FBaity

My Feedback: (2)

I have a DA-50 in a SBACH 342 and have about 50 + flights on it in past year. Yesterday the engine would try to quit at the bottom of reverse outside loops. I could turn upright at it would run fine. All fuel lines including the clunk line are tygon and I just got back from the hobby shop with new line to install. On inspecting the installed lines outside the tank none seem hard and they have been in there little less than a year.

I just wonder if others have experienced a problem like this and the solution was something other than the tygon.

Thanks

irocbsa

My Feedback: (12)

Hooray for Ethanol! As long as you continue to use fuel with Ethanol in it, plan on replacing the lines about once a year. I recently switched to AvGas because I got sick of digging out my tanks every year and replacing all the lines. If you want/need to continue using unleaded pump fuel, I think McMaster Carr sells some fuel line that is more resistant to the effects of Ethanol. I'm sure someone will chime in here and shoot you a link.

krayzc-RCU

My Feedback: (31)

rich en up the low end about one screw driver blade....

FBaity

My Feedback: (2)

I run ethanol free fuel. Roger on richen low end. Took tank apart and clunk line doesn't appear stiff. Will replace it of course..........was afraid there wouldn't be any obvious solution. I did richen L and H needles at the field yesterday but didn't seem to help much.

Thanks

spaceworm

Similar recent post, CO was due to short in ignition circuit. Engine should not cut out due strictly to inverted position. If fuel pickup is ok, then look to electrical possibilities.

BarracudaHockey

My Feedback: (11)

Frank, ditch the tygon in the tanks and replace it with Viton

Several vendors sell it, I get it from Red Aero RC, that paired with a ceramic clunk is a bullet proof fuel tank installation.

MTK

Frank,
When engines go lean when inverted, it often means a lean low end...

I was as aggravated as most with gas lines several years ago.... so I researched and found the best value for my buck. I now sell the best gas line there is and it's less expensive than the yellow tygon. Is very flexible and stays flexible for years. Contact me directly please at my email address

3dsky

My Feedback: (84)

If you got 50 flights and it ran great…. I would service the carb and check the reed valves for damage. Get a carb kit and new reeds, nice to have on hand (if reeds are ok you can reverse them if not sitting flat). Sometimes the card mounting screws loosen up causing air leaks.
Clean the card screen, remove the needles and clean every port. Most of the time a new diaphragm will fix this, but it does not hurt to just service the carb. Ethanol based fuel will harden the rubber just enough to cause a problem.
But….it just may be to lean….
Any update on what you found??

kmtranmd

My Feedback: (71)

I have the exact same problem with one of my DA 50 motors. Don't see how that's ignition module problem when it runs fine upright.
Went through the same mental exercise of adjusting needle, changing clunk lines, rebuilt the carb, even sent it back to DA for troubleshooting. I have about 20 gassers from 30-170cc size so I know a little bit about gasoline engines.
Still got same problem in my Aeroworks Pitts Python that flew fine for about dozen flights on it before.
Got frustrated and pulled the motor and replaced with DLE 55.
Motor still sitting on the shelf.
Any expert out there want to buy a DA 50 for great price???

3dsky

My Feedback: (84)

My DA 50 ran great on pump gas from the start (had the air box to diaphragm trick) and never had a problem going to very low idle inverted flat spins and never had a dead stick until after 4 years, never serviced it. Had the dead stick, rebuilt the carb, reeds and went back up it was fine after that.
PM me on your DA 50
Gas is a big variable IMO, % ethanol can vary and other additives to cause a lean or rich runs. Maybe the diaphragm just gets hard enough to cause it to run lean by not pumping fuel.
I have switched to Shell Racing Fuel URT 105 and just like OIL there can be big difference.
ON 2 of my motors I used this fuel for 1 season and just started the engines and found that all of the Tygon tubing was still soft and the diaphragms look to be soft. Engines run great. At @ $17 per gallon this may not be the best solution for fussy engine runs but so far I love the URT 105. Using a 40 to 1 oil mix. Down side to using URT 105 is getting it when you travel, smell, and very high cost.
Since I service my engines every year, new rubber the pump gas works for me. It is fun just playing around with new stuff to see what happens.

kmtranmd

My Feedback: (71)

I run Chevron ethanol free gas and Redline racing oil 50:1 on all my gassers.
I'm doubtful it's gas or oil as source of the problem, since my other 20 or so gassers all run fine, except for this one DA 50 problem.
I rebuilt the carb and had DA check it out and could not solve the problem.
I'm guessing there is a small piece of dirt running loose in the carb that gets in the way when motor is inverted.
I might run it through the ultrasonic cleaner again to see if that solves it.

3dsky

My Feedback: (84)

I agree the gas would be the last place I look. I have been going back to adding the low throttle stop screw to keep the servo from bouncing the arm to far closed. This gives me a solid stop idle. I can move the stick up and down without the arm over traveling. Since I never use the low throttle trim to shut the engine down anymore with on board kill this seems to help. I have also seen digital servos move around when idling or at 1/2 , I think it is the servo trying to hold setting when pushrod is vibrating.
We tested a DA 50 on the ground flipping it inverted and we were able to get the engine to die after holding it inverted. I do not remember all the things I did but I remember adjusting the engine inverted, using a stop screw, and an air box on the carb diaphragm. Got it to work on 87 car gas.
My experience using ethanol free gas has been…….. I think I have better range on the carb needles making it easier to adjust the low end and transition. The Shell URT 105 works better than AV LL Gas and others I have tried. Works great in the smaller gassers, solid midrange. The station I use stopped selling ethanol free gas so I am looking for another source. I have a source for the Shell but the cost is nuts.
It’s frustrating to have a high end engine not outperform the China copies. Good luck.