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Old Aug 01, 2005, 09:12 PM
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Aten W Arthog's Avatar
Joined Sep 2002
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Sky Scooter Pro II ; Need advice on re-motoring.

My Sky Scooter is completely stock but for a paint job and I like it just fine. Well, I enlarged the battery area to fit packs one cell bigger. But the motor/gearbox/prop and ESC are stock. Have flown it for 2-3 seasons now. Had a great day out with it today, dead calm, about 8o degrees near sunset. Flew the stock pack it came with, then ran the bigger pack which I used all last season without probs. Only got about a 6-minute run before losing climb power, instead of the 12 or so I was expecting. I put it down to not recharging the batteries until just before leaving for the field. Packs are a stock 8.4v 600ma 7-cell sanyo and a bigger 8-cell KR-1400 1400ma AE sanyo pack. Came in to land, tried the throttle again to run the pack down the rest of the way to auto-cutoff before cooling and re-charging them, something I always have done.

Smoke is not supposed to come out of the motor, I'm pretty sure.

The thing was HOT, it melted a couple of centimeters of EPP foam all around the casing inside the plane. Even after disconnecting the battery and driving home for 15 minutes, the gearbox area underneath the prop was too hot to keep my finger on. ESC and servos still seem to work fine. Here come the questions:

1: is this the typical failure mode/lifespan for cheap speed 400 type motors?

2: do you think the gearbox is bad too, and:

3: I really don't feel a "need" to hop-up the scooter's stock performance, so I'm looking at just replacing the motor with an identical one - do you think this is wise, or should i replace the whole motor/gearbox as a unit? Cost is a factor. As is simplicity of the repair, not crazy about fiddling with pinion gears. Not wanting to go brushless for this.

4: will entertain any further thoughts/suggestions from other Scooter owners.

5: thanks!
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Old Aug 01, 2005, 09:25 PM
Registered User
Central California
Joined Aug 2003
1,137 Posts
A very cheap upgrade is a Zagi motor with the stock gearbox and prop. You can tell by looking whether yours is worn or not. Don't throw your pinion gear away.
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Old Aug 01, 2005, 10:14 PM
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Joined Sep 2002
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What's the best way to take ou the gearbox and motor?
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Old Aug 01, 2005, 11:15 PM
sitka's dad
Dallas, TX
Joined Nov 2002
81 Posts

Loosen the ESC to slacken the wiring to the motor.
The motor and gearbox is hot glued into the fuselage unless someone
modified it.
Use an xacto knife to cut the hot glue around the gearbox. If the motor
has glued itself into the fuse - just cut out the motor as best you can
without destroying the foam.
If you like the performance of the stock unit - stay with it. Chances are
the gearbox is ok. If you have to replace the gearbox - you will need a
gear puller to remove the pinion gear from the motor shaft to place it on
the new motor.
If you want to increase performance without a major motor purchase -
consider moving up to a 480 motor ... it is slightly stronger than the 400
without major modifications. You should be able to stay with your stock
ESC and batteries.
One point about flying electric ... if you never buy another tool ... consider
an amp meter. It will save you many dollars in the future.
If you increase the performance of your scooter ... consider routing more
cooling air to your motor. Do not cover up your ESC under any circumstances.
One way to get more air to the motor is to remove foam from the left side of the
fuse across from and behind the motor. Some pilots mount a scoop to that side
to funnel air across the motor.
A point about your battery. If you increased the number of cells and or the mah
rate of the new battery ... consider that the increase demands a slightly smaller
prop. Or you can just reduce the pitch sometimes.
When you went to the larger battery - you added to the amp draw of the motor.
Everything is heating up. If you want to stay with the folding stock prop but run
a larger battery pack ... just trim the tips of the prop down to the next size or
buy a replacement prop and use one for each pack.
The hitec website used to have a hop up page for the sky scooter.
This one is at servocity ... http://www.servocity.com/html/sky_sc...fications.html

Just have fun no matter watt ...

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Last edited by dickj; Aug 01, 2005 at 11:28 PM.
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Old Aug 01, 2005, 11:20 PM
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Aten W Arthog's Avatar
Joined Sep 2002
1,069 Posts
Thanks for the quick and very detailed response! I'm not crazy about re-propping every time I change battery packs though. You know, if 2-2.5 seasons per motor is the failure rate, I can live with that, I think!;-)
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Old Aug 03, 2005, 09:15 AM
Registered User
Moorpark, Ca.
Joined Apr 2004
1,138 Posts
Check out the BIG sky scooter pro II thread over at RCU. It has all and any modificatioins you may want to perform on your scooter. One mod I would highly recommend is a cooling scoop. This will keep your motor from heating up, which lessens the motor life. 8 cells should be no problem. Donít worry about re-proping. When you take your motor out, check out the rectangular slots on each side of the motor. Cut a similar slot in the foam fuse on each side. You should be able to see daylight looking through the fuse / motor / fuse. Then take a plastic spoon and cut the handel and part of the back section of the spoon off. This will leave you with a scoop. Hot glue it on one side of the fuse over the slot you cut in. Scooters are great fliers. Good luck.
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