95 AX run in problems.
03-04-2010, 01:03 AM
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95 AX run in problems.
Hiya Bax (and others),
I've recently fitted a brand new 95 AX to my also new extra. I followed the run-in procedure given in the manual using a 15x6 prop, and 20% synthetic / 5% nitro fuel. Engine using standard muffler mounted at 270 degrees so the muffler is below the engine.
During run in (on the ground, cowl off), where I was running VERY rich, the engine started to show signs of overheating. (RPM drops). Next run (from cold) was with cowl on but again rich and with some simply baffling to direct airflow. It was warm but I did not dare run it for too long.
Someone convinced me that it would be better in the air but on maiden it dead sticked after a few minutes. I assume it was too hot still. Each time I checked it was hot at the head and muffler but the crank case was quite cool.
I took the engine out and mounted on a test mount, tried a few more rich runs but no longer than about 4 minutes each. After each run I think the head was hot but the crank case temp felt fine.
Now it's back in the plane and I've made sure there are larger exit holes in the bottom.
Ambient temp is about 80 degrees F. The engine has had perhaps 1/8th to 1/4 of a gallon of fuel.
Basically my question is, how hot would you expect the head to get (especially during run-in). After a 5 minute run, if I touch the head with a wet finger, the head is sizzling (which I assume to be too hot). But I am afraid to run it for more than a few minutes because I do not wish to damage the engine. Since the crank is quite cool, should I just keep running it a little rich and slowly extend the run time or would you suggest that the head should not be that hot ever?
15x6 turns it at about 9500 rpms but I've heard of others getting over 10k with that prop. Would be willing to drop down to 14x6 or 14x8 if necessary.
I'm hoping that all I am seeing is excess friction while the ring beds in.
Thanks for your time.
I've recently fitted a brand new 95 AX to my also new extra. I followed the run-in procedure given in the manual using a 15x6 prop, and 20% synthetic / 5% nitro fuel. Engine using standard muffler mounted at 270 degrees so the muffler is below the engine.
During run in (on the ground, cowl off), where I was running VERY rich, the engine started to show signs of overheating. (RPM drops). Next run (from cold) was with cowl on but again rich and with some simply baffling to direct airflow. It was warm but I did not dare run it for too long.
Someone convinced me that it would be better in the air but on maiden it dead sticked after a few minutes. I assume it was too hot still. Each time I checked it was hot at the head and muffler but the crank case was quite cool.
I took the engine out and mounted on a test mount, tried a few more rich runs but no longer than about 4 minutes each. After each run I think the head was hot but the crank case temp felt fine.
Now it's back in the plane and I've made sure there are larger exit holes in the bottom.
Ambient temp is about 80 degrees F. The engine has had perhaps 1/8th to 1/4 of a gallon of fuel.
Basically my question is, how hot would you expect the head to get (especially during run-in). After a 5 minute run, if I touch the head with a wet finger, the head is sizzling (which I assume to be too hot). But I am afraid to run it for more than a few minutes because I do not wish to damage the engine. Since the crank is quite cool, should I just keep running it a little rich and slowly extend the run time or would you suggest that the head should not be that hot ever?
15x6 turns it at about 9500 rpms but I've heard of others getting over 10k with that prop. Would be willing to drop down to 14x6 or 14x8 if necessary.
I'm hoping that all I am seeing is excess friction while the ring beds in.
Thanks for your time.
03-04-2010, 10:34 AM
#2
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RE: 95 AX run in problems.
If the engine is running VERY rich, it cannot overheat if it's getting cooling airflow over the fins. 20% oil content is good, and would give your engine excellent lubrication. The prop is quite a bit on the large size, but within what O.S. suggests...they use very large props for noise reduction. We run smaller props because noise isn't as much a factor in the U.S.
When you run the engine, it is normal for the cylinder head to become hot enough to cause severe burns if it contacts flesh. You cannot go by temperature.
If the engine is running very rich and it tends to drop in RPM, we'd consider leaning the high-speed needle. It's likely bogging-down because of too much fuel, rather than not enough.
One thing that can cause the engine to go lean when the needle is set very rich on the ground is inadequate fuel flow. That can be caused by too-small fuel line inside diameter. If that's the case, then you'll need to re-plumb the entire fuel system from clunk to engine with tubing/line that has a larger inside diameter. Not an uncommon happening.
