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Basic engine tuning.

Discussion in 'Gas Engines' started by Terryscustom, May 6, 2015.

   
  1. Snoopy1

    Snoopy1 640cc Uber Pimp

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    Thanks for that have not seen this one seen a few that are similar. What I am trying to figure out is reading several sites and so called experts but came up with many pop pressure that is used in our aeroplane. There does not seem to be consensus.
     
  2. 49dimes

    49dimes Damn I'm hungry

    I simply would not worry about it. If you can tune your engine for good performance and have no fuel dripping then all is good. I checked my EME 60 when this pop off debate started. It was 10 psi. One of the best running engines I have.......Well......It was running lol.........
    20160605_175358.jpg
     
  3. 49dimes

    49dimes Damn I'm hungry

    FYI...........The metering plunger acts like a volume regulator not a pressure regulator.

    With that said...... Increase pop off decrease volume. Decrease pop off increase volume. As in volume of fuel.
     
    Snoopy1 likes this.
  4. Well it turns out there really was a problem with my DA 60. The mechanic said there was something like a calcium build up in the carb that was causing fuel flow problems. They were able to replicate the problem and get it running.

    Unfortunately in trying to resolve the midrange burble, it got too hot when I tried leaning out the low end. So I got to buy a new piston for it among a few other parts.

    I have to be honest. I'm somewhat debating selling it and get something a little smaller and doing epowah.

    The guy at DA said the best way to prevent this was to store with fuel in the tank and flip the prop every couple of weeks to get some fuel into the carb to keep it wet. This might be hard to do considering A) I'll have to have reminders to do it and B) I store the plane vertically on a wall to save space in my shop.
     
  5. I've been having nothing but problems with my DA 60 getting a proper a setting with it .today I had a flame out on my third flight while doing a hammerhead , I landed dead stick with no problems . I opened up the top end 1/32 richer which made it a lot easier to start but Now I can't get the idle to slow down with giving a quarter to one third of the throttle trim to close the carb and slow it down . These Waldro carbs are frustrating to get properly dialled in , I was using a fresh gas mixture which helped . I might just get one of those Walbro rebuild kits to resolve the problem if I can't maintain a easy start on Five flips and if the high end keeps acting up
     
  6. Jlc

    Jlc 70cc twin V2

    Sounds like you have the low end too lean. Deadstick, hard starting, and high idle.
     
    Rusty 73 likes this.
  7. Flyingjon

    Flyingjon 70cc twin V2

    I'd like some ideas on starting my da 70. I've been flying in 90° weather lately with 80%~ humidity. It'll start and run fine the first time of the day, but after I've landed, fueled, and waited for my turn again, it's a real pain to start. I have to come for 3-4 flips, choke off 3-4 flips and it runs for 1-2 seconds. Choke 3-4 flips, choke off for 3-4 flips and its going for 2-3 seconds. Repeat this process 6-8 times and your arm is tired, sweat is running into your eyes, and if your lucky the engine will start.

    Then, once it is running it'll struggle to pickup speed. I have to sit there and goose it several times to get it to rev up.

    Earlier in the spring and winter it ran just fine...

    FYI @ericrs has an eme70 that is acting about the same now that it's hot out.
     
  8. Snoopy1

    Snoopy1 640cc Uber Pimp

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    Just for interest at the beginning of last years flying season a friend of mine bought a new DLe 35 ra. This engine has been a painful until yesterday.
    From day one the engine started every time real good. But it always did some hunting from 1/4 throttle and up. You could fly it but not well. After endless tuning, tank change and many other things. Still no solution. Bought a new carburetor and still no change. Note we did remove the ignition and checked it out with all the rexcell testers all ok. Still no success. While at the field yesterday we decided to change the ignition with one spare unit I had on hand problem solved cannot belive it was ignition all the symptoms pointed to a carburetor problem. Note that is why I was asking adout pop off pressure. Boy can these little engine try your patience and knowledge.
     
  9. @Flyingjon it sounds like you may be running into a vapor lock scenario. How soon after landing are you trying to fire the engine up again? Check the fuel line location and see if there is a way to move it further away from the exhaust. Also, check to see if there is a way you can get some more air flowing through the cowl or just open it up a bit more so it will cool better when sitting between flights.

    Just my thoughts based on the symptoms you provided :)
     
    Flyingjon and Alky6 like this.
  10. Jetpainter

    Jetpainter 640cc Uber Pimp

    One of my DA50's does that. If you try to just land, fuel up, and fly again it's a total pain to restart. If you let it cool for say 15 minutes, it will start on the first flip almost every time. If you wait more than an hour you have to choke it again.
     
    thurmma and Alky6 like this.
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