Mounting inverted
05-11-2005 | 07:46 AM
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From: Birmingham,
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Mounting inverted
Is there anything special you need to do in order to run an engine inverted? I have an old OS .25 FP that runs pretty good right side up, but doesn't seem to want to run (or even start) when mounted upside down.
05-11-2005 | 10:56 AM
#2
RE: Mounting inverted
An upright engine is more tolerant of an overprime and idle mix settings. With an inverted engine you have to learn how to get fuel to flow uphill from the spray bar and through the crankshaft port. But also you can't overdo how much you prime or you can get a hydraulic lock which could cause serious damage. With the idle mix you need to set it more carefully to where it's just barely on the rich side. Once you figure out the priming they'll start one flick just as easily as upright. If you must use an electric starter it's wise to flick it over by hand 5 or 6 times after priming to make sure it's not flooded. If you do this then always treat it as though the glow heater is working because one day it will be 
05-11-2005 | 08:17 PM
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From: RCHill,
NJ
RE: Mounting inverted
I recently broke in a mag .28 a little more than 1/4 inverted. The things I found useful to do are:
1. prime engine inverted but before moving finger flip the engine up right to get the fuel into the shaft. If you don't you will see the fuel dripping from the carb.
2. when refueling don't turn the engine up right, the fuel will fill the muffler quicker than a thief leaving a bank after a stick up.
3.make sure once you have the engine running it is running counter clock wise. I have never had an engine run clock wise until this inverted mess was done.
4. try different plugs , no explanation except when I switch from an OS A3 to an OS 8 the engine ran better.
5. Although inverted the up down ground test is the same .
6. good luck I hope this helps.
1. prime engine inverted but before moving finger flip the engine up right to get the fuel into the shaft. If you don't you will see the fuel dripping from the carb.
2. when refueling don't turn the engine up right, the fuel will fill the muffler quicker than a thief leaving a bank after a stick up.
3.make sure once you have the engine running it is running counter clock wise. I have never had an engine run clock wise until this inverted mess was done.
4. try different plugs , no explanation except when I switch from an OS A3 to an OS 8 the engine ran better.
5. Although inverted the up down ground test is the same .
6. good luck I hope this helps.
05-11-2005 | 10:53 PM
#5
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RE: Mounting inverted
ORIGINAL: BShin
Is there anything special you need to do in order to run an engine inverted? I
have an old OS .25 FP that runs pretty good right side up, but doesn't seem
to want to run (or even start) when mounted upside down.
Is there anything special you need to do in order to run an engine inverted? I
have an old OS .25 FP that runs pretty good right side up, but doesn't seem
to want to run (or even start) when mounted upside down.
you get it set right. Keep in mind, with the carb down so low under the tank
flooding can happen, and even fuel siphoning. Is is harder to hand prime the
engine....as has been noted here.
The best way I have found to start in inverted engine is to fuel it, hook up the
glow, put your finger over the exhaust outlet, and hit it for one second with
the electric starter....the engine will start almost instantly.
FBD.
05-12-2005 | 06:35 AM
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RE: Mounting inverted
Thanks for all the info guys....I've experienced all of the situations mentioned and think I'm finally getting there.
I'm putting the engine on a little .25 size Ultimate 30 Bipe I found on the internet. Neat little plane, but it was made in China and the instructions had about four lines of written instructions (literally), and non descript drawings instead of pictures...so it's been interesting putting it together since it's my first bipe. It's an ARF and nicely made but the lack of instructions has caused me to make a few mistakes.
Anyway, my first test run was on my field stand without the wings. I tried to fuel it with the engine upright (which put the plane upside down), and man, did the fuel come flying out of the muffler. I forgot all about the tank being upside down (duh). I took the engine off the plane and mounted it on my test stand and tried to run it upside down there. Kept flooding the carb and locking the shaft up, only to realize I had the fuel tank about 6 inches above the carb. FINALLY, I repositioned the tank to about level, if not slightly lower than the carb, only gave it about one flip for priming, and voila, it cranked. I'm not sure if I'm detecting a very slight mist of fuel in the air behind the prop, and if so, if this is caused by it being inverted. I guess I can live with that as long as it flies. I'll be checking the inside of the cowling to see if it makes a big mess.
