OS65 not reaching high RPM

by Dominic Christopher
(Abu Dhabi - UAE )

I have an OS65, and it just does not seem to reach a high RPM on max throttle. Tried adjusting the mixture screw both ways but either the engine has no power (when air mix screw is opened more than 2 turns)or starts dropping power if I go beyond 11/6 to 1 1/8 closed mix screw.

Also the little screw on the left side of the carb was adjusted so I am not sure if that could be a reason for the engine not gain a higher RPM. All servo linkages and travel adjustments are ok. (would also like to know what that little screw does?)
Would appreciate your kind advice.

Best Regards
Dominic

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Age of engine?
by: rcdude07

How old is the engine is my first question.

You should start by screwing in the needle valve all the way, then back it out about 2.5 turns and then minor (like 1/8 turn) adjustments from there to get to max RPM, then back it off a few hundred RPM.

What do you mean by the little screw? There's also a low end adjustment, which is typically a screw on the opposite side of the throttle arm. This is used after getting the top end tuned and needing to adjust idle and/or transition from low to high speed.

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OS65 not reaching high RPM
by: Anonymous

Hi RC Dude07,

thanks for your inputs, will definitely try it out. The little screw I was referring to is located on the left side of the engine(OS 65AX) just in front of the air mix needle.
Cheers!

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Link to pic?
by: rcdude07

Can you link to a picture?

To meet sounds like that may be a screw that holds the carb on.

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OS65 not reaching high RPM
by: Anonymous

Hi, check this link out:

http://www.osengines.com/engines-airplane/osmg0548/

You will see a little screw in front of the air mix needle which is also inline with the carb.

Cheers!

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reset and retune
by: rcdude07

Ok, that's the mixture adjustment i refer to as low end/low speed. The manual for the engine is linked on that page you linked.

http://manuals.hobbico.com/osm/46ax2-manual.pdf

There is a section about tuning it. I'm guessing now you're out of stock config. My recommendation is to set both mixture controls back to stock and retune from there.

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Post Your Comment For: OS65 not reaching high RPM
by: Anonymous

Thanks for the tip, will tune back to stock setting and then take it for there...Thanks a ton!!

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Needle Adjustment
by: Anonymous

The big needle is easy (2 Turns Out)
How many turns to the "Mixture Control Valve"

FACTORY SETTING IS ..... WHAT???

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