You can run the engine at higher RPM for better power...into the high 11,000's. That won't hurt it, just make it louder. To go there would take something like a 13 x 8 propeller or so, which is what the older .90-.91 engines used to use. Only in the past decade or so, has O.S. gone to big propellers to make things less noisy. Of course, you get less power, too.
When you run the engine, it is normal for the cylinder head to become hot enough to cause severe burns if it contacts flesh. You cannot go by temperature.
If the engine is running very rich and it tends to drop in RPM, we'd consider leaning the high-speed needle. It's likely bogging-down because of too much fuel, rather than not enough.
One thing that can cause the engine to go lean when the needle is set very rich on the ground is inadequate fuel flow. That can be caused by too-small fuel line inside diameter. If that's the case, then you'll need to re-plumb the entire fuel system from clunk to engine with tubing/line that has a larger inside diameter. Not an uncommon happening.
You can run the engine at higher RPM for better power...into the high 11,000's. That won't hurt it, just make it louder. To go there would take something like a 13 x 8 propeller or so, which is what the older .90-.91 engines used to use. Only in the past decade or so, has O.S. gone to big propellers to make things less noisy. Of course, you get less power, too.
03-04-2010, 07:36 PM
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RE: 95 AX run in problems.
ORIGINAL: Bax
If the engine is running VERY rich, it cannot overheat if it's getting cooling airflow over the fins. 20% oil content is good, and would give your engine excellent lubrication.
If the engine is running VERY rich, it cannot overheat if it's getting cooling airflow over the fins. 20% oil content is good, and would give your engine excellent lubrication.
The prop is quite a bit on the large size, but within what O.S. suggests...they use very large props for noise reduction. We run smaller props because noise isn't as much a factor in the U.S.
When you run the engine, it is normal for the cylinder head to become hot enough to cause severe burns if it contacts flesh. You cannot go by temperature.
One thing that can cause the engine to go lean when the needle is set very rich on the ground is inadequate fuel flow. That can be caused by too-small fuel line inside diameter. If that's the case, then you'll need to re-plumb the entire fuel system from clunk to engine with tubing/line that has a larger inside diameter. Not an uncommon happening.
Again the engine ran too hot.
I know this is not a troubleshooting forum, but I'm still concerned that there was something wrong from the start. I've never had problems like this with my other OS engines (a copy of 46's, and an older 60 size). Before I decide to send it back I'm going to give some guys at the club a good hard look at it. If that fails, would there be anything that you would recommend I check before doing that? I've got a background in car mechanics having rebuilt many engines and gearboxes in the past, but the most I've ever done to a glow engine is pull apart the carby for cleaning.
Actually on, that note, I'd love to find out how to do some work on model engines. I have some very old OS Max engines that could do with being stripped and cleaned. Are thinks like head bolt torque settings important on engines this small? Is there any good reading matter on this subject, OS service manuals etc?
Thanks for your time.
03-10-2010, 09:58 AM
#4
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RE: 95 AX run in problems.
We still find it difficult to believe an engine running blubbery-rich will overheat. If it is slowing-down and stopping, then it may be too rich and loading up with excess fuel. The only other thing is fuel line. We'd suggest fuel line with a larger inside diameter. That also includes drilling the clunk in the tank to a larger I.D., and using larger brass tubing in the tank. Many tanks have fuel passages that are just to small for larger engines. Some of them are marginal for even .61-size engines.
We tend to prop the engine to run in the 11,000's. O.S. uses large props because of strict noise regulatioin at Japanese model airfields. They told us the engine will run nicely in the mid-11,000's, but be noisy. We find excellent throttle response at that RPM.
One final thought...if your fuel is old, the synthetic oil may have become degraded. We'd suggest brand-new fuel, and one that has a significant part of the oil package containing castor oil. Castor is still just about the best all-purpose lubrication for model engines. It's just messier on the model, is all.
[edited for typos I found]
We tend to prop the engine to run in the 11,000's. O.S. uses large props because of strict noise regulatioin at Japanese model airfields. They told us the engine will run nicely in the mid-11,000's, but be noisy. We find excellent throttle response at that RPM.
One final thought...if your fuel is old, the synthetic oil may have become degraded. We'd suggest brand-new fuel, and one that has a significant part of the oil package containing castor oil. Castor is still just about the best all-purpose lubrication for model engines. It's just messier on the model, is all.
