Four Stroke starting problems
07-30-2004 | 12:22 PM
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From: ijmuiden, NETHERLANDS
Four Stroke starting problems
Hello,
I bought a ASP FS120AR. and now i'm trying to get it running(I got it running but it was/is very difficult[&o]).
The first problem is that it looks that it has very little compression, a second problem is that it looks like it is blowing back fuel fuel into the tank.
Has anyone a solution for these problems[8D]?
greetings
Robert Heuveling
I bought a ASP FS120AR. and now i'm trying to get it running(I got it running but it was/is very difficult[&o]).
The first problem is that it looks that it has very little compression, a second problem is that it looks like it is blowing back fuel fuel into the tank.
Has anyone a solution for these problems[8D]?
greetings
Robert Heuveling
07-30-2004 | 12:45 PM
#2
RE: Four Stroke starting problems
This is a new engine, right?
Then compression should/will get better when you get some time on the engine. It needs to run in.
Do you mean it is blowing back black fuel into the tank? That is not uncommon either, especially if you are using castor based fuels.
Also the black stuff indicates that the engine is running in. It is metal shavings from inside your engine mixed with oil. The oil is supposed to carry the metal particles out of the engine.
How are you starting it? Are you using a starter, or your hands?
Try this: Choke the engine until it is good and wet (no glow current please). After you get it good and wet, try to turn it over by hand to see if it is not hydro locked because of too much fuel in the combustion chamber. If you are unable to turn it over by hand there's too much fuel in the engine. If this happens, just rock the prop back and forth against compression to clear out the excess fuel.
After you have made sure the engine is wet, but not hydro locked, switch on the glow current and give prop a good hard swing against compression, but in the "wrong" direction. That means clockwise when standing in front of your plane. The prop should bounce against compression, and the engine will start running in the right direction.
This may take some practise, but it works very well. Just make sure your finger are clear of the prop when it hits compression... or they will be sore for a while
For the first minutes, keep the engine blubbering rich and leave the glow current connected to keep it running.
After the first tank or so, GRADUALLY start leaning out the needles, so that it stays running without glow current.
Then compression should/will get better when you get some time on the engine. It needs to run in.
Do you mean it is blowing back black fuel into the tank? That is not uncommon either, especially if you are using castor based fuels.
Also the black stuff indicates that the engine is running in. It is metal shavings from inside your engine mixed with oil. The oil is supposed to carry the metal particles out of the engine.
How are you starting it? Are you using a starter, or your hands?
Try this: Choke the engine until it is good and wet (no glow current please). After you get it good and wet, try to turn it over by hand to see if it is not hydro locked because of too much fuel in the combustion chamber. If you are unable to turn it over by hand there's too much fuel in the engine. If this happens, just rock the prop back and forth against compression to clear out the excess fuel.
After you have made sure the engine is wet, but not hydro locked, switch on the glow current and give prop a good hard swing against compression, but in the "wrong" direction. That means clockwise when standing in front of your plane. The prop should bounce against compression, and the engine will start running in the right direction.
This may take some practise, but it works very well. Just make sure your finger are clear of the prop when it hits compression... or they will be sore for a while
For the first minutes, keep the engine blubbering rich and leave the glow current connected to keep it running.
After the first tank or so, GRADUALLY start leaning out the needles, so that it stays running without glow current.
07-30-2004 | 05:07 PM
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From: Houston,
TX
RE: Four Stroke starting problems
I'm new to 4 strokes, but I thought you were NOT supposed to pull too much fuel into the chamber with them. With the top side valves you'll have to make sure you are opening a valve to get the fuel out? Maybe I'm off on this, but I swear that's what I read earlier.
Duke
Duke
07-30-2004 | 07:31 PM
#4
RE: Four Stroke starting problems
You are NOT supposed to try to START the engine with too much fuel in the chamber.
Apparently it doesn't matter where the valves are... rocking the prop back and forth against compression must evaporate the excess methanol or something, because it works no matter how your engine is positioned. Granted, it goes faster on an inverted or side mounted engine.
As for not pulling too much fuel into the engine... how are you going to check that?
The only way I found to start larger four strokes easily is by getting 'em wet... that means too much fuel most of the time. When you get to know your setup you can develop a feeling about the required number of choked prop turns to get the right amount of fuel though.
Starters and four strokes don't mix very well I think, which is why I hand start mine... and trying to start a large four stroke like a .40 two stroke WILL result in sore fingers or nicked props when you use a chicken stick... which is why the "back-flip" works better... and back flipping requires a wet engine... can't have it all...
Apparently it doesn't matter where the valves are... rocking the prop back and forth against compression must evaporate the excess methanol or something, because it works no matter how your engine is positioned. Granted, it goes faster on an inverted or side mounted engine.
As for not pulling too much fuel into the engine... how are you going to check that?
The only way I found to start larger four strokes easily is by getting 'em wet... that means too much fuel most of the time. When you get to know your setup you can develop a feeling about the required number of choked prop turns to get the right amount of fuel though.
Starters and four strokes don't mix very well I think, which is why I hand start mine... and trying to start a large four stroke like a .40 two stroke WILL result in sore fingers or nicked props when you use a chicken stick... which is why the "back-flip" works better... and back flipping requires a wet engine... can't have it all...
07-31-2004 | 05:27 PM
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From: Northampton, UNITED KINGDOM
RE: Four Stroke starting problems
Robert,
The symptoms, as you describe them, sound very much like the valve timing is incorrect.
There could be many other reasons of course, but if all the obvious ckecks fail check the valves.
Mick.
The symptoms, as you describe them, sound very much like the valve timing is incorrect.
There could be many other reasons of course, but if all the obvious ckecks fail check the valves.
Mick.
08-02-2004 | 06:14 AM
#8
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RE: Four Stroke starting problems
Regardless of which brand you buy, ALWAYS check the valve adjustments prior to first running it then again after about the first hour of running as they will wear and change settings. After initial breaking, you should check the valve settings at least once for every season of flying. I have no trouble starting mine with a starter. However I always remove the mechanical choke and do not choke on start up. Just turning it over with the starter draws plenty of fuel to get things going.
