DA50 acting funny when cold.

[RustyTumbles]

I've been flying my WH extra with a DA50 of almost six months now and over the last few weeks it has been acting up when the motor is cold.

When I start it up I have to let it idle for a 1min or so before I can move the throttle up. If I don't wait it stops, like the low end is too leean. But once the motor is warm and you get it throttle open and run it up it runs perfect. I have richend the low needle about 1/4 turn over the last two weeks and it continues to do it. I've checked all my filters, the carb block for leaking gaskets, etc, run fresh batch of fuel and it still remains. I have used a temp gun after a full flight of IMAC style flying and the jug is around the 73 dregree C mark and the plug area 75 degrees C and the crank case 65 degrees. The motor is baffled and not getting hot in flight so I can't see that it is a lean setting causing the proplem. Has anyone else experienced this type of thing? and if so what fixed the problem?

[notorious_benny]

Did it do it again today Rusty?? The low needle isnt moving from vibration is it? Though I would expect it to vibrate out (richer), not in.

I know the DA's are a different beast, but the manual for my 3W says that the motor may not transition until warm if you have the low needle at the optimum setting, I have noticed this, in that it may bog a little till warm but not stop completely and if I richen the bottom even a little it transitions much easier when cold.
But I think you are saying that even if you richen the needle it wont transition right??

Could it be a fuel draw/pump problem? Is the diaphragm intact and correctly hooked to the little metering arm? And is that little arm at the right height?? (Ie you didnt bend it towards the carb body somehow)

Have you tried pinching your other carb and bolting it on to the motor, that way you can narrow the problem down, if it goes away there must have been something in the carb if it persists then there is something else going on.

Lastly....... actually make that firstly! (lol), what does Howie reckon?? I am sure the guru will figure it out for you.

[notorious_benny]

Rusty I jut re-read your post a little more carefully, it dosnt sound like you have cleaned out the screens in the carb. Maybe its just a bit of s&^t in there causing it to run weird.

[RustyTumbles]

Yeah it was doing it today. I have checked the screens as well and there are clean. I can't swap carbs as the other motor has been sold and is now in Townsville. I have put locktite on the needles and I'm pretty sure they are not moving. I have also checked the plug and it looks like the needle settings are good. (Dark around the outside of the plug and a browny colour in the middle) I haven't spoken to howie about it yet.

[JoeAirPort]

This is usually a sign that the low needle is leaned to the correct setting. It should not transition until it warms up a bit. Especially in unusually cold temperatures (winter-spring). If it transitions right after starting then it's usually too rich. The only thing is that you say it just started happening...and that you have already richened the low needle. I'd check that you have a good plug and it is gapped right. Not sure what else to say about it. If it runs perectly when it's warm then it's not such a big problem IMO. I'd get bored of waiting a minute for it to warm up though. Should be only 10-15 seconds. 30 max.

[Tired Old Man]

Sounds like it's working exactly like it's supposed to. If it didn't do it this way before it was wrong before. It's possible the low needle is off a little, but since you did not note if the engine stumbled or drowned when the throttle was advanced the status is unknown. You mentioned in one post that the engine would "bog" when cold. Your move to richen the low needle was a good one.

The temps you noted are interesting. Below 50c and you can expect the engine to stop at any time for no apparent reason. The temps you note are close enough to that to be an issue with mixture settings and engine relibility all by themselves.

Let it warm up a minute or two at mid throttle before flying. It's much better for the engine to do so.