I have a small problem with my bme 37% ultimate with 110X bme. The is when the aircraft is in the air the throttle has a delay, when you pull the throttle back to idle it takes half to one second before it will return to idle + the transition up is slow also. On the ground, it is fine. Could it be the servo 577 JR standard or could it be a tuning problem? In addition, the engine runs ruff on take off it sound like it runs on one cylinder for a couple of seconds. Once it gets going it is fine plenty of power and no missing. Could this be ignition? I did here of some problems with the CH ignition system.

If it is FINE on the ground but having problems in the air, it almost is surely a pressure problem. Buy or make a fitting for the metering side of the carb and run a line from there into the fuse where the pressure should not be changing as much. BME makes these if you do not want to do it yourself.

You did set the needles, and are not running with factory settings are you?

thanks RTK. but i already have the BME one on there.

How much room do you have between the carb and the cowl, I once had to cut a hole below the carb, it was to close. It responded similarly to what you have explained.

Have you adjusted the needles also?

Did you run a line from the metering side into the fuse? and is the fuse not being pressurized somehow? If all else fails let the line dangle out the bottom of the cowl.

i have about half an inch between the carb and the cowl, no hole cut but there is a lage hole cut around the exhasust to let air out, i have no more holes cut then others have on theres, that i have seen on this forum. the tube is not in the fuse. it is facing back to the fuse but in the engine bay about 6 to 7 inches long.

I would try putting it in the fuse first, If that doesn't work cut a hole under the carb, it does not have to be that big.

By the way, have you adjusted your needles? Rich on high end and semi-lean but transition on low?

Maybe someone else has an Idea I have missed, I'm kinda tired and what I have said is just stuck in my mind.

RTK thanks for your input it all helps, the tuning could be the problem, or that is what I am hoping. You may have to go in to more detail on that one for me. As far, as air over the carb causing a vacuum or whatever. Most of the problem is more evident when I put the aircraft in a hover; you would think there would be no more airflow over the engine than there would be on the ground because it is stationary in the air.

John Leigh;
Throttle taking a long time to spool down rpms is an indication of too lean on the low speed adjustment needle. At least on my 2 110's

Haa. How far is the plane from you when you notice this! I notice this all the time. It's the additional time it take for the sound to get to you.
Bring the plane in nice and close (<30 yards) and see if you notice it! You would be supprised how close a 40% seems, yet still "hear" a big delay in throttle up & throttle down. It may be nothing....

A half inch may not be enough distance from the carb to the cowling. If I remember correctly my DA 100 manual recommends one and one half inch distance minimum.

A friend had this problem on a Sachs 4.2 in a biplane. He cut a one inch diameter hole in the cowling in line with the carb inlet and the problem went away.

fshnee-RCU how many turns out is your low needle? As far as the cowl causing the problem, is there anyone else that has cut a hole in there cowl on there 37% BME? For the aircraft been to far away, I no what you are saying but I can see the control surfaces moving without delay, rudder etc.

I really don't think it matters whether it's a twin or a single, if your carb is too close to the cowl and the engine is running funny then a hole may help. I had a lot of problems when I first started flying my Bücker Jungmeister with a Sachs 4.2. I really hated to cut a hole because of the non scale appearance. Putting the hole for the carb fixed all of the funny running problems. The engine always ran fine on the ground.

Ken

Ever so slightly less than 1 turn