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Old 05-27-2013, 05:54 PM
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Quote:
Originally Posted by pcastine View Post
When approaching for landing, the engine remains at a high idle, then slowly returns to the normal idle setting. I can never remember: is this an indication that the engine is too lean on bottom end, or too rich?
Thanks,
Pete
Too Lean and warm
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Old 05-27-2013, 08:44 PM
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Gettin' Lower!
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Quote:
Originally Posted by Prof10000 View Post
Great points. I was going to install the Tower / Great Planes microswitch based kill switch to ground the motor like the kill switch mounted to the airframe butIdon't like the reliability of a microswitch. So, I think I will simply install a slide switch activated by an added servo that will ground the motor.

This Walbro carb has a pretty stout spring on the throttle and if the servo linkage pops off the throttle should close completely since I backed out the mechanical idle stop so it is out of the picture. Only the throttle servo controls the throttle movement.
just a thought: I think gasser guys remove the spring most of the time. It will suck the juice out of the rx batts and make the throttle servo work a lot harder. I usually remove the spring also.
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Old 05-27-2013, 09:04 PM
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Use a good quality servo on your throttle and you won't notice that spring on throttle. Another reason to leave it in there besides closing if linkage pops off is if you take it off over time it will wollar out your butterfly shaft on carb from vibration.
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Old 05-28-2013, 10:42 AM
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Plug color?

Delete
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Old 05-29-2013, 06:27 AM
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Quote:
Originally Posted by bradp View Post
just a thought: I think gasser guys remove the spring most of the time. It will suck the juice out of the rx batts and make the throttle servo work a lot harder. I usually remove the spring also.
Not so. The throttle servo works only very slightly harder. The extra servo load is not worth the spring removal action, which often is cause for carb throttle plate damage.
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Old 05-30-2013, 02:44 AM
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Pe,

How can the throttle plate become damaged by removing the spring? I have a 12 year-old DA 150 which had the throttle spring removed; the original throttle plate still works fine. Is this a damage caused by improper removal?

Thanks,
Pete
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Old 05-30-2013, 02:38 PM
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Quote:
Originally Posted by pcastine View Post
Pe,

How can the throttle plate become damaged by removing the spring? I have a 12 year-old DA 150 which had the throttle spring removed; the original throttle plate still works fine. Is this a damage caused by improper removal?

Thanks,
Pete
I'm not Pe, but I can answer this! The throttle spring doubles as a spacer; you remove it, the throttle blade will cut into the carb throat. Its steel, carb body is aluminum. Look down the carb throat of that DA150, I bet you'll see some groves cut on the side opposite from where the spring was. If not, maybe the throttle linkage geometry was somehow holding it off.
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Old 05-31-2013, 06:28 AM
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Carb body is ZAMAK, throttle plate is brass. The plate vibrating inside the carb bore will damage the throttle shaft bore AND the throttle plate.
Shaft bore damage will cause throttle binding. (like sticking wide open?)
Throttle plate damage will upset your mixture.

Like Low cal said, you must have had a force holding the plate to one side of the bore or all shaft play removed, which is what the spring normally does.
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Old 06-01-2013, 01:43 AM
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Why remove the spring. I just cut the end of the spring which pulls the throttle plate to idle position, the rest of the spring stays in place and does its job as a spacer.
Works well for me on many models.
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Old 06-05-2013, 03:26 PM
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The throttle spring on a DA150 is pretty stiff. I hooked up a nice Savox digital, brushless servo to my DA150 (over 100 oz/in), and after 20 mins the servo was hot enough to hurt my hand (I'm a wobbie, though!) Rather than unhooking the spring, I just relocated the hook, cutting the tension approximately in half. Now the servo doesn't get hot, and if I unplug it, the spring will close the throttle, turning the servo at the same time. Perfect!
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Old 06-05-2013, 09:07 PM
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Removing the spring is not an option until I get a failsafe remote kill switch to pull the throttle closed. I also have some ridiculously high torque servos in the plane. Battery is a A123 pack which is in excellent condition and monitored closely.
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Old 06-05-2013, 09:20 PM
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Update on finding a replacement phenolic insulator for my discontinued Fuji Imvac BT 34B. I am very lucky to fly with Andy Low who owns Electrodynamics (wiring, special switches, regulators, etc.) He has done development work for Fuji Imvac and he contacted the President of Fuji Imvac and they sent the last and only insulator for the motor. My cost is $22 including shipping. Fuji said the motor is discontinued and there are no more spares being made.

