In last trip to the field, my da85 lost power. High RPM at 6000 with 27X10 CF prop. It used to reach 6400. The engine ran lean 3 minutes into the air.

Checked the in-line filter and the mesh screen in the carb: clean. There is no sign of leak around the carb gasket area.

Fuel is mixed with 35:1 Pennzoil Air Cooled.

This is second time it does this.

Please provide some clue on this as I start to loose confidence.

Plan to use the engine in a AW 75 Edge for an IMAC event.

What did you do to fix it the first time?

I sent it in. Da did a steam cleanup. Other than that, i do not know what has been done.

May just be hot weather getting to it?

Could be. It was 97 yesterday when I flew it. I flew at about the same weather before when the engine behaves.

I test ran today on ground and noticed the hign RPM did not pass 6000 regardless the adjustment on high and plow needles.

The trouble with a gas engine at such a state is that u have at least one week of downtime. The previous checkup with da was about a month ago. Too bad. Do not know if it is a norm for competition engines.

maybe u can tweak the needles a bit for the warmer weather and also ensure you servo is opening the throttle all the way when looking into the carb (motor off)

In the ground test, I opened up the high to 2 turns out from 1.5. For low needle, about 1/8 either way from 1.5.

Visually confirmed that the throttle plate can reach fully open position.

Normally I do not run the engine dry at the end of day. Wonder if the oil starts to deposit in the passages inside the carb. This could restrict the flow of the fuel and caused lean run. The plane is stored in gargage and the temperature can hit 100.

In the ground test, I opened up the high to 2 turns out from 1.5. For low needle, about 1/8 either way from 1.5.

Visually confirmed that the throttle plate can reach fully open position.

Normally I do not run the engine dry at the end of day. Wonder if the oil starts to deposit in the passages inside the carb. This could restrict the flow of the fuel and caused lean run. The plane is stored in garage and the temperature there can hit 100 in summer.

There are two DA 85's at the field where I fly, both get 6100 rpm on 26x10 Menz wood prop at 1200' ASL and 85F.

i get 6170 on a 26 x 12 Mejzlik on a JTEC muffler (DA-85)
6780 on a 26 x 10 Mejzlik
6750 on a 26A
6400 on a 26B
5750 on a 27A

if any of this can be useful to you,,,,,,

What oil are u guys using?

32 to 1 pens in all of my stuff from break in to never changing oil or the ratio

OK.

I pull the carb out this afternoon. Seems easy to do while the engine is mounted.

Found that one area of the gasket between the block and the mental plate is wet. A sign that there is leak there. However the two bolts holding the carb stack in place are tight. The locking compound'grip is present. It is weird.

Put it back with liquid gasket applied to all sides of the gaskets (3 of then).

Will try it tomorrow.

Also found the welch plug for WJ71 is 18-180.

Some additional question though. How often u guys maintain your da85? Going back to my record, I have burned 3 gallons gas in a month before the current maintenance. Seems short!

i have mie for 3 years and it only went to DA after it blew out the hub bearing around the 2nd gallon 3 years ago.

Tested the engine today. Fuel is pulled to the carb without any problem. A sign that the pulse is good at the carb.

However, the engine did not start. The plug is easily flooded. A couple of flips of the prop will do it. Without the plug installed, the gas drips badly from the engine. The gas is coming out from the back of the carb at the same time, more than expected. I noticed the same easiness to get the flooding before pulling the carb. So it should not be something to do with reinstall the carb.

Right now, my thinking is that the metering needle is not doing the job and opens more than needed.

sounds that way doesn't it?

Thanks.

Any other things could cause this?

Not really.

Metering needle/lever/spring assembly is pretty easy to get at. I'd take a look. No fuel should get past the needle unless the engine is drawing it in....only while it's running. The first thing I'd look for is debris in the needle tip or seat.

Checked the assembly and did not find debris. The needle looks fine.

I am in the process getting a new carb.