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08-04-2007, 08:01 PM | #1 |
RCC Apprentice
I am: Gabe
Join Date: Aug 2006
Location: Alexandria ,Ontario
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Need help with OS 70 FS
I have a used 70 fs with no manual .....What is the factory setting for the mixture control valve and the needle valve..... Right now the needle valve is set at 1 turn and the mixture control valve is at 3.75 . the engine is running ok at these settings but I can only get 7000 rpm .the idle is very good ..At top speed the engine dies when the plane is pointed upward or downward.............Thanks Gabe.....
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08-04-2007, 08:20 PM | #2 |
RCC Supreme Contributor
I am: Len, an RPAS pilot
Join Date: Sep 2003
Location: Toronto, Ont
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hi speed start at 2 turns p 13
mixture at 1/2 turn p 12 here's the manual The above settings notwithstanding, your mileage may vary. Open the hi speed a bit more (richen it). This is turning it counterclockwise when looking at the knob. At WOT, you should use a tach and richen/lean it to maximum rpms then you'll want to richen it a bit (drop the rpms by 400-600 rpms) so when in the climb, it won't starve for fuel. So, if you can peak it at say, 10,000 rpm then richen the hi speed to drop those rpms to around 9600. It's leaning out (not enough fuel) when u held it up. |
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08-05-2007, 01:30 PM | #4 |
RCC Supreme Contributor
I am: Len, an RPAS pilot
Join Date: Sep 2003
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okay, manual notwithstanding, the procedure should get you set up. Better to start off too rich than too lean.
FOr this one, hi speed 3 to 3 1/2 turns and mixture is 3 turns out. For the 70fsII (can't be much different than 70fs, if different at all) |
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08-05-2007, 04:02 PM | #5 |
RCC Supreme Contributor
I am: Andrew Coholic
Join Date: Sep 2002
Location: Timmins, Northern Ontario
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If the main (high speed) needle is out 3 to 4 turns and the low speed out about the same (with the carb nearly closed off, you should still be able to blow some air through the carb through a piece of fuel tubing on the fuel nipple) - you should be able to start up the engine at about 1/4 throttle.
Leave the glow plug ignitor on. The engine will probably be slobering rich. Open the carb to full open, slowly. Now, adjust the high speed for a clean run (if you are using a tachometer, peak the engine and then back it off a few hundred rpm) Once the engine is warmed up, say after a minute or two of running, go to idle. Let it sit about 5 to 10 seconds and if its still running advance the throttle at a moderate speed (dont jam it to full, try and advance it as fast as you would while in a plane and trying to throttle up for take off). If it quits cold, open the low speed a 1/3 to 1/2 turn and try again. Each adjustment make it less and less untill you are turning it maybe 1/8 turn at the most. If the engine sputters and coughs and raw fuel is coming out the exhaust, its too rich. Stop the engine, screw in the low speed a little (again start with 1/3 to 1/4 turn) and try it again. Once the engine can idle for a few minutes and immediately throttle up without hesitation you got it. Dont forget a 4 stroke generally makes more exhaust smoke when throttling up, even when properly set, than a 2 stroke. Its not that difficult if you understand what the needles do, and approach the issue with some direction. Set the top end, then the idle, then reset the top end. This of course assuming the engine is broken in already. If not, start with some rich break in runs first and dont worry about a perfect idle untill you at least seat the ring for 1/2 to 1 hour. AJC
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Andrew Coholic -MAAC #26287L 1/2A to giant scale, IMAC, SAM, R/C sport, turbine jets, Heli's... if its got a wing or two and an engine - I like it! |
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