schokshi

Hi,
I am new to gas engine. This is my first gas engine. I have installed this engine in old Hangar 9 ultra stick 120. When i first started it, with factory needle setting, i could never get idle below 2400 and with 17x10 3 blade prop i was getting over 9,000 RPM so i thought it was too lean and i started adjusting needles.
Now problem is, i have set low speed to 1.1 turns & high speed to 1.75 turns (i wanted to start leaning out) however i still can only get 2500 RPM as a reliable idle any below that i get "knocking". My understanding is that i should get around 1800 RPM as idle.

Can someone help me resolve "Knocking" issue & get reliable idle, also is there a way to know generally what RPM i should get with 17x10 3Blade prop so i can use that as guidance.

Thanks in advance for your time and help.

schokshi

Also, wanted to let you guys know that i am using a spark plug that came with an engine its DLE brand and using 93 octane 30:1 gas/oil mix

AGMUSA

My Feedback: (1)

You may need keep rich the low needle and make the idle speed around 1800 rpm. or change bigger prop. one way or other may work. good luck

ahicks

My Feedback: (2)

I'd agree. Going richer on the LS will slow the engine, and a prop allowing the engine to turn 9K on the ground might be a little small?

If the carb is closing completely and the engine can't get it's air from anywhere else, wondering why you can't get it to slow down? You've removed the screw that is normally used to control idle speed, right? The servo endpoint set to pull the carb closed all the way? Servo seems to be functioning OK? Some othe DLE's I've messed with have had the screw that holds the carb plate positioned on the shaft loosen, allowing the plate to be misaligned. Might be tempted to check that as well?

schokshi

Initially idle screw was left as it came from factory and I have now turned it out so I can close carb more, it will drop RPM but that's when knocking starts. I am relying on optic kill switch to shut down engine as I have no visual reference to carb opening at idle. Is there any trick there?

schokshi

Also instructions on TBM site says to use lower load during breakin. Recommended was 19x8 2 blade so I am using 17/10 3 blade prop

ahicks

My Feedback: (2)

The idle speed screw should be completely removed to assure it is not in play - ever. You want your servo to control idle speed. If set up properly it should be able to shut the engine down by itself - by completely closing the throttle - just like a glow engine is shut down.

Differing opinions regarding the need for a 'break in' prop. 9k is too many rpm. though

The only thing I can think of that might cause the backfiring might be a lean condition.

schokshi

Thanks, i have removed idle screw and adjusted end points so that full down trim on throttle completely closes carb with slight hint of binding. Generally how many clicks you open for from close for gas engine for idle opening?

ahicks

My Feedback: (2)

This will vary quite a bit from plane to plane, but something around 1/8 throttle should start it OK?

All Day Dan

My Feedback: (5)

schokshi,
You’re better off using one of your transmitter’s switches as a cut switch or else you are going to have to reset your idle trim every time you use it as a cut. Dan.

tevans55

Get rid of the dle plug. Replace with a NGK cm6 plug.

schokshi

Thanks all for your replies, i have replaced DLE spark plug with NGK spark plug, also applied some dielectric grease on top, checked spark & it is working fine. low speed was 1 3/4 out & high speed was about 2 turns out, now when i close choke, engine will not pop at all.

Does anyone have any idea what should i check next? is there any place i can send in my engine to have it checked out?

3136

Try this,
Check ignition battery voltage first

Choke closed
Throttle set to 1/8 to 1/4 (you wont get fuel in if the throttle is fully closed)
flip the prop so you can see fuel moving up the line (maybe 4-6 times)
turn ignition on
flip till engine pops
throttle back to just above idle position
choke off, flip till start