New OS46 FX ...difficult to start !
 

Got a lovely new OS 46 FX but the baby shore is difficult to start. Sometimes I just have to give up sometimes it starts in just 1 flick. Is it because its new.

Also strangley the needle seems to able to be tightened upto 1 turn out from zero position and the engine is still rich.

Help

New OS46 FX ...difficult to start !
 

Forgot to add ... Have run in about 2 tanks of 300ml methanol thru it. pretty richly. Any other break in instructions

New OS46 FX ...difficult to start !
 

What kind of fuel are u using .

R u using the home built fuel or a specific brand .

If hoem fuel , check the percentages.

As u have mentioned about the tightness of the needle, it is advisable to have it 2.5 turms from the closed valve position .

Another reason , coudl be, you have over flodded the carb. u woudl hve to open the plug & drain the fuel out by invertingthe plane . But before u do this make sure the valve is tighetened so all ur fuel does not leak . Now invert the aeroplane.

Before u start the aircraft, open the carb aperture full and palce ur thumb over the hole and turn the prop a coupel of times( make sure the glow plug is not plugged) to move the fuel.

Now u can start the engine .

happy Flying.

New OS46 FX ...difficult to start !
 

Check the glow plug & verify that you getting enough voltage to the plug when trying to start it.

Also does the engine seem to have good compression. Remember don't break-in an ABC type engine too rich or you can screw up the fit between the piston and sleeve.

New OS46 FX ...difficult to start !
 

Thanks Arjun I use pure methanol+castor oil mix no nitro !

Hi RC Flier whats this about not breaking it in too rich... This i need to know

OS FX .46 Hard Starting
 

My recommendations, based on my experience with this engine, in order of priority.

1.) GLOW PLUG!!!! This engine is married to the OS A3 plug -- I have seen several engines from other club members that were difficult to start and when they switched to the A3 plug all their problems dissappeared.

2.) I know your probably not using NITRO because you can't where your at. Try putting a few drops of ARMORALL in your mix. This will reduce the fuel's tendacy to foam.

3.) rcflier_gi is correct here. The OS FX .46 is an ABC engine, it does not have a ringed. You need to break this engine in at a leaner setting than you would with a ringed engine. It has to get hot to get the parts to properly settle in.

break-in
 

ABC engines should not broken-in slobbering rich and should not let to be run so rich that they "4 cycle". If you let an ABC engine run in a "4 cycle" mode it runs too cool. Running too cool doesn't let the piston and sleeve to expand properly and this causes premature piston wear and will shorten the life and power of the engine.


During break-in they should be run rich but in the "2 cycle" range for a few minutes. Let the engine cool. Repeat that step about 5 times. Then try to peak the engine. If the engine won't hold its peak then repeat the rich "2 cycle" runs a few more times.

New OS46 FX ...difficult to start !
 

I'd like to add that the 46FX should be started with a very low throttle setting (especially with an electric starter). For mine, I can leave my throttle at idle and she starts usually on first zip of starter. If I accidentally have the throttle open 1/4 or more and try to start she floods, easily, sometimes requiring that I take out the plug and dry'er out. Good luck.

New OS46 FX ...difficult to start !
 

Fisrt off, did you get the instruction manual with your engine? If not you can download a pdf copy from http://www.osengines.com/. This will answer most of your questions about break in and starting.

As far as break in is concerned, the conventional wisdom is to not run it fully 4 cycling rich. However, strangely enough OS's instruction manual for this engine actually says to do that on the first couple of tanks. I wonder if the fact that these engines are ABN (nickel) not true ABC has any effect?

The whole break in process will take a while, I think I ran about 1/2 gallon (about 2 litres) through mine real rich for 5 minute runs before I flew - slowly leaning it in after each tank. I've now got about 2 gallons (~8 litres) through it and turning a 10x7 prop on 15% nitro/18% oil fuel it is set exactly 1 turn out open on the main needle around 500 rpm below full lean. Also, I needed to close the idle needle quite a bit to get a good reliable idle.

Another thing, what percentage of oil are you using? The manual says 18% minimum is mandatory. Many commercial fuels here in the US are lower (16-17%) so I adda few ounces of castor per gallon for safety.


I've found that I can usually get it to hand start once its primed well. the method I use is:
1. Throttle open full
2. finger on card, flip until fuel reaches carb
3. flip 1-2 times more
4. finger off carb, throttle at idle
5. flip 2-3 times to get mixture into cylinder

Now attach the glow driver and flip to start. This method sometimes fails on the first start of the day but is usally sufficient thereafter.

New OS46 FX ...difficult to start !
 

hmm to rich or not too rich is the question...!

I have had a lt of fuel thru this and will start leaning it out now. Do you suggest I let her go at full throttle for the whole tank !!

New OS46 FX ...difficult to start !
 

hmm to rich or not too rich is the question...!

I have had a lt of fuel thru this and will start leaning it out now. Do you suggest I let her go at full throttle for the whole tank !!

The procedure that I followed after the first very rich runs was to lean it out a couple clicks between each run. I used wide open throttle but kept the run time short (5 min). I believe the rule of thumb is that its broken in when it will hold a steady peak rpm without fluctuating wildly.

-Jeremy

RULE OF THUMB???
 

Nope!!!

The correct rule of thumb is it is broken in when you feel like the engine is performing extremely reliable at one setting, you've got hundreds of hours logged in it, and you think maybe I can get a little more from it if I lean it out a little more. :D Another rule of thumb is its broken in when its old, tired, and simply worn out.

:p With some engine/airplane combinations the above never happens.

Now, your definition does sound to me like the one I use to determine whether its time to fly with the engine. Your definition is missing one important feature. The engine must be able to hold a steady idle without stalling out.