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Nov 04, 2017, 09:46 AM
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Thread OP
Help!

Can't start Kyosho GX-40


Hi guys!,

today I have tried to start my new kyosho GX-40 Engine (2 Stroke glow engine) and I failed... BTW. This is my first glow engine

Engine is mounted upside down, fuel is 5% nitro, glow plug is OS #8.

I filled up the tank with fuel (I had with this a problem because when I was filling it up the fuel with plane inverted through third line it went to muffler. But I realized that I need to turn the plane as it should be with engine inverted and I was able to fill the tank completly. First success. But then I tried to turn on the engine... I was trying to start it with engine inverted and I didnt make it. I was spinning the prop with chicken stick but nothing happend.

When I was driving home I was thinking about the position of engine. Should I try to start the engine in right position (with plane inverted) so the fuel which is sucked to carb is actually going on piston. Am I right or it doesnt matter at all?

thanks for any advice
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Nov 04, 2017, 10:08 AM
Mumbling in the corner.
flyboy2610's Avatar
You probably need to choke the engine to get fuel to the carburetor. Place one finger over the opening of the carburetor and , WITHOUT THE GLOW PLUG HOOKED UP, flip the propeller over rapidly several time until you see fuel in the line leading to the carburetor. Now hook up the glow plug and try to start it. This all assumes you have the needle settings correct. Using an electric starter spins the engine fast enough it doesn't have to be choked.
Nov 04, 2017, 11:09 AM
Registered User
Thread OP
Thanks for reply but i did this prior starting
Nov 04, 2017, 11:45 AM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by valdor
Hi guys!,

today I have tried to start my new kyosho GX-40 Engine (2 Stroke glow engine) and I failed... BTW. This is my first glow engine

Engine is mounted upside down, fuel is 5% nitro, glow plug is OS #8.

I filled up the tank with fuel (I had with this a problem because when I was filling it up the fuel with plane inverted through third line it went to muffler. But I realized that I need to turn the plane as it should be with engine inverted and I was able to fill the tank completly. First success. But then I tried to turn on the engine... I was trying to start it with engine inverted and I didnt make it. I was spinning the prop with chicken stick but nothing happend.

When I was driving home I was thinking about the position of engine. Should I try to start the engine in right position (with plane inverted) so the fuel which is sucked to carb is actually going on piston. Am I right or it doesnt matter at all?

thanks for any advice
Normally starting an inverted engine should not present a real problem. That is assuming you have done everything properly.

However from what I can envision from your post you may have flooded the engine when the muffler was filled with fuel. I would suggest flipping the plane over, getting the engine started, tune the engine to make sure you are familiar with the starting and running process then you can start the engine inverted.

Trouble shooting is to start with the very basic and isolate the issues one at a time.
Nov 04, 2017, 12:12 PM
Registered User
Thread OP
If i tank fuel into tank with model in normal position so i did it today and then flip over the plane the fuel will not run to muffler (Since the tube in fuel tank will be at bottom with plane inverted )?

I need to order new glow plugs...
Nov 04, 2017, 12:25 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by valdor
If i tank fuel into tank with model in normal position so i did it today and then flip over the plane the fuel will not run to muffler (Since the tube in fuel tank will be at bottom with plane inverted )?

I need to order new glow plugs...
Take the engine off from the plane. Put it on a sturdy engine test stand. Start the engine properly. Learn to work with the engine. Learn the engine behavior. Tune the engine. When engine is working properly then put it back in the airplane.

I have been flying RC for 50 years. I am still doing exactly as I have described above. There are so many things going on with an RC airplane. You will never know what cause an issue if you do not isolate the problem one at a time.
Nov 04, 2017, 12:57 PM
Registered User
Thread OP
Quote:
Originally Posted by SeismicCWave
Normally starting an inverted engine should not present a real problem. That is assuming you have done everything properly.

However from what I can envision from your post you may have flooded the engine when the muffler was filled with fuel. I would suggest flipping the plane over, getting the engine started, tune the engine to make sure you are familiar with the starting and running process then you can start the engine inverted.

Trouble shooting is to start with the very basic and isolate the issues one at a time.

