side to approx 5/8 out then set high needle to max rpm?

Carb needles 101
ALL gasser carbs work EXACTLY the same...
There are differing opinions on how to set the needles....
There is NO such thing as a "Factory" correct needle setting...Different props, atltiude, fuel mix all affect the needle setting.
Both needles affect the high setting..
Open both needles 2 turns.....Set the high for max rpm...
Use a tach, set the idle speed to about 1800 rpm....Slowly lean out the low needle...the rpm will increase...Re set the speed to 1800....Lean the low needle again, if the rpm increases slow it down to 1800...Keep doing this until the idle speed no longer increases....Try the transition, it will probably die...Open the low needle slightly until the transition is good...Go back and re set the high for max rpm, then richen it slightly....Fly....The low needle might need re adjusting to allow for how it reacts in flight....
The " FACTORY" SETTING CAN'T POSSIBLY WORK FOR EVERY ALTITUDE AND PROP SIZE....iF IT WORKS PERFECTLY FOR Y0U, CONGRATULATIONS, YOU GOT LUCKY...
DA might be the world's greatest engine company, even they don't have ESP...
If your carb has not been rebuilt for a few years the diaphragms are getting stiff and not working the same as they were when new...A diaphragm kit is about $5 from a small engine shop....
Old diaphragms WILL affect the operation and needle settings....