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Old 11-19-2008, 11:29 AM   #40 (permalink)
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Posts: 662

Join Date: Jun 2008

Well, even after confirming with Finless about servo direction, it turned out that mine was reversed for 1 good reason. I did the blow dryer test incorrectly. Although it did richen the needle when it became hot, it did so even before reaching the target temp and I just assumed it was working correctly. Let me explain this and I hope it helps someone else new to this.

The proper way to test would be to temporarily set target temp at the MGP minimum of 70C. That way you don't have to wait too long before the mixture servo does something. Ok apply heat with blow dryer and at 43C, the mixture control will be activated and will center the servo. A little over 43C the servo will start to lean out the needle to reach the target temp. When the temperature reaches 70C, the servo should start richening the needle. This is the correct process to make sure the servo is going in the right direction.

When I did my first tests, the servo richened the needle and I said to myself, wow cool. But it did so without even reaching the target temp which is wrong. This was the reason why when I tried it last weekend, I couldn't make it to work because it was doing the reverse. Yesterday it flew great. I set my maximum lean position to 1 full turn (my normal setting after break-in) and maximum rich position at around 1 and 15 clicks or so. Center is about 1 and 5 clicks. I want the engine to have enough lubrication during warm up. Observing the servo on the ground, as soon as engine is hot enough to activate mixture control, it centers the servo and then after a few seconds goes to my leanest position. I did some temp inducing maneuvers and quickly brought the heli to a hover were I can see the mixture servo and sure enough it was at the rich position, for awhile though, because it started to lean out while I was hovering.

BTW, I am using CP15%.

I hope this helps other nitro newbies.
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