DA-85 Needle Tuning
10-04-2007, 09:12 PM
#1
DA-85 Needle Tuning
Hello,
Just back from flying my new DA-85 in the AW 75cc Extra 260. Flew 3 times at about 10 minutes each. Lawnboy 32/1 with JTec pitts muffler. The engine power on this plane was out of sight. Idled very well with no deadsticks.
Having owned a DA-50 for 2 years, it seemed the low to midrange burble on the 85cc is very pronounced and noticable. I leaned the low needle 1/4 turn after the first flight and this did not reduce the burble. About the only time the burble or popping goes away is when you pull a vertical.
I suspect the engine is probabally set too rich as usually the case from the factory. I'm at about 600 ft. altitude. Before I jump on the needles, I'm interested to hear from others with the DA-85 how much you turning in the needles and what were the results in smoothing out the engine?
One more question. Should I use the muffler gasket or no gasket?
Thanks - Jaketab
Just back from flying my new DA-85 in the AW 75cc Extra 260. Flew 3 times at about 10 minutes each. Lawnboy 32/1 with JTec pitts muffler. The engine power on this plane was out of sight. Idled very well with no deadsticks.
Having owned a DA-50 for 2 years, it seemed the low to midrange burble on the 85cc is very pronounced and noticable. I leaned the low needle 1/4 turn after the first flight and this did not reduce the burble. About the only time the burble or popping goes away is when you pull a vertical.
I suspect the engine is probabally set too rich as usually the case from the factory. I'm at about 600 ft. altitude. Before I jump on the needles, I'm interested to hear from others with the DA-85 how much you turning in the needles and what were the results in smoothing out the engine?
One more question. Should I use the muffler gasket or no gasket?
Thanks - Jaketab
10-04-2007, 09:21 PM
#2
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RE: DA-85 Needle Tuning
i have not had to touch the low end but maybe once. I am on my 2nd gallon and i have had to keep going lean on the high end about every 2 flights. The high is set pretty rich along with as the rings seat u need to keep leaning the motor out to hit peak. I am with you on the power of this motor. I am thinking 85cc is what i need no 50cc or 100 cc birds lol
I am running a 26A vess getting 6810 hot after landing i think i use to get 6400 or so cold on this prop on the 1st tank, I am also on a JTEC muffler the cheaper one....
I am using a muffler gasket my exhaust looks like your pic. you will see this until she broken in well.....
I am running a 26A vess getting 6810 hot after landing i think i use to get 6400 or so cold on this prop on the 1st tank, I am also on a JTEC muffler the cheaper one....I am using a muffler gasket my exhaust looks like your pic. you will see this until she broken in well.....
10-04-2007, 09:43 PM
#3
RE: DA-85 Needle Tuning
Krayzc,
Something I should also mention, the carb is spitting small amouts of fuel back into the fuse. Is your's doing this also?
If it keeps this up, the inside of the fuse will be a mess.
On my first 9 minute flight, the engine drank 1/2 of the 33 oz fuel tank.
Second and third flights it drank about the same for 10 minute flights.
Just before flying the first time, the tach reading was 6430 with the Vess 26A.
Jaketab
Something I should also mention, the carb is spitting small amouts of fuel back into the fuse. Is your's doing this also?
If it keeps this up, the inside of the fuse will be a mess.
On my first 9 minute flight, the engine drank 1/2 of the 33 oz fuel tank.
Second and third flights it drank about the same for 10 minute flights.
Just before flying the first time, the tach reading was 6430 with the Vess 26A.
Jaketab
10-04-2007, 10:27 PM
#4
RE: DA-85 Needle Tuning
ORIGINAL: Jaketab
Krayzc,
Something I should also mention, the carb is spitting small amouts of fuel back into the fuse. Is your's doing this also?
If it keeps this up, the inside of the fuse will be a mess.
On my first 9 minute flight, the engine drank 1/2 of the 33 oz fuel tank.
