Anwar,
The openings of one and half to two turns should hold good for any engine new or old on a fixed wing aircraft tostart with and once engine is running one can richen or lean the engine further.
Since we are talking of engine refusing to start, the low speed needle can be left alone. An engine will start and sustain even if he LSN is fully screwed in or out, only thing one may need to take care is to keep the venturi open differently from a well tuned engine.   

Hmm... that was interesting.  I did have personal experience on two different occasions where Thunder Tiger engines on cars would not start at all until the low needed was open 4 turns or above.  Only had this with TT engines, and that is why I asked the question that way.  Must be one off incidents.

mixture control screw (low speed screw) position has a direct effect on the needle control setting. a wrong mixture control setting may result in extra opening of the needle valve like 4 turns etc depending on the engine. for an old engine to work properly the carb has to be squeaky clean in the first place. also the correct pressure has to be given from the silencer to the tank for proper running.

Harish,
The LSN has no bearing when the throttle is either fully open or will have only varying affect based on how much is the barrel open or closed and that is the reason I wrote about the venturi open differently. What the LSN needle does is to obstruct (meter) the main fuel orfice when the barrel is starting to close from some where around slightly less than 1/2 open, after it is open beyond 1/2 you can peer inside the carb and see that the the two are quite apart and hence will not have any affect on each other.
If you are taling about car engines I do not have any idea but this is how it works on a two needle aero carb. There are air bleed and a special one used by Enya which uses both fuel metering and air bleed combination, which requires a full page explanation

Anwar,
The only time I have owned and used a TT engine was thier first generation 19 engine which was not much than paper weight. But then the openings mentioned are true for most modern and commonly availble engines. There might be some which might differ. Again the factor which might affect the number of turns is the pitch on the high speed needle thread. A finer thread means more number of turns and a coarser thread means lesser turn.   
 

Normally when one starts an engine, the throttle servo end points are set in such a way that the carb barrel opening is left at 1mm or 1.5mm.   At this position, the LSN is the one that is dominant in determining the fuel supply into the engine.  So how does it make sense to say that the LSN position (even fully closed) is immaterial ?   

The LSN is dominant from 0 to about 35% of the throttle range, between 35% and 60% both LSN and HSN have an impact, and above 60% it is primarily the HSN, right ? (these percentages are only approximations, just trying to put some numbers).

Anwar you are absolutely right. But then you also did not read my posts carefully. I have said even if the the LSN is fully closed the engine could be started with the venturi differently opened, not necessarily what openings we use normally.
The entire post is aimed at some one who does not have some one experienced to help him/her and by going through the thread presumably could trouble shoot the engine. Therefore I would not recommend some one fiddling with the LSN if the engine is not starting. I would rather recommend that the barrel is gradually opened a bit more and engine tried starting (if all the previous things have been checked and found correct) and if the engine starts and sustains running at more than 1/3 throttle barrel open (ball park figure only) would it mean that the time has come to fiddle with that LSN

But then we do not want to start the engine at a significantly high rpm (i.e. high throttle position) either, right ? 

Starting at high RPM is particularly nasty for helis which have clutches (while the main blades are held down by force).  Even a few seconds on high rpm can cause the clutch to grind off, and in extreme cases, the heat builds up and the clutch bell explodes (I have seen it at least once  )

Anwar,
The only thing I know about Heli is that simply put "they are not airplanes".
So all my comments and suggestion necessarily only pertain to fixed wings. 

Most TT car engines default start setting are 2.5-3 turns on HSN and about 4.5-5 turns on LSN. This wll be a very rich setting, will help to start, but will die down unless corrected.

Our member Deepak Chopra (b4ggu) responded on Facebook to this thread with the following.

"A couple of drops of petrol NO MORE have known to start some of my stubborn engines."

Interesting...  can you explain more ?


PS: We have no feed from Twitter/Facebook back into RC India at this time, that is why I am posting this manually here.

Interesting. Did he mean glow engines when he said stubborn engines?
One of the tricks for starting diesel engines during a chilly morning was to keep it wrapped in wollen rag, started much easily 

This reminded me with a problem I had with a relatively new .91 FX last year. As usual, I primed and attempted to start ( on idle ). and the engine just would not start. However when i increased throttle to 1/2 then the engine started, though died when i idled it back. Ran OK on full throttle though. I had to open the LSN to get it to start ( and idle ) properly.
What was surprising was , that I had never touched the LSN on that engine before, and the last it flew was a year back. So not sure why the LSN needed to be touched/ opened.
Now, after a year from this incident, I started the engine again last weekend. And again the same problem seemed to occur. I had to open the LSN half turn to get it to run on idle. But after running for a minute or so , felt that the idle was too rich, so closed that 1/2 turn back to get it to where it was originally.
I felt that surprising, as normally i would not have access to LSN, if the engine was cowled..
Perhaps the carb needs to be cleaned ?