[edited for typos I found]
03-10-2010, 06:31 PM
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RE: 95 AX run in problems.
Thanks for your advice. Today with the cowl off and the engine again very rich, the engine spluttered and died about 4 minutes in. From the time I noticed a drop in power to when it died was about 10-15 seconds.
Unfortunately I could not make it back to the landing strip and my undercarriage separated from the fuse on landing in the boggy soil (we've had a lot of rain lately).
The break was very clean and I expect to be able to re-glue the UC plate without too much effort.
I'm going to take this opportunity to totally re-do the fuel system as you recommend. I plan to do the following:
[ul][*] Remove fuel tank and install larger lines. This will require larger pipes and clunk line.[*] Use the 3rd line as a filler. Currently I have a du-bro fuel filler attached to the fuel feed line.[*] Reduce the fuel line overall length.[*] Remove carby and clean thoroughly, in case there is something blocking the high-speed inlet.[*] Switch to new fuel, nitro and coolant.
[/ul]
I am also tempted to install the fuel filter on the filler line, rather than in the plane itself.
I've not got a lot of time to work on this in the coming weeks so perhaps while I have it all apart I might take the opportunity to once again mount it on the test stand and test different fuel combinations. I know you said head temp was not a good indicator but, since I have temperature measuring equipment, could you give me some advice on upper temps (of the head)? If the head is still relatively cool but it's dropping the revs then it proves your high-end richness idea does it not? Also, all I really want to know is at what point should I stop running the engine?
I hope it's still appropriate to ask this information on this forum. I've had very good experience with OS engines in the past so I can only assume the problem will present itself eventually.
Thanks again for your time.
Unfortunately I could not make it back to the landing strip and my undercarriage separated from the fuse on landing in the boggy soil (we've had a lot of rain lately).
The break was very clean and I expect to be able to re-glue the UC plate without too much effort.
I'm going to take this opportunity to totally re-do the fuel system as you recommend. I plan to do the following:
[ul][*] Remove fuel tank and install larger lines. This will require larger pipes and clunk line.[*] Use the 3rd line as a filler. Currently I have a du-bro fuel filler attached to the fuel feed line.[*] Reduce the fuel line overall length.[*] Remove carby and clean thoroughly, in case there is something blocking the high-speed inlet.[*] Switch to new fuel, nitro and coolant.
[/ul]
I am also tempted to install the fuel filter on the filler line, rather than in the plane itself.
I've not got a lot of time to work on this in the coming weeks so perhaps while I have it all apart I might take the opportunity to once again mount it on the test stand and test different fuel combinations. I know you said head temp was not a good indicator but, since I have temperature measuring equipment, could you give me some advice on upper temps (of the head)? If the head is still relatively cool but it's dropping the revs then it proves your high-end richness idea does it not? Also, all I really want to know is at what point should I stop running the engine?
I hope it's still appropriate to ask this information on this forum. I've had very good experience with OS engines in the past so I can only assume the problem will present itself eventually.
Thanks again for your time.
03-11-2010, 10:01 AM
#6
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RE: 95 AX run in problems.
Well, frankly, we don't use temperatures at all...ever. We rely on how the engine is performing based upon RPM and sound. Temps are unreliable because they will vary with outside air temperature, fuel used, prop used, muffler used, and so on. We start out by setting the needles to known-rich settings and go from there.
Basically, the needles are set to "stupid rich", and then leaned. We may have to start the engine at 1/4-throttle or so. We keep the battery lead on until we get to full throttle and then start to lean the high-speed needle. We don't even try to adjust the low-speed needle until we can get the high-speed needle set. If the low-speed needle is too lean, it can affect the setting of the high-speed needle. For almost all engines, you set the high-speed first and then the low-speed.
Basically, the needles are set to "stupid rich", and then leaned. We may have to start the engine at 1/4-throttle or so. We keep the battery lead on until we get to full throttle and then start to lean the high-speed needle. We don't even try to adjust the low-speed needle until we can get the high-speed needle set. If the low-speed needle is too lean, it can affect the setting of the high-speed needle. For almost all engines, you set the high-speed first and then the low-speed.
04-13-2010, 02:25 PM
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RE: 95 AX run in problems.
