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Old 09-28-2009, 05:41 PM   #1
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I can't get my motor to run right and need some help. This is the grp based ninja .21 . On the bottom end it will idle fine, take off fine but at top end its like its not any faster than midrange, then when i let off and just barely give it gas it starts revving high like maybe it's lean on the bottom. I'm getting plenty of smoke on the bottom and midrange, not really any smoke on the top end. My settings are 4 full turns out from closed on bottom, and 2 full turns out on top. Is this close? The motor ran great and it has sit for a couple of months, as well as my odonnel 20% fuel. Could my fuel be bad? Alot of people have told me i need to run 30%, although i don't think that is causing my problem. Last time i ran it the outside temp was about 90 degrees, now it's in the low 70's. Any suggestions?
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Old 09-28-2009, 05:59 PM   #2
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I don't own a Ninja, but I do run GRP engines. I would suggest richening the top end and see what it does. If that doesn't work, try finding the factory settings and then retuning your motor from there. Your issue could be because of the drastic change in temperature (90 degrees to 70 degrees). I posted an article from www.rchobbies.org explaining how the temperature can change the tune of a motor.

Hot weather requires a leaner mixture setting; cold weather requires a richer setting. Most people assume the opposite because they treat the mixture needle like a thermostat. It is wrong to assume that colder weather requires a leaner setting to keep heat in the engine and vice versa. Cold air is denser than hot air. The denser, colder air packs more oxygen into the engine, so going from hot weather to cold needs a commensurate increase of fuel to balance ratio of fuel-burning oxygen and the fuel itself. The opposite is true in hotter weather. Going from cold to hot weather requires a leaner mixture setting
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Old 09-28-2009, 06:47 PM   #3
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Just got back from tuning on the ninja, the richer i went on top the better it got. I ended up at 2 3/4 out and i bet i could have went more, i thaught temp might have alittle to do with the way it runs, what your saying makes sense. I will do some more tuning tomorrow. Whats your thaughts on percentage of fuel, 20% vs. 30%? I appreciate the help.
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Old 09-28-2009, 07:01 PM   #4
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I personally run Team Losi Nitrotane 30% Race Formula and have been very pleased with it. I used to run the 20% Race Formula and made the switch last indoor season. I felt a slight power increase with the 30%, but nothing drastic. A lot of people say 30% increases engine wear, but I had 18 gallons on my first GRP without doing any maintenance. If you feel you need a little more power, you can go to 30%, but it isn't that big of a deal in my opinion.

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Old 09-29-2009, 04:35 PM   #5
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the price difference is greater than the power difference.
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