Bill
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Last edited by Prof10000; 06-05-2013 at 09:53 PM.
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Old 10-21-2013, 06:43 AM
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An opinion/advice needed

Can you please tell me your opinion about these spark plugs. Also why is the plug (the one in the right in the photo) from left cylinder whiter then the other. After this test I switched the plugs and run on the ground about 5 min at idle but also one full rpm 5 sec. and the one that was whiter became darker(in the last 2 photos where I hold my finger distant). I've compared them with pictures from threads on this forum but still need opinions please. Engine is 53 cc twin, 95 octane gas, 1:25 mix with mineral Bell Ray oil. This was the second tank trough it. Prop Vess 21A with less load than B series. Full rpm - 7200, idle about 2100. It does'n die or hesitate when accelerated rapidly. The tune I've made started from 1,5 turns on both needles, I needed to open the H until almost 2 turns to reach 7200 rpm, at 1,5 turns it had only 6800 rpm. Is this normal? I know we need to lean them right? It was a bit cold outside to tell you the truth, about 45 F or 7C. Is it possible the engine got too hot? It was cowl off, but didn't want to warm it after every screw adjust. so I adjust and restart several times, each time with a 1-2 min idle and 5 sec full rpm. So I got 7200 at almost 2 turns out H, then moved to L at 2500 rpm and leaned it until I obtained 3600rpm, after that it started to die and open the L 1/4 or slightly more. When I easy advance from idle it sounds rich and 4 stroking. Thank you for your patience of reading this, I'm grateful for any opinion and advice.
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Old 10-22-2013, 12:31 AM
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I thought I knew gas engines, but I guess this one has me beat... Hope for some advise

I have a DLE-50 which has been running really well. Not heavily used, but when I bring it out, it was always super reliable. Then one day this summer, I noticed that when my plane was going vertical, it would miss ( almost like its reaching ). This started very slightly and then within 3 flights, it got really bad and quit in the air. Once I got it down on the ground, it did not start really well.

First I though it was the carb being lean.. Tried a number of things including replacing the insides of carb, and finally I bought a new carb ( and reed value ). Nothing. Then I changed the ignition module and spark plug. Nothing. Then I changed all the fuel pipes and replaced tank...

Finally I decided to open up the case and clean and re-seal with the correct gasket sealer.. Alas to no avail... Before I just go out a buy a new engine I thought I would ask this community.. Someone might have a great idea.

One thing that is really odd, it that if the engine is at complete idle and I gun it, I get the "Im lean bark sound" from the carb and if I did not go back to idle, it will stall. If the engine if at semi-idle ( say 2000 rpm ) I can gun it and there is no issue. I have opened the LE and HE needles, but can not seem to get rid of this issue. The engine has good compression and I can not see any obvious issues with the engine...

Any clues?
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Old 10-22-2013, 02:19 AM
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Approaching critical AoA...
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sacalu, in my opinion the plug on the right is just about the perfect color for a well-tuned engine. The Left plug shows the engine is a bit rich. It's strange to see such a difference in the plugs; typically they are close to the same color. My only guess would be to check the reed cage to see if there's any cracks or chips in the reeds or something just inside that could be causing one cylinder to run leaner than the other. Also - I suppose you have good baffling from the cowl against the cylinders?

Pete
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