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inverted four stroke

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Old 06-24-2012, 09:51 AM
  #1
BKUNZE
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Default inverted four stroke

I have a four stroke OS FS-120S-E engine mounted inverted and despite many high and low needle adjustments, the engine has a rough idle, poor transition to high speed and tends to quit after a short idle time. It does however, run well above idle speed. I have been told that a hotter plug such as the Mccoy mc-14 plug will solve the problem. I am presently using the OS type F plug. The Mccoy 14 plugs seems almost impossible to find but will this solve my problem?

Bill
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Old 06-25-2012, 06:10 AM
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Bax
 
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Default RE: inverted four stroke

We've never used a McCoy plug, so we cannot tell you anything other than to try it and see what happens.

Usually, inverted running can be problematic with all glow engines at lower throttle settings. You usually wind up with a higher idle speed to keep the engine running, or you add an on-board glow plug battery that turns on at low RPM. Many times, just getting the idle set a bit leaner helps a lot, and then upping the idle RPM. You'd then choose a prop so that the model will be able to land at the idle setting you wind up with.

Also, please realize that many engines will get better the more they are run.
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Old 06-25-2012, 06:56 AM
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Default RE: inverted four stroke

Thanks for the good advice Bill, I'll give it all a try.
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Old 06-25-2012, 09:42 AM
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Default RE: inverted four stroke

Hi Bill, I used to have the same problem in all my OS four stroke inverted, until I placed the tank exactly in same line as the middle of the carburetor, this gave me excellent idle and excellent transition as one would expect of such excellent engines. I always use plugs OS type F in all my engines with no problems
Hope this helps

Hector
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Old 06-25-2012, 01:26 PM
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BKUNZE
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Default RE: inverted four stroke

Hector, thanks for the suggestion but I'm pretty sure that since this engine is in a Great Planes P-51 ARF I can not move the tank but I will double check. Thanks again.

Bill
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Old 06-26-2012, 06:02 AM
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Default RE: inverted four stroke

Yes, I did forget to mention that a fuel tank that's too high can cause problems with any engine installation, but especially for engines mounted in the inverted position.
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