Second and third flights it drank about the same for 10 minute flights.
Just before flying the first time, the tach reading was 6430 with the Vess 26A.
Jaketab
Krayzc,
Something I should also mention, the carb is spitting small amouts of fuel back into the fuse. Is your's doing this also?
If it keeps this up, the inside of the fuse will be a mess.
On my first 9 minute flight, the engine drank 1/2 of the 33 oz fuel tank.
Second and third flights it drank about the same for 10 minute flights.
Just before flying the first time, the tach reading was 6430 with the Vess 26A.
Jaketab
10-04-2007, 10:37 PM
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RE: DA-85 Needle Tuning
just what JoeAirPort says my low is not spitting it like that. The gas mileage is also good. i have a 32 oz but after i get it broken it i am looking to see if i can go smaller, its not a pressing concern of mine just wondering most likely i will never do it lol......the 2nd gallon i think you notice a big jump even though at breaking in the power is nice.....
10-07-2007, 06:19 AM
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RE: DA-85 Needle Tuning
Hi,
My low-end needle was set very rich from the factory. I had to turn mine in about 3/4 turn to get rid of the burbling. Runs amazingly well now.
Steve
My low-end needle was set very rich from the factory. I had to turn mine in about 3/4 turn to get rid of the burbling. Runs amazingly well now.
Steve
10-07-2007, 07:49 PM
#8
RE: DA-85 Needle Tuning
Gentlemen,
Discovered a problem with the JTEC. If you look at my pic in post #1, you see oil running down from the bolt hole. At first, I thought I might not have used enough gasket sealer or torqued the bolts enough. I removed the muffler, and used a generous amount of Permatex Ultra Copper and reassembled without gasket.
Same result - only oil is leaking out of both bolt holes now. Upon inspectiing the muffler this evening I discovered it is defective from an improper or incomplete weld on the flange. The flange plate on the port side is welded to the muffler. The oil and gas is working it's way between the flange and the muffler and exiting out the bolt tubes. No amount of gasket or sealer will stop the leak. I was able to confirm this by placing a silicone tube into the bolt hole from the port side. I put my finger over the bolt hole tube to seal it from the outside and blew into the tube. You could easily see air mixed with bubbles exiting between the welded flange and the muffler.
It's made a big oil mess on the inside of the cowl.
There are 2 of us at my field with the DA-85's and JTEC Pitts. Both are leaking from the bolt hole tubes. Plan is to contact the manufacturer tomorrow.
Finished my first gallon and tach reading is now 6780 before flying. Still have some tweeking to do with the needles. Still running too rich and burbling.
Jaketab
Discovered a problem with the JTEC. If you look at my pic in post #1, you see oil running down from the bolt hole. At first, I thought I might not have used enough gasket sealer or torqued the bolts enough. I removed the muffler, and used a generous amount of Permatex Ultra Copper and reassembled without gasket.
Same result - only oil is leaking out of both bolt holes now. Upon inspectiing the muffler this evening I discovered it is defective from an improper or incomplete weld on the flange. The flange plate on the port side is welded to the muffler. The oil and gas is working it's way between the flange and the muffler and exiting out the bolt tubes. No amount of gasket or sealer will stop the leak. I was able to confirm this by placing a silicone tube into the bolt hole from the port side. I put my finger over the bolt hole tube to seal it from the outside and blew into the tube. You could easily see air mixed with bubbles exiting between the welded flange and the muffler.
It's made a big oil mess on the inside of the cowl.
There are 2 of us at my field with the DA-85's and JTEC Pitts. Both are leaking from the bolt hole tubes. Plan is to contact the manufacturer tomorrow.
Finished my first gallon and tach reading is now 6780 before flying. Still have some tweeking to do with the needles. Still running too rich and burbling.
