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Old 06-24-2016, 12:02 PM   #223 (permalink)
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Join Date: Dec 2014
Location: Seal Beach, CA

I don't have anything to recommend other than motor I'm using. Motors and pinions for the 250 are hard to find. The shaft sizes are not common and the 0.4 mod pinions are not common. The motor I'm using actually has a 2.3mm shaft and I was able to find a 0.4 mod 15T pinion for it. I have pinions smaller and larger for that motor, but as I said I would not run any taller than the stock ratio. Though for really high head speeds you have to go taller to keep motor rpm in the correct range.

It's important for efficiency to run motor rpms 70 to 90% of nominal voltage times Kv. You also want the motor to spin 30k to 40k rpm, lower for bigger motors higher for smaller motors. If motor rpm is too low efficiency may suffer, if motor rpm is too high bearings can wear quickly and vibration may be excessive.

It's not always easy to find a motor with ideal Kv you need for the speed you want to run. About the only way to get things perfect is to find a motor that's right in terms of mechanical fit and rewind it yourself for the Kv you want. I actually rewound the motor I'm running. It was originally 3400 Kv and I rewound it to 4000 Kv.

I just remembered, I did see a 2.5mm shaft motor with higher Kv that might work, though it might be too wide, this one;
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