I assume you use castor as lubricant. The LSN needle (or rather sleeve) can get clogged with castor residue. This is 99.99 the cause in your case as the engines wereleft unrun for quite sometime.
This should have gone away after the engine had time to heat up and maybe burn of the residue.
Yes time to clean your carb   

Keep a 20 cc plastic syringe in your field kit for checking out fuel issues, blowing in/ sucking fuel out of the various line. DO NOT USE YOUR MOUTH TO BLOW/ SUCK- FUEL CONTAINS METHANOL.

tHE WAY I WOULD GO ABOUT IT IS IN STAGES
1. DOES THE ENGINE RUN on prime alone.
Set up the engine after checking the that the plug glows, and prop turns over easily.
Disconnect all fuel lines.
Put about 1/4 ml of fuel into the carb through the  venturi. Turn the prop over a few time , attach the glow booster and flick the pro / use starter to start the engine.
If all is well with the engine, it should start, run for 10 seconds or so and die out.
Otherwise think of glow plug, compression and engine related issues.
no point going to the next step if step 1 fails.
If the engine turns over easily, but becomes tight after the fuel is put in, the it is flooded.
Note- 20cc syringe and 1/4 (0.25) cc of fuel max. about 10 drops is fine.
By the way- the fuel may be bad. borrow fresh fuel  and try agan. or the glow booster discharged.

Now step 2
Is the tank set up okay. Fill up 1/2 the tank.
2 tube tank
Use the  syringe to blow air in through the muffler pressure port. Fuel should come out of the  fuel tube.
Then suck fuel out of the fuel tube- there should be no air bubbles.
If this is okay, the tank is fine. If not take the tank apart check the clunk and fuel tubes. Pressurize each tube with the syringe and look for blocks, or leaks.
3 tube tank
with the tank 1/2 full, and plane flatand all 3 tubes open., suck fuel out of all 3 tubes- fuel should come out of 2 and air out of the third. The one that air is coming out of is the muffler pressure tube.

Invert the plane. Now suck the  first 2 tubes.( from which fuel came out of). Fuel will come out of one- the fuel line and air out of the other- the filling line. if fuel comes out of both ( don't test the muffler pressure tube now it is alreadyidentified.), then both have clunks and either can be connected to the carb.
Fuel line to carb, pressure line to muffler and close the fill/emptyline.

If there is any issue take the tank apart and check.
Surf the net for information on tank set up and if you still can't understand it, get help from someone who does.

if all is well, go to step 3
 Leave the LOW SPEED NEEDLE as it is.
ensure that the carb barrel turns easily and fully from full open to full closed. Conect the syringe  in it to the fuel inlet of the carb. Open the high speed needle about 2 to 2.5 turns from fully closed.
See if you can easily inject air into the carb with the syringe. Then try to inject fuel into the carb with the syringe. If you can't there is rubbish blocking the fuel inlet. sort it out. remove the carb and try to flush out the rubbish after completely removing the HSNeedle.
Just to ensure that the whole fuel plumbing is okay - inject air into the fuel tank thorugh the pressure tube- fuel should enter the engine through the carb- just be sure you not flood the engine, if you do clear it.
Now connect the fuel line from the tank to the carb and prime the engine by turning the prop without the glow booster
The engine should now start with the carb barrel 1/3 open.
The high speed needel can the be adjusted.
Going in this stepwise manner should ensure that we are dealing with problems in a logical manner.
If the engine does not even fire on prime, no point fiddling with the low speed needle.
hope this clarifies rather than confuses the issue.
Avijit
. 
 

The syringe is a nice touch    No wonder one improvises using the tools of his trade   

We get long wet and muggy winters when it gets dark at 4pm. As from Sept / Oct a lot of us stop flying outdoors and resume in March/ April.
Winter months do offer a chance of indoor electric flying to some of us. This does not apply to the hard core RC Flyers though. You see them at the flying fields even after snow with their electric and nitro models.
Coming back to the point, when the fuel has been left standing in the garage for those cold winter months, it is a common problem that the engines will not start as the fuel has absorbed moisture.
At this point, a few drops of petrol in half a gallon can help.

Hello RC lovers,
        Today i tried my best to start my ASP .25 but was able to start only once. Its a new engine. I read many threats, but none can help me. Complete day trial gave me a start only once, which lasted for about three minutes. then after stopping it, i found that fuel ran back to pipes.
please note my procedure.

1:After setup, i closed the upper end of carb, and gave engine about five fricks, until fuel seemed to reach the carb. Then again two fricks for fuel to go in the engine.

2:Ignited glow plug using 1000mah nicd cell.

3:Gave engine many two-three fricks, and tried for about 30 mins, adjusting the needles every time. A few times engine even backed up.

4:Even warmed up once using hot blower, as i read in on of the threats.

5:Finally it started once, we enjoyed the roar, and played with throttle controls to acclerate and deacclerate, simultaneously adjusting the remote needle as well.It went on for about 3hree minutes.

6:Finally i found by adjusting the flow through remote needle, that lesser the flow, more the pickup, of engine..

7:I stopped the engine, to have a start again. And i found that fuel backed in the tank during the next trial.

8:Repeated the procedure(except warming up), and finally made a mess with the needle adjustments.I even disturbed the one in carb, using a small screw driver.

