Tuning Problem
#1
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Tuning Problem
I have a real head scratcher. I have an Escapade with a DLE30. I flew it about 6 months and it flew well but, a problem developed I've not experienced before. I had not flown it for a week. I went to the field, fueled it up and started it up without problem. The engine was running somewhat rich at full throttle so I tweaked the HS needle about a schosche (my term for just a little) and took off. The engine, at full throttle did some popping like it was still rich but, I continued the flight. After a couple of minutes I turned inverted and after a couple of seconds the engine leaned out, then died, forcing a dead stick landing. Throught out the day I tried to richen the HS needle so the plane would fly inverted but in doing so the engine was extremely rich when upright. During the following week I examined the plane, replaced all fuel line tubing, being careful to make sure the clunk operated properly. The following weekend I experienced the same problem. As a side note, the low speed idle was perfect and transition to WOT was without problem. Any of you gas engine guru's have any idea of what is going on? Thanks for your thoughts.
Sonny
Sonny
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Thanks for the thought WRK. That was my next choice of action and I will rebuild the carb soon. Hopefully when I open the carb the problem will be apparent. I hope that fixes the problem but I still may not know the "real" problem. Things like that just bug the hell out of me. Just thought others may have had this same problem and were able to identify the problem. Thanks for your input. I'll get a kit and let you know the outcome.
Sonny
Sonny
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Thanks GIZ - I am gonna give that a try. It seems as though whatever the problem is that it would affect the running of the engine regardless of orientation of the engine (upright vs inverted). Also it just occured to me that I somewhat mislead things in my first post as the engine is actually mounted inverted on the plane so in reality it leans out when the ENGINE is upright (the plane being inverted). I will let you all know when I get the carb rebuilt and tested. Thanks
Sonny
Sonny
#6
FWIW, gas 2 stroke cycle engines don't care if they are upright, inverted, or mounted sideways, because of the pump type carbs. In fact the most common mounting IS inverted. Good luck with your carb rebuild, it is not hard, lots of help here.
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Thanks spaceworm - I rebuilt many a walboro so shouldn't be a problem. Like you say I have never known a 2 stroke engine to give a hoot how it is mounted, upright, inverted or whatever. My main concern is what actually is going on to cause the rich/lean problem as I have never seen that before. Usually if the engine runs bad one way it will run bad every way. I'll keep all advised of my findings. Thanks for your thoughts.
Sonny
Sonny
#8
One thing I have not seen addressed (although unless it was in the last 10 minutes I may not have remembered it), is about the vent hole in the regulator cover. In some cases turbulence will cause the ambient air to differ due to the plane's attitude, and affect the air the regulator "sees". Although I have not had the problem, I understand that some have soldered a tube over the hole in the cover and run some silicone tubing into the fuselage where there is no wonky air. Just a thought, I hope your issues go away soon.
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Actually, I have heard of the vent hole and the effect turbulence causes and considered that possibility. However, since the engine had performed normally in the past I discounted that as my problem. Perhaps I should again consider that possibility. I will rebuild the carb first and see if that helps. If not, your suggestion may be a viable solution. Thanks for bringing that back to mind.
Sonnytex
Sonnytex
#11
My Feedback: (7)
The solution to your new problem may be here.
Two words that match here, inverted and leaning.
Follow the link, it starts at post 1210, it will take you across three sites, hope this helps.
http://www.rcgroups.com/forums/showt...140905&page=81
Two words that match here, inverted and leaning.
Follow the link, it starts at post 1210, it will take you across three sites, hope this helps.
http://www.rcgroups.com/forums/showt...140905&page=81
Last edited by CARS II; 06-27-2016 at 05:52 PM.
#12
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Well CARS, those were very interesting reading. I am not considering one of the suggestions (vent hole mod) simply because I flew this plane for some time without the problem and no changes to air flow were made. My preliminary troubleshooting also eliminated the plug theory. Tuning is not normally one of my weaknesses but I have been out foxed by engines every now and then. The suggestion about the metering needle spring (affecting "popoff") sounds like something to investigate. Mr. gravity could do funny things to this function I think. I think my plan of attack is to first replace the diaphram then test. If no improvement, replace the needle spring then test. If no improvement do a full kit. If no improvement, break out the Bud Lite. Thanks for your input.
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Ok guys - Bad news. I went for "easy" and replaced the diaphram, metering needle & spring. I say easy because I did not have to remove the engine from the plane. That part of the carb was easy to get to. I started the engine at home and ran it. It started easy. I went to WOT and it screamed. I turned the plane over (wings were removed) and the engine continued to run without change of RPM. I was smiling big. Went to the flying field and took to the air. It ran rich upright and leaned when inverted. DAMN! No tweaking would correct the problem. Humm, does the fact no air flow other than the prop wash is showing its self? I guess my next ploy (after drinking my Bud Lite) will be a full kit job. Wish I had better news but then this is what keeps us going, isn't it. More after next test.
Sonny
Sonny
Last edited by sonnytex; 07-04-2016 at 03:06 PM.
#17
Start it upright with the wings on, then turn it inverted. That is more the actual flight configuration than running it inverted without the wings. Are there any fuel lines, including vent lines, that are in the area of the wing that could be pinched when inverted by the wing being on? Have you checked the whole fuel system, especially the clunk in the tank, for differences in it between upright and inverted? Is the tank securely fitted so it does not move around? Maybe try the regulator cover vent hole tube to inside the fuse? That is the one thing affected by airflow differences. Good luck.
Last edited by spaceworm; 07-04-2016 at 03:47 PM. Reason: added "especially the clunk in the tank"
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Well spaceworm I left the wings off during the test at home because turning a plane of that size with the wings still on was kinda difficult especially when the engine is WOT. As in my original post all tank/carb/vent/tubing was redone and tank mounting checked. Your suggestion of the regulator cover vent was thought about but I disregarded that since the plane flew very well the first six months without problem. Perhaps I will re think that possibility. I'll let you know what happens after my next attempt to correct this problem. I'll beat this sucker yet! I'll think on it whilst I kill this Bud Lite.
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CARs it does lead in that direction doesn't it? I just have a hard time with that since it flew so well before and nothing was changed. I'll be dwelling on that thought. Thanks
Sonnytex
Sonnytex
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Ok Guys, this has been an adventure for sure. Despite the fact the plane flew well for several months, I decided to go with the suggestion that erratic turbulence at the diaphragm equilazation port on the diaphragm cover was worth looking at. I soldered a short piece of brass tubing to the port. I then attached a 5" piece of silicon tubing to the brass tubing and routed the tubing inside the fuse via the firewall. Off to the flying field. Flip, Flip, Flip and she was humming. WOT!! A little rich, tweaked and settled to 8k nice and smooth. Take off and OMG, it worked!!!!!! It's fixed. YES!! Almost broke my arm patting myself on the back until.................. Second flight, popping, sputtering, coughing - inverted, leans and smooths, back up right, too rich again. Tweak, fly, tweak, fly back to old problem. My 20 years in the Navy taught me a few choice words and I used them all. Started to break down the plane to go home. When I took the canopy off, to my surprise, there was no sign of the silicon tubing from the carb. Inspecting the inside of the cowl revealed the tubing just flopping around. (Dirty words again). I again routed the tubing inside the fuse and this time held it in place with a zip tie. How it came out of the fuse is beyond me because it was plenty long enuf, but I digress. Reassemble the plane and start it up. A little rich, tweak and take off. OMG again, it flys just peachy keen. So there you have it. Thanks for all your suggestions.
Sonnytex
Sonnytex