Hi..Iv have started having my own piper j-3 plane setup few weeks back.all the linkages has been assembled.But i have problm actually trying to start my engine.How do you start a gas engine on a plane.Im using a .25 2stroke irvine engine and it is fixed inverted at the front of the plabe.
the carb is facing down.when the fuel goes into the carb it will spill out.so how do you get the engine running?how do i turn the propeller and get the engine running?? many thanks.

In short:
To run, the engine need: Air, fuel and a glowing plug to set it off.


1. Open carb to full throttle, cover the air intake of the carb with your thumb and spin prob.
This is done to prime the engine, the goal is to get some fuel into the cylinder.

2. Close carb to idle, make sure you have the linkages correct so when idle, there should be a small slit open in the carb.

3. Apply power to glow plug

4. Hold the plane firmly, or teather it to something

5. Spin prop to fire the engine

6. Remove power from glow plug

hey thanks! but how do i stop the fuel from coming out from the carb? my engine placement is inverted?

my inverted engine irvine.25

When you spin the prop and keep open throttle there will pass fuel into the cylinder.
If in doubt, put the plane inverted on a plane stand and start the engine with the carb pointing up

You can also remove the glow plug and pour (very little) fuel directly in the cylinder.
Just be careful, there's something called hydrolock. This is when you have to much fuel in the cylinde and the piston can't move freely.
If you then force the piston you can break the engine.
It should be tight, but if it's almost impossible you have to much fuel in the cylinder end need to empty it. Remove glow plug and spin prop to vent out the extra fuel.

Make sure that when you prime the engine (full throttle, thumb over air intake, spinning the prop) there's fuel sucked up through the fuel lines.
When the fuel reaches the carb, you shold spin the prop 3-4 times by using the "prime" technique, then you're ready to close air intake to idle and connect the power to the glow plug.

Make sure the glow plug works by removing it from the cylinder and testing it with your power source.
The coil in the plug should glow bright orange.

Watch your fingers and ALWAYS make sure you have the air intake in idle position before attaching glow power and starting the engine.
If you forget the throttle at full power and you start the engine you might panic and put your fingers in the propellor, or the plane jumps up and bite you... just be careful. it's not a toy!

I've never had to do this on anything other than a Cox .049 engine. Even with that, there was no need to remove the glow plug.

Piperofna, most of what test005 has told you will work, but I have a different perspective. Since you have questions about running the engine, it sounds like you are a beginner. What are your plans for flying the plane? Have you arranged someone to help you learn? If you have, I suggest that you wait until you are with this person before you try to start the engine. They should know how to get it running and how to tune it. They will also be able to show you basic safety information to help you avoid getting hurt.

hI thanks for the reply.Yes i am a beginner into gas planes.BUt currently I am still running my nitro car..its been with me for a couple of years.I fly the estarter before but jus trying my hands on gas planes.I wanted to give up buildeing the plane before this but its now done up and im determine to get this plane up.Jus wondering how you guys start the gas engine. SO INDEED the plane had to be inverted.that makes sense alright.

One more question are the aileron flaps suppose to elavate up jus abit ??...as i notice my rudder and elevator seems to flap quite well.

Dude, 2 words......... GET HELP!

You stand a very high chance of hurting yourself, cutting off a finger or hurting someone else. If you get it in the air by some chance, you will crash it within 30 seconds.

Don't be in such a hurry. It takes less time to get help than to rebuild.

i agree with the guys for you to seek out help. a cub is not an easy plane to learn on without any help. you could easily break something just on the squirrelly take off run. get help!!! oh yeah... and getting a finger chopped up or worse, off, is definitely a good way to ensure you exit the hobby early.

as for the spilling out of fuel. this is likely because the level of your carb is significantly lower than the level of your tank. so what is happening is gravity is pulling out the fuel once you've primed it to start your engine. you've got to lower your tank so that the middle of the tank is about the level of the carb, otherwise you will always be flooding the carb. this is why having your engine side mounted is always safer than inverted.

Piperofna beat me to it...lower your fuel tank. If you've flown before and this is your first glow engine plane I partly agree. You should get someone to go over some tuning techniques and saftey procedures but I seriously doubt if you'll crash in 30 seconds, everyone is different, some people need more help but like I said if you've flown before then you should be fine with a cub, except taking off will be scarey (keep everyone away and get some help with this-tail draggers are not stable on take off if you don't know what you are doing) but I would have an experienced flier or instructor there the first time at least. As for the ailerons they should be level. Slightly down will increase lift and slightly up will loose some lift but make them level on all flight surfaces. This does not mean you won't have to add some trim into the control surfaces though.

Sounds like you had a hard time building it and got a little frustrated once or twice. It sure is going to sting when you crash it! Get some help!

NEVER try to start a glow engine upside down, the chance of a hydralic lock bending or breaking a rod is very high. You can still flood the engine right side up too. The very best position for starting is with the engine on its' side and the exhaust port facing down. It is easier to draw fuel into the chamber and to dump excess fuel out the exhaust if there is a flood. C/L combat guys get one flip starts 90% of the time this way.

One thing that I noticed is he said fuel is pouring from the carb on an inverted setup. This is a good indication that the centerline of the fuel tank is much higher than the carb itself

Or am I reading this wrong and if so just slap me a little harder next time.

Sometimes because of the design layout of the model, ideal tank positioning is hard to get. The model builder should definitely try to get it as close as he can. The point about firing up an upside down engine, is that it only takes a couple of drops of fuel puddled in the combustion chamber to drench a glow plug. If you are trying to start an engine with a high mounted tank, tilt the nose up slightly. Likewise, if you are trying to start a set up with poor fuel draw, tilt the nose down. I think it is a good idea to keep a set of hemostats around so you can pinch the feed line if you have a system that tends to flood itself automatically.

[X(]

Can I use that one?

Sean

combatpigg - starting it with the nose raised... that's ingenius! i've never thought about that. raising the nose of the plane creates the effect of tilting your engine to one side. only thing is that it will only work with 2 stroke engines. on a four stroke, it will only worsen the situation because the glow plug is in back (other than enya engines)

never say never... I've got quite a few planes with inverted engines, NONE of which I have ever started right side up. I almost always chicken stick start them, and obviously check to make sure they aren't flooded. personally most of planes are fairly dangerous to start upsidedown, there is no good way to rest it safely in the cradle.

Well, continue to march, then. I'll have to spread the news to the scores of guys who I have flown with and to the guys who I fly with now to start doing it your way.