If I have flooded engine then after removing glow plug from engine fuel should leak out of piston sleeve right? But no fuel was coming out of it. I have noticed that with engine inverted when I was turning the prop with chicken stick the fuel was coming out of carb. Is it normal ?
Nov 04, 2017, 01:05 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by valdor
If I have flooded engine then after removing glow plug from engine fuel should leak out of piston sleeve right? But no fuel was coming out of it. I have noticed that with engine inverted when I was turning the prop with chicken stick the fuel was coming out of carb. Is it normal ?
Yes and no. Yes if you flooded an engine in the combustion chamber you will have fuel coming out when you remove the glow plug inverted. How ever there may be raw fuel inside the crank case and with enough are fuel it can run out of your carburetor when inverted.

Also fuel coming out of the carburetor may mean you are NOT getting fuel into the engine or your carburetor has issues. Close both high speed and low speed needle gently. Then open both needles to the recommended range per your instruction manual. Fuel start the engine up right instead of inverted.

Learn the behavior of the engine.

Let me say it one more time. If you are not familiar with the function of the engine it will save you the engine and a LOT of time if you simply remove the engine and put it on a test stand. Learn to run the engine on the test stand when everything is correctly installed. Then you don't have to deal with fuel running out of the carburetor, fuel tank in the wrong position, etc. etc.

This is a hobby, learning how the engine behave is fun and part of the learning curve. Enjoy it.
Nov 04, 2017, 01:33 PM
Closed Account
Yup....

I can only agree with the test stand thing to learn your engines behaviour, or alternative, if you do not want to build a teststand, as a minimum do the first engine starts with the plane inverted and the engine right side up.

If the engine is new, it is usually going to resist starting a bit more than once it is broken in, and you being new to engines, why make it harder on yourself?

The trick with flipstarting an engine (any engine regardless of make, size or type) is to get the cylinder primed with the correct amount of fuel: after all, when flipstarting, it has to fire on that single flip, so everything must be right, or it won't fire.

How you get that correct amount of fuel in the cylinder, is different for each engine (sometimes even two identical engines prefer different priming) and it also changes when inverting the engine. What works on the teststand, does not necessarily work once the engine is inverted in the plane.
But at least, after testing on the teststand, you have learned what the engine wants, and you will quickly learn how to compensate for the inverted position.

Having said all that: you will really do yourself a favour buying an electric starter.
Nov 04, 2017, 01:50 PM
Registered User
Thread OP
Thank you both of you for your time. First thing to do is to buy an electric starter. I have a question. If I will try to run engine in right position then the vent line to muffler will be at the bottom of the tank so it will not work like it should am I right?
Nov 04, 2017, 03:42 PM
Closed Account
It is not a real problem that the vent line goes to the bottom of the tank: As long as the engine is running, it pulls fuel, so gas will bubble in the tank, instead of fuel flowing to the muffler....
There will theoretically be an extremely minor change in mixture compared to upright, but this change is so small that I very much doubt even very experienced modellers will notice it.

It is no different than flying inverted, and your plane most definitely can fly inverted....
Nov 04, 2017, 05:46 PM
AMA 46133
SeismicCWave's Avatar
Quote:
Originally Posted by valdor
Thank you both of you for your time. First thing to do is to buy an electric starter. I have a question. If I will try to run engine in right position then the vent line to muffler will be at the bottom of the tank so it will not work like it should am I right?
As long as there is no fuel coming out of the vent line. One fuel starts to come out it will continue to siphon the rest of the fuel and keep on dripping.

That's why I strongly advocate a test stand with the fuel tank mounted properly so you can get rid of all the variables coming from the air frame.
Nov 05, 2017, 09:55 AM
Registered User
A Sullivan 90 size electric starter, and a 12 volt battery (Ace Hardware, the camping isle) would be a good investment. Trying to hand flip an engine, when you don't know if the screws are tuned right, can lead to hours of flipping. You'll get abs on your flipping arm!

Make sure that your glow lighter lights up the glow plug (take it out, and check this).
Good luck.
Nov 05, 2017, 10:42 AM
Registered User
Cougar429's Avatar
Valdor, a few things that can possibly affecting your engine.

First, even with 30 years experience, I found inverted a problematic installation and not one I would recommend for your first exposure to nitro. There are the issues of tank height,(most installations I encounter do not accurately place the tank for this orientation) plug wash and even "Hydrolock" are more critical with the engine anywhere beyond 90 degree side mount.

