OS AX 46 Nitro
03-05-2012, 09:37 AM
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OS AX 46 Nitro
I have a problem with my 46 OS AX and looking for answers. I simply can not get it to idle down to what it should. I have adjusted the low speed valve but can not get it set. It will idle for a few seconds then die. Cant tell if it is rich or lean as have been both ways at "ticks" at a time. The high speed appears to not be a problem as it turns up good, just when coming back on throtle it will idle a few seconds and then die. It also seems to be leaking excessive fuel/oil. Liquid drops out of silencer along with exhaust smoke which does not appear excessive. Doesn't appear to be any leakage in the tank and it is well padded with foam. I haven't flown it since last fall but Yesterday was a fairly nice day so thought would get a little air time but dead sticked on landing two time and 4 of us spent several hours trying to get the thing adjusted without success.
03-05-2012, 10:15 AM
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RE: OS AX 46 Nitro
CHECK THE THROTTEL BARREL SPRING. THIS CAN LOOSE IT SPRINGINESS ALLOWING THE BARREL TO MOVE IN AND OUT SLIGHTLY. tHE RETINING SCREW CAN CAUSE A LITTLE WEAR IN THE SLOT IT ENAGES IN ON THE BARREL; SUFFICIENT TO CAUSE A FLUCTUATION IN IDLE SPEED/S, STRETCH IT SLIGHTLY AND RE INSTALL.
FUEL, EXCESSIVE OIL CONTENT MAY BE YOURE OTHER PROBLEM; NO MORE THAN 15 TO 18 %MAX IS NECESSARY FOR THESE ENGINES.
FUEL, EXCESSIVE OIL CONTENT MAY BE YOURE OTHER PROBLEM; NO MORE THAN 15 TO 18 %MAX IS NECESSARY FOR THESE ENGINES.
03-05-2012, 12:21 PM
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RE: OS AX 46 Nitro
Hi!
First of all you have to use 5-10% nitro in the fuel! Then use a good new glow plug like an OS 8 or Enya 3 ...or Nova rossi 3 or 4 or 5...Rossi 3 or 4...there are many others too!
Then use a 10x6 -12x4 prop. Then use an 8-10 oz tank, placed according to the "tank mounting rule"!
If you have done that and all engine bolts are tight ...then start the engine and first set the high speed needle! Remember to set it a little rich ,and at the same time holding the front of the plane straight up to check the setting! You hold the front up because this is the most delicate attitude the plane is in, like at take off! -You don't like to have the engine cut out at take of do you!?
IF the full speed setting is steady ,then..only then should you set the low speed needle (idle needle). You always set the low speed needle like this: Throttle down to idle from full throttle (throttle drum open aprox 1,5-2mm). At this throttle position the engine should keep a steady idle (2000-2500rpm) for as long as you want...then give full throttle!!! The engine should now go to full rpm without hessitation!
If it does not you have to set the idle needle! Remember! The engine can only react in two ways when trotteling up!...1. either is sputters/bludders and hesitates and perhaps dies...or ...2. it hessitates and perhaps dies! These are the only two reactions that are possible and thus it is very easy to hear when the engine does what!
If it 1. bludders and sputters and hessitates...the low soeed needle is set too rich! ...turn it in some!
If it 2. hessitates ...then the low speed needles is set too lean...open it some!
First of all you have to use 5-10% nitro in the fuel! Then use a good new glow plug like an OS 8 or Enya 3 ...or Nova rossi 3 or 4 or 5...Rossi 3 or 4...there are many others too!
Then use a 10x6 -12x4 prop. Then use an 8-10 oz tank, placed according to the "tank mounting rule"!
If you have done that and all engine bolts are tight ...then start the engine and first set the high speed needle! Remember to set it a little rich ,and at the same time holding the front of the plane straight up to check the setting! You hold the front up because this is the most delicate attitude the plane is in, like at take off! -You don't like to have the engine cut out at take of do you!?
IF the full speed setting is steady ,then..only then should you set the low speed needle (idle needle). You always set the low speed needle like this: Throttle down to idle from full throttle (throttle drum open aprox 1,5-2mm). At this throttle position the engine should keep a steady idle (2000-2500rpm) for as long as you want...then give full throttle!!! The engine should now go to full rpm without hessitation!
If it does not you have to set the idle needle! Remember! The engine can only react in two ways when trotteling up!...1. either is sputters/bludders and hesitates and perhaps dies...or ...2. it hessitates and perhaps dies! These are the only two reactions that are possible and thus it is very easy to hear when the engine does what!
If it 1. bludders and sputters and hessitates...the low soeed needle is set too rich! ...turn it in some!
If it 2. hessitates ...then the low speed needles is set too lean...open it some!
03-05-2012, 12:25 PM
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RE: OS AX 46 Nitro
Hi!
