Mounting 2 stroke inverted: help
 

I am buying a Fliton Inspire 60 ARF. I will be doing a lot of 3D with it. This will require mounting a ST 51 inverted. I've heard stories that 2 strokes do like being inverted. What are the drawbacks to doing this? Is there anything I can do to help it run better inverted?

RE: Mounting 2 stroke inverted: help
 

Just be sure your tank centerline is 1/4 to1/2 inch below the needle valve(s).

RE: Mounting 2 stroke inverted: help
 

The main drawback is it may tend to run rich, especially at idle, and it may be hard to keep the plug lit. Use an onboard lighter and run the low end a little lean. When using an electric starter, turn the prop through a couple of times before applying it, to be sure the engine isn't hydro-locked.

Dr.1

RE: Mounting 2 stroke inverted: help
 

Any 3D plane is going to be inverted at one time or another, I wouldn't be to worried about it. Go with what DR1 said ^ an you will be fine. Don't just grab the electric starter an go to spinnin, could bend a rod. Be sure when you start it up to have someone hold it strait up while you work the throttle makeing sure you have a good clean transition. This would be the best time for it to lean out on you rather than in a tourqe roll an break the stab

RE: Mounting 2 stroke inverted: help
 

The bottom line is that the engine really doesn't care what position it is in. It will run the same in all positions. The catch is that if the spray bar of the carb is too much below the centerline of the tank when it's on the bench the fuel will siphon into the carb and thus into the engine possibly locking it or flooding it at the least.

RE: Mounting 2 stroke inverted: help
 

Are you sure you can't just mount at a downward angle so that the muffler is at the bottom of the fuselage? The engines aren't as touchy mounted like this as there are if they are inverted. [&o]

RE: Mounting 2 stroke inverted: help
 

the engine on my cloud dancer is inverted and it is a pita sometimes. I couldnt keep it running long enough to do anything. I finally had my friend hold it upsidedown, (motor right side up) and tuned it that way to get a decent starting point. If you can, lean the low end a bit it will help. It is a diffrent critter when they are upside down. Once you get it tuned right, it is just as solid as right side up. Plugs with the idle bar do not help much. I tried 3 diffrent types. So unless you want to , I wouldnt bother with that. Just go with the onboard driver.

RE: Mounting 2 stroke inverted: help
 

If you have any engine issues at all, the tank position will be the root cause of it all. I run several planes with inverted engines. All with tanks lowered. I have friend who run inverted engines who have nothing but trouble, all with tanks inthe original slots. Your choice.

RE: Mounting 2 stroke inverted: help
 

There is no substitute for learning how to tune your engine. I have had many a airplane with an inverted glow 2 stroke. Yeah, I don't like to do it any more. Why? 'Cause I know it takes work and fiddlin' to make it reliable. But it will work. Go for it man. You'll learn tons....

Raf

RE: Mounting 2 stroke inverted: help
 

I had an Evolution 100 that just would not run right upside down. I played with it for two or three months, got very frustrated with it. I changed over to an OS 1.20 AX and mounted that upside down and it ran like a champ, no problems at all. Same installation, same plane, but different engine and it was great.

I don't know much about the ST 51 you are planning on using but do know that the Evo 100 was no good in that application. It was very fussy about needle settings, idle set then HS set it would run fine at full throttle but not idle. Set the idle and it would not run good at HS. Fly it, and it would die after a few orbits. Even the club pro's could not get it to run right, and we have some real pro's in our club. As someone said above, you will definitely learn to tune an engine that way. I learned a lot with the EVO 100 that I applied to the OS 1.20 AX, and it was worth it. The plane, an Excelleron 90 pattern plane, has pretty much unlimited vertical and runs forever inverted. With the EVO 100, I was happy to get a couple orbits out of it before it started to act up. Pain in the butt.

As I said, all I did was change to the OS 1.20 AX and nothing else.. and it ran like a champ. All depends on if you know enough about the engine and can get it to run right at all settings and speeds. No one runs at full throttle all the time, so mid range is important... so the transition zone between idle and WOT is a critical area that some engines just don't tolerate well, and the EVO 100 is one of them. All I can say is try it, and get it set up right, and see if it runs ok. If not.. well, alternative engines may be an option.

DS.