I'll be trying some of your other suggestions, but wanted to say again, thanks for your help....
Brian
I'm putting the engine on a little .25 size Ultimate 30 Bipe I found on the internet. Neat little plane, but it was made in China and the instructions had about four lines of written instructions (literally), and non descript drawings instead of pictures...so it's been interesting putting it together since it's my first bipe. It's an ARF and nicely made but the lack of instructions has caused me to make a few mistakes.
Anyway, my first test run was on my field stand without the wings. I tried to fuel it with the engine upright (which put the plane upside down), and man, did the fuel come flying out of the muffler. I forgot all about the tank being upside down (duh). I took the engine off the plane and mounted it on my test stand and tried to run it upside down there. Kept flooding the carb and locking the shaft up, only to realize I had the fuel tank about 6 inches above the carb. FINALLY, I repositioned the tank to about level, if not slightly lower than the carb, only gave it about one flip for priming, and voila, it cranked. I'm not sure if I'm detecting a very slight mist of fuel in the air behind the prop, and if so, if this is caused by it being inverted. I guess I can live with that as long as it flies. I'll be checking the inside of the cowling to see if it makes a big mess.
I'll be trying some of your other suggestions, but wanted to say again, thanks for your help....
Brian
05-12-2005 | 01:35 PM
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From: Mary Esther, Florida, FL
RE: Mounting inverted
Brian:
The fuel mist out of the carb is normal. The port timing is syuch that there is a reversed air flow at certain engine speeds, this blows raw fuel out. See [link=http://www.rcuniverse.com/forum/Saito_Velocity_Stack_and_O%2DRings/m_2946848/tm.htm]this thread[/link] for a discussion of stacks on the inake to capture the fuel that would otherwise be lost.
The engines discussed are primarily Saito, but there's some two stroke stuff there also. Including a picture of a stack I put on a Magnum 0.25, almost the same engine you have.
Bill.
The fuel mist out of the carb is normal. The port timing is syuch that there is a reversed air flow at certain engine speeds, this blows raw fuel out. See [link=http://www.rcuniverse.com/forum/Saito_Velocity_Stack_and_O%2DRings/m_2946848/tm.htm]this thread[/link] for a discussion of stacks on the inake to capture the fuel that would otherwise be lost.
The engines discussed are primarily Saito, but there's some two stroke stuff there also. Including a picture of a stack I put on a Magnum 0.25, almost the same engine you have.
Bill.
05-12-2005 | 01:36 PM
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From: Mary Esther, Florida, FL
RE: Mounting inverted
Brian:
The fuel mist out of the carb is normal. The port timing is syuch that there is a reversed air flow at certain engine speeds, this blows raw fuel out. See [link=http://www.rcuniverse.com/forum/Saito_Velocity_Stack_and_O%2DRings/m_2946848/tm.htm]this thread[/link] for a discussion of stacks on the inake to capture the fuel that would otherwise be lost.
The engines discussed are primarily Saito, but there's some two stroke stuff there also. Including a picture of a stack I put on a Magnum 0.25, almost the same engine you have.
Bill.
The fuel mist out of the carb is normal. The port timing is syuch that there is a reversed air flow at certain engine speeds, this blows raw fuel out. See [link=http://www.rcuniverse.com/forum/Saito_Velocity_Stack_and_O%2DRings/m_2946848/tm.htm]this thread[/link] for a discussion of stacks on the inake to capture the fuel that would otherwise be lost.
The engines discussed are primarily Saito, but there's some two stroke stuff there also. Including a picture of a stack I put on a Magnum 0.25, almost the same engine you have.
Bill.