ORIGINAL: MrFollies
Thanks for your advice. Today with the cowl off and the engine again very rich, the engine spluttered and died about 4 minutes in. From the time I noticed a drop in power to when it died was about 10-15 seconds.
Unfortunately I could not make it back to the landing strip and my undercarriage separated from the fuse on landing in the boggy soil (we've had a lot of rain lately).
The break was very clean and I expect to be able to re-glue the UC plate without too much effort.
I'm going to take this opportunity to totally re-do the fuel system as you recommend. I plan to do the following:
[ul][*] Remove fuel tank and install larger lines. This will require larger pipes and clunk line.[*] Use the 3rd line as a filler. Currently I have a du-bro fuel filler attached to the fuel feed line.[*] Reduce the fuel line overall length.[*] Remove carby and clean thoroughly, in case there is something blocking the high-speed inlet.[*] Switch to new fuel, nitro and coolant.
[/ul]
I am also tempted to install the fuel filter on the filler line, rather than in the plane itself.
I've not got a lot of time to work on this in the coming weeks so perhaps while I have it all apart I might take the opportunity to once again mount it on the test stand and test different fuel combinations. I know you said head temp was not a good indicator but, since I have temperature measuring equipment, could you give me some advice on upper temps (of the head)? If the head is still relatively cool but it's dropping the revs then it proves your high-end richness idea does it not? Also, all I really want to know is at what point should I stop running the engine?
I hope it's still appropriate to ask this information on this forum. I've had very good experience with OS engines in the past so I can only assume the problem will present itself eventually.
Thanks again for your time.
Thanks for your advice. Today with the cowl off and the engine again very rich, the engine spluttered and died about 4 minutes in. From the time I noticed a drop in power to when it died was about 10-15 seconds.
Unfortunately I could not make it back to the landing strip and my undercarriage separated from the fuse on landing in the boggy soil (we've had a lot of rain lately).
The break was very clean and I expect to be able to re-glue the UC plate without too much effort.
I'm going to take this opportunity to totally re-do the fuel system as you recommend. I plan to do the following:
[ul][*] Remove fuel tank and install larger lines. This will require larger pipes and clunk line.[*] Use the 3rd line as a filler. Currently I have a du-bro fuel filler attached to the fuel feed line.[*] Reduce the fuel line overall length.[*] Remove carby and clean thoroughly, in case there is something blocking the high-speed inlet.[*] Switch to new fuel, nitro and coolant.
[/ul]
I am also tempted to install the fuel filter on the filler line, rather than in the plane itself.
I've not got a lot of time to work on this in the coming weeks so perhaps while I have it all apart I might take the opportunity to once again mount it on the test stand and test different fuel combinations. I know you said head temp was not a good indicator but, since I have temperature measuring equipment, could you give me some advice on upper temps (of the head)? If the head is still relatively cool but it's dropping the revs then it proves your high-end richness idea does it not? Also, all I really want to know is at what point should I stop running the engine?
I hope it's still appropriate to ask this information on this forum. I've had very good experience with OS engines in the past so I can only assume the problem will present itself eventually.
Thanks again for your time.
04-13-2010, 03:59 PM
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RE: 95 AX run in problems.
I was curious the other day and brought my infrared temp gun home. When I landed I checked the head temp and it registered 148 deg f. (this is a 55ax flown for 12 minutes.)
04-13-2010, 08:08 PM
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RE: 95 AX run in problems.
ORIGINAL: DenverJayhawk
I had the EXACT same problems that you described when breaking in my 95AX. I found that the included #8 glow plug was not hot enough, no matter how lean or rich I set the high speed needle. I then tried a A3 plug and still had the same results. Then the club president said to put on an OSF plug. Viola. Engine runs like a champ now. I'm using an APC 14x8 and 14x6 prop and get about 9000-9300 RPM a few clicks on the rich side of max lean setting on 15% Cool Power. Before you tear apart your plane and fuel tank troubleshooting, try an OSF plug.
I had the EXACT same problems that you described when breaking in my 95AX. I found that the included #8 glow plug was not hot enough, no matter how lean or rich I set the high speed needle. I then tried a A3 plug and still had the same results. Then the club president said to put on an OSF plug. Viola. Engine runs like a champ now. I'm using an APC 14x8 and 14x6 prop and get about 9000-9300 RPM a few clicks on the rich side of max lean setting on 15% Cool Power. Before you tear apart your plane and fuel tank troubleshooting, try an OSF plug.