Then wasted whole day, engine did not start. My younger  bro even had a cut on finger when engine backed up.

Please note that i have used chicken stick method for starting. And fuel: 70% methanol(obtained from lab equipment shop)+ 30 % castor oil(natural oil filtered one)


Please help me to adjust the needles again, the one in the carb, as well as the remote needle.
And suggest me if im wrong in my procedures.

And please tll me if there is some other step im missing..
I dont want to use engine starters.

Thanks in advance..

Are you in Lucknow itself, or far ?  Reading the description, the simplest would be to meet up with one of the experienced glow flyers around. 

For a new engine, your starting point on needle setup would be the values suggested in the manual.

Unfortunately, i didnt get any manual. ill try to find it out on some link.
Help if someone already have the link for the manual..
Some LHS provide the manual also in pdf formatt. I dont remember the name of LHS.

Yes sir im in lucknow

Since you have had soo much trouble, may I suggest a step wise method of going about it.
Fuel 80% methanol and 20% castor oil. To 135ml of the fuel you already mixed add 65ml of pure methanol to make a total of 200ml.
Check that the booster is adequately charged. Remove the glow plug from the cylinder head and confirm that it glows brightly when connected to the battery. then re install,do this carefully so as not to damage the threads..
Check that you are using the recommended prop. 9x6 should be okay and it should be fitted so that compression is felt at the 2 o'clock position.
Practise a few sharp flicks. you must have done a lot of that , but be sure the flick is sharp- with a chicken stick of course.
Invest in a 10ml plastic disposible syringe. do NOT directly blow with your mouth into any tubing/tank that contains methanol. GOES WITHOUT SAYING DON'T EVEN THINK OF SUCKING ON A PIPE TO DRAW METHANOL CONTAINING FUEL.
HENCE the 10ml plastic syringe.
I assume you have a fuel tank that is connected appropriately.
The tube with the clunk connected to the fuel inlet of the carb. the other tube( air vent tube connected to the muffler pressure port.
Engine is reliably mounted on a test stand/ model.
Fill up the 10ml syringe with3 ml of fuel.
Do not connect the fuel tank to your motor.
Put 3 drops of fuel/ not more down the open barrel of the carb. Through which air enters. The opening you blocked with your finger to prime the engine.
Flick the prop over 3 times.
Attach your glow booster now.
FUEL TANK DISSCONNECTED.
Flick the engine over till it runs.
It will start-run for a few seconds and then stop.
Do not pour more fuel down the carb because it isn't starting, unless you have flicked it at least 20 times.
so the routine is 3 drops of fuel, flick the engine till it starts or 20 flicks- which ever is earlier, then repeat process.
If it doesn't start after 3-4 attempts like this, the engine is flooded.
Remove the glow plug and flick the engine till all the fuel comes out.
Remember the engine burns fumes of the fuel not the liquid stuff.

If you got this right,you have a working engine and you have learned the technique of hand starting a glow engine-which is something great.
All you need to do is to tune the carb.
 

Abhay
I am sure you have buggered up the settings, and even possibly run it too lean (your statment "Finally i found by adjusting the flow through remote needle, that lesser the flow, more the pickup, of engine") gives me that feeling.
Besta dvice, get someone who knows to start and run in your engine before it is too late (if it not already too late)
Sorry for sounding pessemistic but all what you wrote above point to the dreaded fact

http://media.globalhobby.com/manual/210625.PDF
the link to magnum 25 manual which is th esame as ASP 25.
for High speed needle- the one at the back
Close the needle completely then unscrew it 2 1/2 turns.
For low speed needle- the little one inside the Carb which you turned with a little screw driver which you should not have
Read and understand the instructions carefully
Open the throttle so the barrel is fully open.
Screw in the little low speed needle till it is fully closed. then unscrew it 3 full turns. And DO NOT MEDDLE  with it again except under competant supervission.
I hope this helps you.
It should if you follow the step wise instructions and don't skip steps.
I follow the first part of the instructions with every new engine.
Only after i have got the engine running on prime do i connect the fuel tank and start the engine etc.

Please let us have a feed back on how you have fared.
you will have learnt a lot after this experience.
download and print the engine manual
regards and good luck
Avijit
p.s Anwar: Could we have something like this as a sticky topic and insist that all beginners read it.

We already have a thread that has been "sticky-ied" :

http://www.rcindia.org/fuel-and-engines/tip-dealing-with-a-glow-or-nitro-engine-that-refuses-to-start/

I am thinking of merging this one into that... comments ?

Capt. Manish is right. But since you couldn't run the engine except once, there is no permanent damage
Just try not to fiddle with the needles too much the first try arround.
if you have faithfully followed the instructions- not mine, the ones in the magnum manual,and still can't get the engine to run, then you will need expert advice.
Avijit
P.S.
Thanks anwar. Abhay please read the link as well. Good idea to merge both threads.
I feel most manuals do not suggest that the engine first be fired up on prime before attaching on the fuel lines.
I learnt it from starting diesels and think it is good practise.