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Nov 05, 2009, 01:08 PM
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pryor808's Avatar
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Inverted 2 stroke engine start


I understand that mounting a stroke engine inverted is not an issue but, just as long as the fuel tank is level or slightly below the carb (spray bar). The starting procedure will require turning the prop a couple of times to eliminate any fuel sitting in the bottom of the cylinder head. Starting an engine with fuel pooled up in the cylinder head can cause hydrolock catastrophy. My question! The turning (priming) procedure of the engine, I imagine that this is done without the glow igniter on the glow plug and, if so! where does the fuel that is pooled up in the cylinder head go by turning the prop a couple of times? The reason I am confused is due to the exhaust port is now above the pooled fuel and, the only thing I can think of is the fuel being burned off or drained by removing the glow plug?
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Nov 05, 2009, 01:45 PM
If it's so flooded that you can't turn the engine over, turn the whole airplane upside down so the engine is right side up. Flip the engine a few times to clear the flood, then turn pane right side up and start engine.

You can remove the plug but that's the hard way.
Nov 05, 2009, 03:00 PM
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Originally Posted by glowguy47
If it's so flooded that you can't turn the engine over, turn the whole airplane upside down so the engine is right side up. Flip the engine a few times to clear the flood, then turn pane right side up and start engine.

You can remove the plug but that's the hard way.
Glowboy! The question is, where does the fuel go by turning the prop of couple of times? being inverted!
Nov 05, 2009, 09:19 PM
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Actually turning the prop over a few times is simply to ensure you don't have a flooded engine, it can't clear any excess fuel. If the compression feels higher than normal then it's still flooded but not to the point of hydraulic lock and still needs to be cleared. If you want to clear it by turning the entire model then do it in a direction where it can run straight out of the exhaust into the muffler otherwise it'll run back through the transfer ports into the crankcase. Personally I prefer to remove the plug and flick/spin the engine over a few times and then blow any fuel out of the plug itself.
Nov 05, 2009, 09:39 PM
Quote:
Originally Posted by pryor808
Glowboy! The question is, where does the fuel go by turning the prop of couple of times? being inverted!
Obviously it doesn't go anywhere if the engine has a hydraulic lock. If it is hydraulically locked you CAN'T turn the engine over and the fuel stays right there in the cylinder head. Like downunder said if it's still flooded but NOT locked you can turn it. Otherwise you have to either take out the plug or turn the engine right side up. It's easy to just turn the engine right side up. IMHO.
Nov 06, 2009, 03:31 AM
Bombs away! Err...landing
Ira NZ's Avatar
Quote:
Originally Posted by pryor808
I understand that mounting a stroke engine inverted is not an issue but, just as long as the fuel tank is level or slightly below the carb (spray bar). The starting procedure will require turning the prop a couple of times to eliminate any fuel sitting in the bottom of the cylinder head. Starting an engine with fuel pooled up in the cylinder head can cause hydrolock catastrophy. My question! The turning (priming) procedure of the engine, I imagine that this is done without the glow igniter on the glow plug and, if so! where does the fuel that is pooled up in the cylinder head go by turning the prop a couple of times? The reason I am confused is due to the exhaust port is now above the pooled fuel and, the only thing I can think of is the fuel being burned off or drained by removing the glow plug?
I don't quite get how people can hydrolock an engine because it's inverted. My problem is always getting the fuel INTO the engine because it goes straight out of the carb onto the ground, even if you have heaps of fuel siphoning from the tank.
Nov 06, 2009, 06:48 AM
I am ready for HHAEFI!!
powerlines's Avatar
What I have done in the past with inverted engines... Put finger over muffler and flip 3-4 times to prime then attach Glo and bump backwards.. You don't wan't to over prime it.. It will flood easy.. then you will never get it started.

Try that and let me know the results....

PS.. I always ran Satio 4 Strokes.. Now.. I am all electric and one Gasser..
Nov 06, 2009, 06:51 AM
I am ready for HHAEFI!!
powerlines's Avatar
AND to answer your question.. the pool of fuel. goes to the top of the head where the glo plug is.. that is why it won't start. can't burn and get hot enough.. I have had guys come to the field and could do nothing to crank motor.. Starters and all.. I would walk over.. get them to hold plane inverted. flip a few times to clear motor.. apply glo and bump backwards and WHAM!!
Nov 06, 2009, 10:24 PM
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Quote:
Originally Posted by downunder
Actually turning the prop over a few times is simply to ensure you don't have a flooded engine, it can't clear any excess fuel. If the compression feels higher than normal then it's still flooded but not to the point of hydraulic lock and still needs to be cleared. If you want to clear it by turning the entire model then do it in a direction where it can run straight out of the exhaust into the muffler otherwise it'll run back through the transfer ports into the crankcase. Personally I prefer to remove the plug and flick/spin the engine over a few times and then blow any fuel out of the plug itself.
Thanks for the clarification. I feel confortable in installing my engine inverted now. I really did not have a choice but, at least now I know what I am doing.


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