I switched fuel as well and things seem a little better but the problems are definitely not over. I was going to just try a new OS number 8 but I have a brand new (supplied with engine) OS F I can try as well.
Do you know where the A3 is in relation to the 8 and the F? I have some of those I can try as well but I'll see what happens with the F first.
04-16-2010, 10:29 AM
#10
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RE: 95 AX run in problems.
The 5% nitro fuel is a low-nitro fuel, which is why a Type F may work...just make sure that the longer F plug doesn't touch the top of the piston. Please realize that any temperature numbers given to you by anyone else are not relevant to your installation. A model engine will normally get hot enough to cause a severe burn when touched near the exhaust port or on the head...that's normal.
With higher nitro, 10%-15%, a #8 or #A3 plug will be just fine. Even with 5% fuel, they should do the job. If they don't, then something's very wrong, and you should put the engine on a test stand with everything in the open and correctly-positioned to see what's going on. If the engine won't run when on a test stand, mounted upright, with the fuel tank as close as possible, then the engine very likely is low on compression or is not sealing properly, somewhere.
With higher nitro, 10%-15%, a #8 or #A3 plug will be just fine. Even with 5% fuel, they should do the job. If they don't, then something's very wrong, and you should put the engine on a test stand with everything in the open and correctly-positioned to see what's going on. If the engine won't run when on a test stand, mounted upright, with the fuel tank as close as possible, then the engine very likely is low on compression or is not sealing properly, somewhere.
04-17-2010, 07:24 PM
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RE: 95 AX run in problems.
ORIGINAL: Bax
The 5% nitro fuel is a low-nitro fuel, which is why a Type F may work...just make sure that the longer F plug doesn't touch the top of the piston. Please realize that any temperature numbers given to you by anyone else are not relevant to your installation. A model engine will normally get hot enough to cause a severe burn when touched near the exhaust port or on the head...that's normal.
With higher nitro, 10%-15%, a #8 or #A3 plug will be just fine. Even with 5% fuel, they should do the job. If they don't, then something's very wrong, and you should put the engine on a test stand with everything in the open and correctly-positioned to see what's going on. If the engine won't run when on a test stand, mounted upright, with the fuel tank as close as possible, then the engine very likely is low on compression or is not sealing properly, somewhere.
The 5% nitro fuel is a low-nitro fuel, which is why a Type F may work...just make sure that the longer F plug doesn't touch the top of the piston. Please realize that any temperature numbers given to you by anyone else are not relevant to your installation. A model engine will normally get hot enough to cause a severe burn when touched near the exhaust port or on the head...that's normal.
With higher nitro, 10%-15%, a #8 or #A3 plug will be just fine. Even with 5% fuel, they should do the job. If they don't, then something's very wrong, and you should put the engine on a test stand with everything in the open and correctly-positioned to see what's going on. If the engine won't run when on a test stand, mounted upright, with the fuel tank as close as possible, then the engine very likely is low on compression or is not sealing properly, somewhere.
The engine ran well on my four stroke mix with the type F plug (My mix is 15% nitro, 18% klotz synthetic).
I had 3 good 7 minute flights with this setup.
I'll try a new 8 with a little less Nitro to see what happens. Is there much difference between the A3 and the No. 8 plugs? I have a few spare new ones of each. It would be good to know that I can use them interchangeably.
09-11-2010, 05:41 PM
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RE: 95 AX run in problems.
I have a new 95ax that I can't get to run for a flight. It runs fine at full throttle but quits everytime I back it off to half throttle in the air. Transition and idle
good on the ground. Running 15% nitro fuel. Have tried #8,A6,and F plugs all with no resolution. I've replumed the tank, drilled out the pressure tap a little and even put a one way valve to keep tank pressure. I've been using glow engines for a long time and can't figure this out. The Supertigre91 I took off this airplane ran great. Today talking to another member at the field today, he told me he gave up on trying to get his os 95 to run recently. Is the cylinder plating
coming off already??
good on the ground. Running 15% nitro fuel. Have tried #8,A6,and F plugs all with no resolution. I've replumed the tank, drilled out the pressure tap a little and even put a one way valve to keep tank pressure. I've been using glow engines for a long time and can't figure this out. The Supertigre91 I took off this airplane ran great. Today talking to another member at the field today, he told me he gave up on trying to get his os 95 to run recently. Is the cylinder plating
coming off already??
