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ProModeler Scorpion Power
Vaderluck

Senior Heliman

Melbourne - Australia

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The engine is fitted on Trex 600N DFC with Hatori pipe.
The manual recommends needle valve initial setting 2 turns. At 2 turns, I feel it is very lean so after some trial and errors I set it to 5 and half turns... yes 5 and 1/2 turns it seems to be right, no sight of rich mixture.

I am wondering why it so far off from the manual or something wrong with my setting that I miss. I use new fuel tube, good pressure in cylinder, new main bearing, carburetor is clean. Fuel is 15% nitro, 20% Klotz 198.

06-14-2016 12:34 AM
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dasd

Veteran

Carol Stream, IL

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Without a doubt something is wrong. Have you checked the fuel line and clunk in the tank? With 15% you should be at 1 1/2 turns on the needle. What's the head temp at 5 turns out?

Formerly SunFunFlyer.

06-14-2016 01:00 AM
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jackp332

Key Veteran

Claremont, Nh USA

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You are sucking air from somewhere. ..

06-14-2016 01:24 AM
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Einzelganger

Key Veteran

Campbell, Texas

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You are sucking air from somewhere. ..
Yep, or something is blocking fuel flow.

Wayne

I love the smell of nitro in the morning.
RIP Roman

06-14-2016 01:59 AM
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jschenck

rrProfessor

La Vista, NE.

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or your idle mixture is way off. Idle should be right near straight with the carb throat

06-14-2016 02:05 AM
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jschenck

rrProfessor

La Vista, NE.

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A real issue is the fuel lines inside your fuel tank. If it sat for any time with an empty tank the fuel pick up line could be soft and flattened making a high resistance to fuel flow.

Replace all your fuel lines, especially inside the tank

06-14-2016 02:07 AM
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Four Stroker

Elite Veteran

Atlanta

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Sounds like you don't have tank pressure. Nipple stopped up ? Filter clogged ? Forgot to connect it ?

06-14-2016 02:34 AM
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jschenck

rrProfessor

La Vista, NE.

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^^ +1 - that'd do it too - a ripped pressure line/clogged exhaust pressure

06-14-2016 03:10 AM
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dkshema

rrMaster

Cedar Rapids, IA

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In no particular order:

Air leak past cylinder head. Make sure the gasket ("shim" ) is in place and that the headbolts are tight.

Backplate loose or bad seal around it. Check and fix if needed.

Muffler not tight to crankcase. Tighten bolts. Run motor for short period, stop then tighten the bolts again while hot. Do this a couple of times.

Make sure the muffler pressure fitting is tight and not plugged up. Make sure fuel line between muffler and tank vent fitting is sound and has no leaks.

Make sure fuel line inside tank (and header tank) is good, and not rotten. Check klunk weights in main and header tank are clear with no obstructions.

If you use a fuel filter, make sure it is clean and not plugged up. If you use a two-piece filter, make sure the seal is good and the two halves are tight.

All fuel line should be sound with no leaks, and fits tight at all fittings.

Grommets around tank fittings are leaking, tank has crack or split in it.

Carburetor inlet nipple loose. Make sure fiber gasket is good and tighten.

Main needle valve body is loose on carb. Make sure gaskets are good then tighten.

Obstruction in spraybar. Open throttle barrel fully. Open main needle fully. Place a length of fuel line on the carburetor inlet nipple, then blow/suck on the other end. Air should flow freely. Usually if something is in the spraybar, this will pop it loose and fix the problem. Use a filter between tank and carb. Filter fuel from jug when you fill your tank.

Glow plug loose or missing copper gasket. Center post of glow plug has bad seal.

Gasket around carburetor neck and crankcase missing, bad, or carb not fully seated in crankcase.

Crack somewhere in the crankcase.

O-rings on needle valve missing or not sealing properly.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

06-14-2016 01:24 PM
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GREYEAGLE

Elite Veteran

Flat Land's

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From setting - or from your fuel jug - maybe during your re- work or your soaking -- in solvent " maybe " the needle fuel circuit port is most likely plugged with a wad of crud or snot.

Ingested something into the itty biity fuel circuit.

NO FUEL FLOW

You can pull the needle and back flush it - hold a paper towel over the needle bore to catch it to examine the culprit.

OR If really BAD > take a small section of house hold electrical appliance cord.

Strip One wire out of the multi strand copper - and clean the booger out of their.

Check your jug while your at it - NEver Know what your gona find -

Like a Box of Chocolates

greyeagle

06-14-2016 03:21 PM
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Vaderluck

Senior Heliman

Melbourne - Australia

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Thank everyone for the input. I actually made up a checklist as dkschema suggested to go over everything. I finally found there is a blockage in the outlet of header tank so restricting the fuel flow.

Now I have another issue and would like some help.
During hovering with governor off, I push up the throttle the heli climbs up with decent speed and smokes come out ok. But then if I lower throttle down suddenly/too quick, the engine struggles and almost stalls. What is causing this, is it too rich or too lean ?

07-08-2016 04:53 AM
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allns47

Key Veteran

Richmond IN.

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when u bring the throttle back up does it blow a ton of smoke out

07-08-2016 12:55 PM
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Vaderluck

Senior Heliman

Melbourne - Australia

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When push the throttle down, smoke as normal but the engine tends to stalling.

07-08-2016 01:27 PM
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JuanRodriguez

Elite Veteran

The Villages, Florida

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It's been my experience that if you were lean, the motor would just quit instead of coughing and sputtering a little before coming back to life.....

Also, when was the last time you changed your glo plug ?? Enya 3 is my preference....

And, is your fuel fresh ??? Can't tell you the number of times I've seen bad fuel give folks all kinds of fits......

Been there, done that and old enough to know better.....

07-08-2016 03:26 PM
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Gearhead

rrMaster

Vt

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with a needle that far off one of the first things you should do is to loosen the Carb and push down on it and re-tighten it, check your head bolts, check your back plate bolts

Jim
Buzz Buzz Buzz

07-09-2016 03:29 AM
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TMoore

rrMaster

Cookeville, TN

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Dave gave you good advice as well as others.

On 30% nitro the needle settings ought to be midway to just a little left on the idle and somewhere between 1.75 and 2.25 turns out on the HS needle. This all depends on the altitude you are at and what muffler. Anything really different than this is telling me that you have a fuel delivery issue.

On 15% nitro your LS needle should be a little leaner and the HS will be in the 1.5 to 1.75 range. What plug are you running and which Hatori pipe?

Delayed Response Operator Not Engaged

07-09-2016 04:51 AM
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