OS 70 4 stroke heartache
06-17-2002, 08:55 PM
#1
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OS 70 4 stroke heartache
Help!!! I just bought a brand new OS 70 4s and I don't know if I'm doing something wrong...
The instructions say to close the needle valve and open 3 to 3 1/2 turns and then lean it out... I start it and the engine rattles so bad its hard to adjust the needle (my fingers go numb holding the needle). As I lean it out, per the instructions, the revs climb and the heavy smoke clears a bit, but if I start moving the throttle, it cuts out... What can I do.. I don't have access to guys at my club during the week...
Also, when looking at the fuel line, I can see a lot of air bubbles... Is that OK?
Any suggestions? Please..
BTW... its mounted on a profile Morris TopCap in a cool way.. in stead of mounting the engine with the bottom on the fuselage, i widened the fuse a bit and mounted the engine with the crank case on the other side of the fuse. (hard to explain)
The instructions say to close the needle valve and open 3 to 3 1/2 turns and then lean it out... I start it and the engine rattles so bad its hard to adjust the needle (my fingers go numb holding the needle). As I lean it out, per the instructions, the revs climb and the heavy smoke clears a bit, but if I start moving the throttle, it cuts out... What can I do.. I don't have access to guys at my club during the week...
Also, when looking at the fuel line, I can see a lot of air bubbles... Is that OK?
Any suggestions? Please..
BTW... its mounted on a profile Morris TopCap in a cool way.. in stead of mounting the engine with the bottom on the fuselage, i widened the fuse a bit and mounted the engine with the crank case on the other side of the fuse. (hard to explain)
06-17-2002, 11:01 PM
#2
OS 70 4 stroke heartache
Relax , You bought a very good engine and when this is all behind it will seem like nothing.
It sounds like you are leaning out before the throttle is open , you should open the throttle when the engine starts, set the needle on the rich side at about 6000 rpm,let it run a bit THEN work on the idle.
You are probably too rich at idle and when you try to lean the main (high speed ) needle you are making the engine lean at the high end. When you try to open the throttle the engine will be too lean to run. Make sure you have a well balanced prop in the recomended size range .
Try again and don't sweat it . You will have it purring in no time . Your friends won't let you down and you have the frindliest OS four stroker there.
Let us know how you do.
It sounds like you are leaning out before the throttle is open , you should open the throttle when the engine starts, set the needle on the rich side at about 6000 rpm,let it run a bit THEN work on the idle.
You are probably too rich at idle and when you try to lean the main (high speed ) needle you are making the engine lean at the high end. When you try to open the throttle the engine will be too lean to run. Make sure you have a well balanced prop in the recomended size range .
Try again and don't sweat it . You will have it purring in no time . Your friends won't let you down and you have the frindliest OS four stroker there.
Let us know how you do.
06-17-2002, 11:30 PM
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OS 70 4 stroke heartache
Traditionaly you should leave the throtle wide open and use the needle valve to control speed for the first tankful or two of fuel. open it up to slow it down and close it a little to speed it up, alternating a few moments of low speed with a few moments of high speed with more and more high speed as it comes towards being broken in. This gives it lots of oil for lubracation and cooling till it wears in. when you can lean it in for top RPM and it will hold an idle it is about ready to fly.
06-17-2002, 11:37 PM
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OS 70 4 stroke heartache
Bubbles in the fuel line would indicate an air leak in the fuel line or tank. Check the lines(internal and external) for pin holes, replace as required.
06-17-2002, 11:43 PM
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OS 70 4 stroke heartache
Air bubbles in the fuel line is not ok.
It shouldn't shake as bad as you say yours is shaking. Make sure your prop is balanced and a good break-in size prop would be a 12x6.
Adjust high speed needle with throttle wide open. Worry about the low speed needle after break-in.
It would be best to first run it on a test stand rather than your profile plane. It going to be spitting alot of oil and no need to goo up your plane.
It shouldn't shake as bad as you say yours is shaking. Make sure your prop is balanced and a good break-in size prop would be a 12x6.
Adjust high speed needle with throttle wide open. Worry about the low speed needle after break-in.
It would be best to first run it on a test stand rather than your profile plane. It going to be spitting alot of oil and no need to goo up your plane.