09-13-2010, 09:09 AM
#13
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RE: 95 AX run in problems.
If the engine quits when you reduce the throttle, it's not set correctly or not fully-broken-in. It cannot have plating come off the liner because the engine uses a piston ring and has no plating. It's a steel liner.
What prop and RPM are you running?
A one-way valve between the muffler and the tank usually makes running worse. You need to allow the tank to depressurize when you come off the throttle or you'll never get your idle mixture set correctly.
Is the fuel tank in the right position? The centerline of the tank should be at the same level as the center of the carburetor or no more than 3/8" lower. A too-low or too-high tank can cause problems getting the engine set up.
If the engine will run correctly when the model's on the ground or when the engine's on a test stand, the engine doesn't have a problem. The problem is in the engine/airframe/fuel system combination, and something's changing in the air if your engine has problems only then.
What prop and RPM are you running?
A one-way valve between the muffler and the tank usually makes running worse. You need to allow the tank to depressurize when you come off the throttle or you'll never get your idle mixture set correctly.
Is the fuel tank in the right position? The centerline of the tank should be at the same level as the center of the carburetor or no more than 3/8" lower. A too-low or too-high tank can cause problems getting the engine set up.
If the engine will run correctly when the model's on the ground or when the engine's on a test stand, the engine doesn't have a problem. The problem is in the engine/airframe/fuel system combination, and something's changing in the air if your engine has problems only then.
03-09-2011, 05:26 PM
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RE: 95 AX run in problems.
I finnaly tried a glow plug with an idle bar after nothing else worked and have not had a dead stick landing in two weeks and 8 flights sence switching to the idle bar plug (fox) I'm useing 15% cool power.13-8 master airscrew prop on an F4 phantom II from Great planes kits.
03-10-2011, 04:01 PM
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RE: 95 AX run in problems.
Hi Bax,
I know it might be difficult for you to answer this, but are you seeing more than the usual share of issues with these 95AX engines? All of my OS engines over the years have been great performers but this one was a bad egg from the start. I thought I was alone until I read this thread and head of others at my local club with similar issues.
Was there perhaps a bad batch or is the engine design just more tempermental?
I know it might be difficult for you to answer this, but are you seeing more than the usual share of issues with these 95AX engines? All of my OS engines over the years have been great performers but this one was a bad egg from the start. I thought I was alone until I read this thread and head of others at my local club with similar issues.
Was there perhaps a bad batch or is the engine design just more tempermental?
03-11-2011, 06:57 AM
#17
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RE: 95 AX run in problems.
We don't know of any issues in the O.S. Max .95 AX, itself. Every difficulty we've seen has originated external to the engine. Yes, you have to make sure you have good fuel pressure to the engine. Many aftermarket exhaust systems are useless when it comes to providing pressure to the fuel tank. That's the main problem we've seen.
06-15-2011, 07:58 AM
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RE: 95 AX run in problems.
Hey guys,..I have the same problem with my OS 95AX. Runs great at half throttle and idel but shuts off at half. Piping has been replaced and fuel tank is at center with carb and not to far in distance from carb either. I realized that if I left the igniter on,..it would run for ever on half throttle. When I took it off it would sputter and shut off. Has any one figured this out yet. Do I need a hotter glow plug. I have read that maybe the A3 or F plugs. But does the F plug fit in the head WITHOUT TOUCHING the cylinder head. Which would work. Very frustrated right now. PLEASE HELP ! ! !
06-16-2011, 06:01 AM
#19
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RE: 95 AX run in problems.
First off, you have to set the engine while it's at full throttle. Your post says nothing about full-throttle operation. Proper setting is done by first making the idle mixture very, very rich. Start the engine at part throttle and get it to full throttle after starting. Adjust the high-speed needle for proper full-throttle operation. Once it will run "all day" with no change in the needle setting, you can retard the throttle and work on getting the idle mixture found. You have to balance idle RPM with the idle mixture to get a good idle and good transition.
If the engine will not accelerate when the throttle is opened, the needles cannot be set correctly. You must have a good glow plug, of course. Make sure your fuel is clean and fresh.
If the engine will not accelerate when the throttle is opened, the needles cannot be set correctly. You must have a good glow plug, of course. Make sure your fuel is clean and fresh.
