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Cox RR-1 needle valve setting?

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Old 07-14-2013, 03:30 AM
  #1
jp1961
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Default Cox RR-1 needle valve setting?

How many turns should a Cox RR-1's needle valve be backed out to run? I can get the engine to run for a second with prime, but not run.

Also, was there a tiny O-ring on the fuel tank trumpet right where it goes into the backplate?,,,there seems to be a small channel in this trumpet.
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Old 07-14-2013, 04:29 AM
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Jim Thomerson
 
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Default RE: Cox RR-1 needle valve setting?

I don't know, and suspect it varies from engine to engine. I'd suggest opening it a full turn, giving it a try. Open it some more until it works.
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Old 07-14-2013, 11:35 AM
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Default RE: Cox RR-1 needle valve setting?


Quote:
ORIGINAL: jp1961


Also, was there a tiny O-ring on the fuel tank trumpet right where it goes into the backplate?,,,there seems to be a small channel in this trumpet.
Thanks

Yes there should be a small black O-ring style gasket there-and without it you will get exactly the symptoms you describe-running on prime but won't continue running. [because the O-ring is there to seal the joint-without it you will have no- or minimal suction!] I would expect the correct needle setting to be around the 4-5 turns open for starting (it's a very fine thread remember) and running about 3-3 1/2 turns open

You can get the O-rings from Cox Int'l-they're the same as those used in the tanked 049 reed valved models (you may have to buy a complete overhaul kit-I'm not sure if they sell them individually......packets of 10?) Some people make their own by slicing thin pieces off silicone fuel tubing-but this is a fairly hit and miss way of doing it-and a degree of precision is required. Also it would pay to check the needle tip closely-preferably against another one known to be 'good'-it is possible to break the extreme tip off these needles if they are overtightened when fully home-and that does nothing for the function! [look at it under a decent magnifying glass]

Good luck!

ChrisM
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Old 07-14-2013, 12:47 PM
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jp1961
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Default RE: Cox RR-1 needle valve setting?

Thanks ChrisM,,,appreciate it!!

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Old 07-14-2013, 12:53 PM
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Andrew
 
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Default RE: Cox RR-1 needle valve setting?


Quote:
ORIGINAL: ffkiwi


You can get the O-rings from Cox Int'l-they're the same as those used in the tanked 049 reed valved models (you may have to buy a complete overhaul kit-I'm not sure if they sell them individually......packets of 10?)
ChrisM
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[link=http://www.exmodelengines.com/cox-.049-venturi-gasket-3.html]Ex Model Engines[/link]

[link=http://coxengines.ca/cox-.049-venturi-gasket-3.html]COX International[/link]

Both locations also have them in bulk packs of 10.
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