First of all you have to use 5-10% nitro in the fuel! Then use a good new glow plug like an OS 8 or Enya 3 ...or Nova rossi 3 or 4 or 5...Rossi 3 or 4...there are many others too!
Then use a 10x6 -12x4 prop. Then use an 8-10 oz tank, placed according to the "tank mounting rule"!
If you have done that and all engine bolts are tight ...then start the engine and first set the high speed needle! Remember to set it a little rich ,and at the same time holding the front of the plane straight up to check the setting! You hold the front up because this is the most delicate attitude the plane is in, like at take off! -You don't like to have the engine cut out at take of do you!?
IF the full speed setting is steady ,then..only then should you set the low speed needle (idle needle). You always set the low speed needle like this: Throttle down to idle from full throttle (throttle drum open aprox 1,5-2mm). At this throttle position the engine should keep a steady idle (2000-2500rpm) for as long as you want...then give full throttle!!! The engine should now go to full rpm without hessitation!
If it does not you have to set the idle needle! Remember! The engine can only react in two ways when trotteling up!...1. either is sputters/bludders and hesitates and perhaps dies...or ...2. it hessitates and perhaps dies! These are the only two reactions that are possible and thus it is very easy to hear when the engine does what!
If it 1. bludders and sputters and hessitates...the low speed needle is set too rich! ...turn it in some!
If it 2. hessitates ...then the low speed needles is set too lean...open it some!
First of all you have to use 5-10% nitro in the fuel! Then use a good new glow plug like an OS 8 or Enya 3 ...or Nova rossi 3 or 4 or 5...Rossi 3 or 4...there are many others too!
Then use a 10x6 -12x4 prop. Then use an 8-10 oz tank, placed according to the "tank mounting rule"!
If you have done that and all engine bolts are tight ...then start the engine and first set the high speed needle! Remember to set it a little rich ,and at the same time holding the front of the plane straight up to check the setting! You hold the front up because this is the most delicate attitude the plane is in, like at take off! -You don't like to have the engine cut out at take of do you!?
IF the full speed setting is steady ,then..only then should you set the low speed needle (idle needle). You always set the low speed needle like this: Throttle down to idle from full throttle (throttle drum open aprox 1,5-2mm). At this throttle position the engine should keep a steady idle (2000-2500rpm) for as long as you want...then give full throttle!!! The engine should now go to full rpm without hessitation!
If it does not you have to set the idle needle! Remember! The engine can only react in two ways when trotteling up!...1. either is sputters/bludders and hesitates and perhaps dies...or ...2. it hessitates and perhaps dies! These are the only two reactions that are possible and thus it is very easy to hear when the engine does what!
If it 1. bludders and sputters and hessitates...the low speed needle is set too rich! ...turn it in some!
If it 2. hessitates ...then the low speed needles is set too lean...open it some!
03-05-2012, 02:06 PM
#5
Senior Member
RE: OS AX 46 Nitro
A good way to set the low speed needle is using the pinch test.
Set the highspeed needle. Let it run full throttle to clear out the passageways. Throttle down to idle and adjust the throttle trim to get the lowest reliable idle. Let it run for a bit (15 seconds works for me). Pinch the fuel delivery tube at the carb. Yes, be careful.
When you pinch off the fuel, if the lowspeed is too rich, the idle will increase and die. It increases because the lowspeed was too rich.
If it doesn't increase, just dies, it was too lean.
Any adjustment to the lowspeed needle should only be slight when adjusting an engine that used to run without trouble. 1/16 turn is about right.
Repeat until the pinch causes just a touch of increased rpm before shutting off.
I often use a hemostat to pinch the tubing off. It's safer.
Set the highspeed needle. Let it run full throttle to clear out the passageways. Throttle down to idle and adjust the throttle trim to get the lowest reliable idle. Let it run for a bit (15 seconds works for me). Pinch the fuel delivery tube at the carb. Yes, be careful.
When you pinch off the fuel, if the lowspeed is too rich, the idle will increase and die. It increases because the lowspeed was too rich.
If it doesn't increase, just dies, it was too lean.
Any adjustment to the lowspeed needle should only be slight when adjusting an engine that used to run without trouble. 1/16 turn is about right.
Repeat until the pinch causes just a touch of increased rpm before shutting off.
I often use a hemostat to pinch the tubing off. It's safer.
03-05-2012, 04:08 PM
#6
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RE: OS AX 46 Nitro
So the engine worked right last year but doesn't now that it has sat for a while? I'd suspect (in order) bad fuel, fouled glow plug, leaky lines or fuel tank stopper, bad o rings. If it ran right with the needle settings it had last year it should still run now. Maybe not perfectly due to weather changes, but it should run.
03-06-2012, 05:24 AM
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RE: OS AX 46 Nitro
Jester, you may have something. I get a new jug and see what happens. We changed the glow plug to an OS #6. Checked the fuel tank and it looked ok, but who knows. Suspected maybe a line but they were ok. Baffling!!!
