Tuning a Fox .15
04-23-2013, 07:30 AM
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Tuning a Fox .15
Hello all,I've just finished a scratch built sport plane and was planning on flying it in a couple of days. It's got a never run Fox .15bb (latest model) in it. I went into my engine locker and found that I've misplaced the engine instruction sheet.Could anyone who has one of these please tell me what the initial high and low speed needle settings are according to the instructions. Also does anyone who has run one of these know if it is one of the Fox models where you adjust the low speed needle First before the high speed one? I know there are a few Fox models where you do that.Thanks in advance for any responses.Robert
04-23-2013, 09:12 AM
#2
RE: Tuning a Fox .15
I do not believe that Fox gives initial settings. They run every engine on the stand and the settings are as it came in the box except the idle is on the rich side. This carb tunes like most every other twin needle carb, the ones that require the low speed mixture set first are the earliest cross flow engines. Needs fuel with 100% castor oil and about 15% nitro.
04-23-2013, 10:19 AM
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RE: Tuning a Fox .15
ORIGINAL: WoodCutter
Hello all,I've just finished a scratch built sport plane and was planning on flying it in a couple of days. It's got a never run Fox .15bb (latest model) in it. I went into my engine locker and found that I've misplaced the engine instruction sheet.Could anyone who has one of these please tell me what the initial high and low speed needle settings are according to the instructions. Also does anyone who has run one of these know if it is one of the Fox models where you adjust the low speed needle First before the high speed one? I know there are a few Fox models where you do that.Thanks in advance for any responses.Robert
Hello all,I've just finished a scratch built sport plane and was planning on flying it in a couple of days. It's got a never run Fox .15bb (latest model) in it. I went into my engine locker and found that I've misplaced the engine instruction sheet.Could anyone who has one of these please tell me what the initial high and low speed needle settings are according to the instructions. Also does anyone who has run one of these know if it is one of the Fox models where you adjust the low speed needle First before the high speed one? I know there are a few Fox models where you do that.Thanks in advance for any responses.Robert
As has been said they tune the same as any other 2 needle carb. But there is one caveat on these engines that you should be aware of. They are not like an OS. Fox engines require a run in period to seat the piston/liner. About 25% oil and short runs. You may be inviting a disappointing flying session or at worst an engine ruined before it was given a chance.
04-23-2013, 10:30 AM
#4
RE: Tuning a Fox .15
Actually the modern Foxlapped iron piston engines are an exception to that. They break in much quicker than the ringed engines, though not as fast as an ABC engine. Mine ran ok with a fast idle and flying with a rich mixture after about 4 4 ounce tanks. But took several more tanks before it would have a slow idle. 25% oil is fine for break in but after that 20% all castor is OK.
04-23-2013, 12:08 PM
#6
RE: Tuning a Fox .15
I could not open that site, perhaps at home Ican. 
But I did find on online for the older bushing version and the needle settings were not given, which is typical for Fox. Also Idiscovered that the bushing version had the older gotta adjust the idle first carbs. The first bushing versions may have this carb as well.BuyIf you have the latest (as you say) square MKX carb that comes on them now then it should adjust like any other.
But I did find on online for the older bushing version and the needle settings were not given, which is typical for Fox. Also Idiscovered that the bushing version had the older gotta adjust the idle first carbs. The first bushing versions may have this carb as well.BuyIf you have the latest (as you say) square MKX carb that comes on them now then it should adjust like any other.
04-23-2013, 12:23 PM
#7
RE: Tuning a Fox .15
Please check to see if it opens. It does for me! The site tells about propping, glow plug, fuels, and yes the older carb. Of note is the fact that most Fox engine's come run from the factory, so the settings out of the box are close...
04-23-2013, 01:51 PM
#8
RE: Tuning a Fox .15
My high speed is at 3 turns with the BB one. I am not checking the low speed one because it idle's great and I don't want to wreck it. It is likely an older one.The instructions say to do the low mixture first. I like the recommending of a wood prop becuse it doesn't hurt the finger as much. Good old Duke. This is the first Fox that I like. I made up a new Turbo head from an old burned out Rossi insert and it runs 1700rpm better than with the stock head. (likely the lowest compression one)
04-23-2013, 04:14 PM
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RE: Tuning a Fox .15
I have one of these. It is a great little engine. The R/C carb is outstanding. It throttles very well indeed. Dual ratchet springs which on my example needed to be eased off a little. The knurling on the thin section knobs offer a lot of purchase to your fingertip when the needles are adjusted. No "wandering" needles or fuel leaks with this one.
Here it is wearing a DDD head.
Here it is wearing a DDD head.
04-23-2013, 09:38 PM
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RE: Tuning a Fox .15
Thanks all for the replies...I went to the flightline site and did find the manual (complete with needle settings)I do plan on running five or six tankfulls of fuel through it before trying to fly it. The fuel is Fox's own gold fuel 5% with 20% all castor.Hey Fiery, I bet that diesel version is Powerful! Good photography of it too...Robert (WoodCutter)
04-24-2013, 04:29 AM
#12
RE: Tuning a Fox .15
ORIGINAL: WoodCutter
Thanks all for the replies...I went to the flightline site and did find the manual (complete with needle settings)I do plan on running five or six tankfulls of fuel through it before trying to fly it. The fuel is Fox's own gold fuel 5% with 20% all castor.Hey Fiery, I bet that diesel version is Powerful! Good photography of it too...Robert (WoodCutter)
Thanks all for the replies...I went to the flightline site and did find the manual (complete with needle settings)I do plan on running five or six tankfulls of fuel through it before trying to fly it. The fuel is Fox's own gold fuel 5% with 20% all castor.Hey Fiery, I bet that diesel version is Powerful! Good photography of it too...Robert (WoodCutter)
Unless you know the needle has been messed with, don't set it to the manual settings. They are likely where they were adjusted when Fox did the test run.