06-16-2011, 06:44 AM
#20
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RE: 95 AX run in problems.
Yes I did forget to mention that the engine works great at idle and full throttle with great transition. I also have tried new fresh fuel. I use 15% nitro fuel. But once you bring it to half throttle, it sputters and shuts off. It will run all day with the glow plug on, even at half throtle, but shuts off once you take the glow plug off. I have tried different glow plugs #8, A3, and F plug with no result. The engine has been broken in by a friend of mine at the hobby store. He has over 20 years experience with Os engines and has never seen anything like this. He is calling OS today. I may have to send this one back. Hopefully OS will have some answers for us regarding this mystery. It also seems that I am not the only one with this problem with the OS 95AX as others have stated this problem here in the forum. I just hoped that someone had found and answer to this already.
06-20-2011, 06:06 AM
#21
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RE: 95 AX run in problems.
You may need to lean the idle mixture a bit and then raise the idle RPM a bit. Many times, you can get a very, very low idleeven with a good throttle transition, but still be too rich in the midrange. That's because you have the idle RPM too low. You have to balance idle RPM and throttle transition with the high-end and midrange. Any idle lower than 2,500 RPM is good.
06-20-2011, 08:07 AM
#22
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RE: 95 AX run in problems.
This is for all OS MAX95AX USERS,
THANKS BAX for your reply,
I do have some news. It seems that I may have fixed the problem. I think there were two problems involved here. FIRST of all, I think my fuel tubing was way to long. I had two long fuel lines. One from the tank to a fuel valve, and the other one from the fuel valve to the carb. Both lines were too long. I Eliminated the fuel valve and went straight from the tank to the carb with a much shorter fuel line. After I did this the problem seemed to lessen considerably, but **** off at half throttle problem did not completely go away. So SECOND, I decided to try what others have had work for them. I changed the glow plug from a #8 to a F plug. The second I did this. she never shut off again. Not at half throttle, not at full throttle, not at idle. I have run at least a half a tank and she is running perfectly. I will take her up tomorrow and that will be the test flight. So,..in conclusion, Shortening the fuel line and changing the plug to a #8 seems to have fixed the problem. This came at the expense of bypassing the fuel valve which allows me to fuel without having an extra fill line hanging from the bottom of the plane,..but I will live with it if it was needed for the engine to work properly
THANKS BAX for your reply,
I do have some news. It seems that I may have fixed the problem. I think there were two problems involved here. FIRST of all, I think my fuel tubing was way to long. I had two long fuel lines. One from the tank to a fuel valve, and the other one from the fuel valve to the carb. Both lines were too long. I Eliminated the fuel valve and went straight from the tank to the carb with a much shorter fuel line. After I did this the problem seemed to lessen considerably, but **** off at half throttle problem did not completely go away. So SECOND, I decided to try what others have had work for them. I changed the glow plug from a #8 to a F plug. The second I did this. she never shut off again. Not at half throttle, not at full throttle, not at idle. I have run at least a half a tank and she is running perfectly. I will take her up tomorrow and that will be the test flight. So,..in conclusion, Shortening the fuel line and changing the plug to a #8 seems to have fixed the problem. This came at the expense of bypassing the fuel valve which allows me to fuel without having an extra fill line hanging from the bottom of the plane,..but I will live with it if it was needed for the engine to work properly
09-03-2011, 08:33 PM
#23
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RE: 95 AX run in problems.
I am breaking in a os 95ax i had trouble with getting it past 1/2 throttle, now today i ran a 2nd tank through it, I was able to get it full throttle by removeing my extra fuel line for filling it up. i have it in a Escapaede .61
im runninng a 15x8 ma prop, with 15% omega and a os #8. Im only getting 9800 rpm it sputters alot at full throttle. would it help to use a smaller prop if so what size?
09-26-2011, 05:30 AM
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RE: 95 AX run in problems.
I have had similar issues with my O.S. 95. I've always flown O.S. engines without any issues but this one has me stumped. It's installed in a sundowner 50. I followed the break in procedures to the letter. It runs great for the first 2 to 4 minutes then without warning just dies. I've tried several glow plug, new tubing, removing the cowl, and new fuel. Nothing seems to get this pig to run right. I'll try an F plug sometime this week weather permitting.