I would have to ask what your environmental conditions are when trying to get it to fire off. The OS #8 is a general purpose plug, (and perfectly suited for this engine) but it may not be best for your conditions or mounting.

I normally switch to the hotter #3 when the temps drop below 40F as the #8 could cool off too much to keep a reliable idle even with engines mounted upright or side. With inverted the wash of fuel/lube, even at optimal mixtures, could overcool any 2-stroke plug, so I found the use of a 4-stroke plug such as the OS "F" or "R" the best option. These are built to retain enough heat through the 3 non-power strokes of that type engine to fire the next cycle.

Never had nor needed the chance to work with an idle bar plug. Some have reported success as that too can keep the filament from overexposure.

On that subject, take a good look at the plug filament. If any deformity or damage it could be too compromised to work.

You seem to have the concept of tank orientation already in mind. However, you want to have it set so that the level of fuel at half tank is even with the carb inlet fitting.

Quote:
I have noticed that with engine inverted when I was turning the prop with chicken stick the fuel was coming out of carb. Is it normal ?
This will be the case with the engine inverted since upright will have any fuel that makes it into the carb drop into the crank and from there to the case center to be pushed into the chamber next time the piston drops. Inverted would mean that fuel tends to migrate the other way, out the carb inlet and from there to the ground. Flipping by hand will possibly not create enough pull into the case to draw in the fuel. If you have access to the carb then plugging the inlet with your finger while turning the prop could draw in enough to fully wet the carb and reach the crank bore. This is where experience may count as you could tell when the engine is wet enough to fire.

NOTE: I would STRONGLY recommend doing any priming with the glow heat off. I have seen and had engines fire and kick back quite energetically and if not wearing a glove or using a stick would have likely meant injury. NEVER apply heat till fully ready to fire it up.

On the note of electric starting, you come to my final point of "Hydrolock". Inverting the cylinder can have a slug of fuel/oil enter the chamber and have no exit once the piston closes the ports. Liquid cannot compress so forcing the piston higher in the chamber can mechanically overstress the engine. Blowing off the head, bending or breaking the rod or crank or damaging the bearings are possibilities here. Damage may not be immediately apparent, but can come back to bite later. Damage to the plug filament I mentioned earlier is another minor issue.

This is why you see in films of radial engined aircraft of WWII vintage ground crews manually walking prop blades through. This could tell if the conditions were there and/or clear them out before hitting them with the starter. In those situations aircraft availability was critical so time and effort were spent there.


Electric starting will mean you could cause this damage before you have the chance to realize the conditions are there. This is why I teach my students to always flip engines by hand, (with glow heat removed) at least several times before applying external power.

Having said all that, the problems can be overcome, just not something I would want to try with little or no experience. Also, as mentioned before, new engines are finicky to begin with, usually requiring a bit richer mixture to keep running. Each manufacturer usually lists a break in procedure and I would follow it.

Also, you will find this is hard on glow plugs. Microscopic bits wear off as everything fits together and with a 2-stroke all that goes directly through the combustion chamber. This can impinge on the filament and compromise the catalytic action that keeps the plug hot enough to fire when heat removed. You may find the engine impossible to keep running or fire off at all and only a new plug will fix it. This is why I try to use old plugs when I fire up any engine that is new, rebuilt or stored for long term. Only switch to new when break in is complete.
Last edited by Cougar429; Nov 05, 2017 at 10:52 AM.
Nov 05, 2017, 11:59 AM
Registered User
Thread OP
Thank you Cougar for sharing your experience with me. The only option is to leave the engine inverted in this airplane. I have ordered an electric starter and 2 glow plugs rated as "hot" from MP Jet. I live in Poland, Europe so nowadays the weather is rather cold so maybe I just didnt had a chance to hand start this engine.. When it will be a little bit warmer I will try to fill the tank with airplane upright position, prime the engine with plugging the inlet with finger and spin the prop a little more so it will drain more fuel into crank bore and then try to start the engine with electric starter with throttle at 30-50%. Does it sound okay?

I have another question about powering up glow plug since I have a panel starter with adjustable Amps for glow plug. What I should look for to heat the glow plug right and not to burn it down at the same time?

ps. I have burnt 2 glow plugs ... my bad


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