w8ye

My Feedback: (16)

The idle speed screw is removed and not replaced

P51p

Ahh......yup I already did that.

kmeyers

P51p

What is the throttle linkage begining to end. You said 3004 servo:
What horn lengths? servo center to hole used, throttle shaft to hole used. Angles (do you use the rule of right angles)?
What type and length of pushrod? Supported? Ball links? Clevises? bends?

Dealing with others in the past most problems end up falling into two types, setup and tuneing.

I am not saying that there is not a problem with your engine. I'm just saying that is not where I start looking first.

To start with the 3004 is a ball bearing, nylon gears, standard servo. Certainly up to the task of throttle control if setup right (we don't like fast servos on gas thottles in general at our field).

kmeyers

All the gassers I have bought came with this screw in place. For the servo to control the idle position the screw needs to be removed.
This is a fair first question. Many do not remove it and wonder why they cann't kill the engine with the throttle or set the idle lower.
Your level of experience is completely unknown to me.

P51p

kmeyers......Fair questions indeed.

I have been flying giant scale gas for about 3-4years, and this is my third gas plane. The other two are 40cc and still fly them and they fly great and idle well. However ths is my first DLE engine, the other two engines are CRRC Pro 40cc and work really good, never had any idle issues with them but they are side mounted carburetors and my reasearch the last few days seems to indicate that the rear mounted carburetors may be a little more sensitive to outside temperatures and needle adjustments.....not sure how true that statment is though, still learning.

I think the throttle linkage is good...pretty much the same setup on my other planes. I did notice the idle around 1900-2000rpm when I first had the engine on a test stand but figured I would deal with it when the plane was done and ready.

I did disassemble the carburetor the last few days and cleaned all the holes and did notice one of the progression holes that is responsible for idle seem a little clogged perhaps with a metal burr maybe during the milling process. It's all put back together now and ready to run it tomorrow if the weather permits.

P51p

BTW.....Removing the idle screw was the first thing I did when I was setting up the plane. I also use a fiber optice kill switch from smart fly on all my gas planes, I never liked depending on closing the carburetor all the way to kill the engine.

P51p

I actually misunderstood the question" w8ye" was asking about the idle screw, I thought he meant the actual low end needle screw and not the idle stop screw thats why I was curious about replacing it and where to buy one.

P51p

Just curious.....why don't you guys like fast servos on gas throttles at your field? What would you suggest as a good servo for my 50cc?

captinjohn

A fast servo is not needed. Snapping the throttle from idle to wide open is not a thing you want to do with some engines. If you can set-up the travel from idle so transition towards full throttle matches what stick movement and actual RPM takes place...the result will be much better. Its time for you to read all about throttle curves and the length of the servo arms and throttle arms. So check back....its all there. Capt,n

w8ye

My Feedback: (16)

it is better if your throttle lever is not moved fast

blikseme300

My Feedback: (118)

Your problem is puzzling. A clue, I think, is that you say it has been doing this from the start. There was some posts a while ago about the reeds of an DLE opening up and leaking when the carburetor and reed block assembly was screwed down. I will search for this and post the link if I find it.

Bliksem

captinjohn

A good Idle speedof about 1600 + or- some is average. Adjust the Idle speedso it is at asmooth RPM and not so fast it pulls your airplane on the taxi way. Thats all is needed!................................

Uncas

My Feedback: (1)

Just remove it. You do not need it.

K-Bob

My Feedback: (1)

Well, it is a thing I do with my engines and I would expect no less than immediate response. If that wasn't happpening I would tune it correctly or get a different engine.

captinjohn

The key word here is "some"....not all................

w8ye

My Feedback: (16)

There's someone jumping in to bark to just hear the roar?

The Futaba 3004 std bb analog servo on 6v goes from limit to limit in .19 sec

The Hitec 5625 digital servo does the same feat at .14 sec.

That's a whopping .05 seconds difference in throttle speed.

I doubt any of you would be able to accurately measure that with a stop watch?

P51p

Update......

I started the engine today after reassembling the carburetor and it started right up with no problems and for the first time I was able to get the idle down as low as 1500-1600 rpm with out the engine dying. Before I took the carburetor apart the lowest it would go would be about 1900-2000rpm, so I think there was definitely crap in one of the progression holes that is responsible for low idle. Tomorrow I will try to work on tuning it a little, had no time today to do it.
I did look around the the carburetor gaskets for air leaks, did not find any. May be difficult to find if it's a subtle air leak though.



Still curious about the recommended throttle servo.....digital or analog? Metal or nylon gear? Any thoughts?

w8ye

My Feedback: (16)

I have been using the 3004 on the throttles without any trouble.

I've used a bristle out of a wire brush to run into those idle holes in the carbs.

P51p

Yep....I stuck a small wire into the holes and moved it around, seem to do the trick.

Scota4570

If you suspect an air leak you can easily diagnose it. Spray some carb cleaner around the suspect places with the engine running. The liquid will be sucked in and cause the engine to run differently when you hit the right spot. It does not need to be carb cleaner. Anything flamable will work. I just use it because it is handy and evaporates clean. I suppose butane might work if you put a hose on the container to direct it.