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Fuel coming out of exhaust? Kyosho GX-15 Tuning

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Old 07-13-2009, 05:22 PM
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Peter.Steele
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Default Fuel coming out of exhaust? Kyosho GX-15 Tuning

Okay, so I just picked up an older Kyosho car with a GX-15 engine. It has plenty of compression, starts easily, runs strong, etc., but I'm not really sure how to get this thing set up right, and the car's instruction book doesn't tell anything about the engine.

It's a single-needle carb. I've played with the mixture to where it'll start and run quite well, but really don't know what I'm doing, or even which way to turn the needle. I get a lot of fuel spraying out of the exhaust along with the smoke. With the price of nitro being what it is, I'd prefer to just have the smoke. :P

How do I correct this? Which direction do you turn the needle for lean / rich adjustments?
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Old 07-13-2009, 08:37 PM
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Default RE: Fuel coming out of exhaust? Kyosho GX-15 Tuning

i would lean it out a little, but smoke coming out of the exhaust is a good thing.
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Old 07-14-2009, 11:18 AM
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Default RE: Fuel coming out of exhaust? Kyosho GX-15 Tuning

You may not be able to do a thing about this. With just a single needle, it seems likely that fuel is blowing through on idle which you won't be able to adjust out. Besides, a little fuel coming out the stinger isn't a big deal - from a performance standpoint anyway.

The needle leans out the mixture when you turn it in (clockwise) as what you are doing is limiting the amount of fuel delivered. Be careful leaning it out, as if you get it too lean you will toast the engine.

Start the R/C up and get it good and warm - run it around for half a tank or so. Now, from a dead stop do a full throttle run and pay attention to the pitch of the engine. Lean out the needle by a very small amount: 1 hour (looking at the needle as if it were a clock) or 1/12 of a full turn. Now run around for a few seconds, then do another full throttle run. Did the pitch of the engine go up? It should because as you lean out the mixture, you will gain RPMs. You can continue to lean out the mixture, doing full throttle runs every time you do, until it stops going up in RPM's. At that point, richen up your mixture (one hour, 1/12 of a turn) by turning the needle counter-clockwise, because when tuned for max RPM's the engine is slightly too lean for good longevity.

As your engine does not have a low speed needle, it will likely be a bit on the rich side on idle. Single needle engines usually run rich on the bottom end from design. It helps prevents premature death from being too lean. Therefore, you probably won't be able to completely tune out fuel coming out the pipe.

Hope that helps.

Rob
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Old 07-16-2009, 03:28 PM
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Default RE: Fuel coming out of exhaust? Kyosho GX-15 Tuning

The Kyosho mufflers also tend to give alot backpressure. Unburned fuel and oil tends to pool at the bottom of the muffler because of the way they are designed.
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