Jaketab
10-07-2007, 11:10 PM
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RE: DA-85 Needle Tuning
i have the JTEC muffler also i figured once the motor is broken in it will stop this (guessing) 
I am on my 3rd gallon now (today) with RPM of 6900 after landing with spikes of 7K sounds like i will be able to move up to a 27A or so prop. I am not expecting much more or any more RPM increases but who knows
I am on my 3rd gallon now (today) with RPM of 6900 after landing with spikes of 7K sounds like i will be able to move up to a 27A or so prop. I am not expecting much more or any more RPM increases but who knows
10-08-2007, 12:53 AM
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RE: DA-85 Needle Tuning
As far as the muffler;
I have a DA 50 with the same set up.
The guy that owned the engine before me tightemed the bolts to the point that both sides of the muffler were distorted.
In other words, by tightening the bolts, the flat surface that contacts the head, and the flat surface where the bolts are
got bent.
This led to bigtime leaks and black goo everywhere. It also broke the welds on both sides where
the front bolt was. I had to use aluminum weld fix the breaks, and built up the dips where the bends were
with aluminum weld.
To spread the load on the bolt thing, I got a piece of metal and drilled holes in it to act as a big washer on the
outboard side of the muffler, and also supported the muffler to the engine mount with a metal strap.
Hope that helps...
I have a DA 50 with the same set up.
The guy that owned the engine before me tightemed the bolts to the point that both sides of the muffler were distorted.
In other words, by tightening the bolts, the flat surface that contacts the head, and the flat surface where the bolts are
got bent.
This led to bigtime leaks and black goo everywhere. It also broke the welds on both sides where
the front bolt was. I had to use aluminum weld fix the breaks, and built up the dips where the bends were
with aluminum weld.
To spread the load on the bolt thing, I got a piece of metal and drilled holes in it to act as a big washer on the
outboard side of the muffler, and also supported the muffler to the engine mount with a metal strap.
Hope that helps...
10-14-2007, 11:08 PM
#12
RE: DA-85 Needle Tuning
Not overtite, but a defective weld, design, or muffler. It made a nasty mess on the inside of cowl. JTec is repairing the muffle, but I'm grounded until they return it to me. Looks like I'm out 8 bucks on shipping too.
Here is the email explanation from JTec.
"I see the leaks. Its not a defective weld, it could be in the tube area's. It would be in the mounting tube. The bolt hole tubes are welded in place and ground out (cleaned up ) then the flange is welded on. The tubes are in the main structure and do not directly attach to the flange. The inside of the flange can not be welded. Yes there may be some seepage from the inside flange to the bolt tube. The other posibility would be the we might have broken through the tube when grinding.
It looks like maybe if we sealed the inside flange that probably would stop the leak if that is where it is. Possible with a gasket sealer or a JB weld type material.
Send them back and please let us see them so we know what we have to do to either repair or replace the mufflers."
You be the judge.
Jaketab
Here is the email explanation from JTec.
"I see the leaks. Its not a defective weld, it could be in the tube area's. It would be in the mounting tube. The bolt hole tubes are welded in place and ground out (cleaned up ) then the flange is welded on. The tubes are in the main structure and do not directly attach to the flange. The inside of the flange can not be welded. Yes there may be some seepage from the inside flange to the bolt tube. The other posibility would be the we might have broken through the tube when grinding.
It looks like maybe if we sealed the inside flange that probably would stop the leak if that is where it is. Possible with a gasket sealer or a JB weld type material.
Send them back and please let us see them so we know what we have to do to either repair or replace the mufflers."
You be the judge.
Jaketab
10-15-2007, 03:07 PM
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RE: DA-85 Needle Tuning
i just had my muffler off this past week to add in thrust on the motor and I recall mine inside weld looks like yours bummer i am steady flying right now JTEC is located about 20 min from me. mine does it out of the rear hole a little but the front hole has stopped. well run more gallons on her to see what is the deal.
tks for the udpate
tks for the udpate
