BusterBust

My Feedback: (3)

GDay


I have a new DLA 56 that i put on my Slick 540, i have put about 3 tanks of gas through it on the ground fiddled with high an low end to get it to a reasonable state (understanding that it will still take a bit to break in). The issue i am having at this point is when i throttle up and then pull it back down to idle the engine rpm will drop a bit ...but will hold at an rpm way higher than idle and after about 8 to 12 seconds will then drop down to the idle speed, this happens weather i pull the stick fast or gradually to idle. If i start from idle, and the throttle reaches about a quarter up it goes into the higher rpm thing again (higher rpm than it should be at that throttle setting). i have had a couple of quick flights with it now, good response, good high end, need to tweak the lower end still as it four strokes .

Is this higher rpm to 8-12 seconds when i have the stick at idle, still a tweaking issue (breaking in thing?) or is there something im missing?

Thanks in advance

MetallicaJunkie

lean low end?

Lnewqban

Could your fuel tank be developing some pressure?

If so, you could have an over-rich mix for those few seconds.

Tired Old Man

My Feedback: (1)

The low needle is way too lean. Happens every time it gets tweaked too tight.

Jezmo

The metering side of the carb will not see the tank pressure. The metering diaphragm will insure that. The walbro carbs have a pump built in that makes 5 to 7 psi available to the metering side. It sounds like a tuning issue to me. Here is some tuning info posted by Ralph - AKA Antique on this forum. After tuning the high needle start on the low as follows. Set idle to about 1800, lean the low..RPM will increase..Reset speed to 1800, repeat until this procedure no longer results in rpm increase..At this point try transition, it will probably die..open low until it doesn't die on transition...fine tune from there...Re check high, a rich low will give a false reading on high.... T.O.M. has a slightly different procedure but it arrives at the same setting and that procedure can also be found here on RCU.

clivemc

i cant figure out your settings, sounds like low needle is lean (high temporary idle) but you say it fourstrokes at low rpm ???
you also say top end rpm and pick up is fine - this to me says you have the low needle waaaaay too lean and the high needle is set waaaaay too rich to compensate at high rpm...
set both needles at 1 3/4 turns out and start leaning from there on both of them...... low first then high.........

Tired Old Man

My Feedback: (1)

Better still, read the gas engine newbie sticky.......

apalsson

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Or ..... there is air leak - probably around the insulator block
Can be due to over tightening and can be due to poor workmanship in manufactoring or assembly

MetallicaJunkie

cool.. i gotta try out that trick

bbrown2828

My Feedback: (76)

i Had this same problem with my dla 56 on my yak til I got her tuned in properly and got her broken in good ... I am on my 4th dla56 sold two planes that had them in them... now got one in my pilot yak turning 7100 on a vess 23a and on a ef 300 brand new 5 flights turning 6800 on a vess 23a

Tired Old Man

My Feedback: (1)

Just take a chance in life and open up the low needle a little bit. If that is of great concern just count the amount you turned it so you can go back. You won't go back but you'll have a warm and fuzzy feeling when you get started on it.....

a1pcfixer

My Feedback: (7)

BB,

You need to get it tuned correctly.

Jody's gas engine tuning tips (pdf files);
http://www.rcuniverse.com/forum/fb.asp?m=10293852