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Motor run problems. ESC setup?

I have a Spektrum DXe with AR620 receiver, FT 20A ESC (power pack A & F) LIPO 2S - 4S, Beta FPV 850mAh 3S Lipo battery 11.1V 35C/70C and EMAX MT 1806 - 2280 KV motor. The ESC is plugged into the 1/DATA port on the RX.

I have the TX driving the servos correctly with no problems at all. However, the motor is a different story. It stops with the throttle down, but runs slowly and with a pulsating, jerky motion when the throttle is pushed up. It never reaches any worthwhile speed, nor does it run smoothly. I’ve tried calibrating the ESC with the TX, but it doesn’t change behaviour. I’m wondering whether the ESC requires programming or other configuration, but I can’t find any instructions to this effect. It would be great to have some documentation for the ESC to tell me how it’s supposed to work and what all the beeping means!

Anyway, the most urgent thing is to figure out what’s wrong and how to fix it. Help / advice please!


Well-known member
The behavior you describe is typical of a faulty connection between the motor and the ESC (or broken wires inside the motor). Check all the bullet connectors for a loose unit (remember, the heat shrink can often hide that a connector is bad so you should tug on each of the 6, 3 ESC, 3 motor to make sure they are all sound).


Well-Known Member
Also if any of the wires between the ESC and motor are able to touch and short out, this can happen. Be sure your bullet connectors (assuming you are using them) are fully covered with tape or heatshrink and cannot touch bare bullet to bare bullet.

Never push a jittery motor. :)


Well-known member
Had this same issue a few months back due to a poor solder job I did on the bullets.

If the solution is to re-solder the bullet connectors, be sure you know what you’re doing or find someone who does. The small bullet connectors are very difficult to solder correctly and impossible if you’re a novice at soldering (as I was). I ended up having to buy a new motor with bullets pre-installed.


Well-known member
If you are having trouble soldering the bullets I would recommend a separate flux and leaded solder, both will make the job easier. You should tin the wire and the connector then use self gripping tweezers to hold the bullet connector whilst you solder the wire to it.
As above be sure to insulate properly, leave no exposed metal on either side of the connection.
You can also just solder the wires directly instead, it will work fine that way.
Well, it was the mounting screws, apparently very slightly too long. Seems to run properly now I’ve put the shortest screws in, at least mostly.

So, I revved it up with the prop on, whilst holding the plane. If I push the stick much past half-way it sounds like the motor is “slipping” and then runs a little slower instead of speeding up. It doesn’t always do this, but is worse with rapid acceleration. Is this normal behaviour? Is it something to do with me holding the plane, or is this going to happen when flying too?


Well-Known Member
Still sounds to me like a poor solder connection between the ESC and the motor.

Don't push (throttle up) a motor that isn't running right. Trust me. Burnt motor stinks. Your wife will remember the smell for a year.
I'm having the exact same problems with the same setup. When I went to the hobby store they think it's the ESC setup but we can't find a way to program it. Has anyone found a manual for this ESC because the EMAX ones don't seem to work?


Well-Known Member
EMax ESCs are popular. Lots of people use them.

When you have a jittery motor there are a few possible reasons.

If you are running eMAX red bottom 2205 motors you may need to set the eMax ESCs to a higher speed. If not, look at the following.

1. The single most common reason I have seen is a poor solder connection between the ESC and the motor. This is root cause probably 90% of the time. One cold solder joint or a loose ESC solder pad on one phase will cause a jittery motor. If your motor didn't jitter before but it does after a crash, you almost certainly broke a wire or loosened up a solder joint between the ESC and the motor.
2. Shorting bullets between the ESC and the motor. If you use bullet connectors, be sure they are properly covered so they can't short out the phases. Shorting out the phases will cause a jittery motor.
3. Motor mounting screws too long shorting out the motor from the inside. Once you have use too long screws, you may have crushed the wiring inside the motor and permanently ruined the motor. If your motor mount is 4mm thick CF, use a 6mm screw not an 8mm screw.

Some motors use enamel coated wires. This is less common today than in the past but SunnySky motors were notorious. If your solder won't stick to the motor wires when you are tinning the motor leads, you may have enamel on the motor leads. You have to burn or scrape or sand that enamel from the leads before you can tin them and before you can make the solder joint to the ESC. Failure to properly tin a motor lead or remove enamel when creating the solder joint to the ESC will result in a jittery motor.

You cannot take shortcuts soldering your motor leads to the ESC. Period. If you didn't solder the joint yourself (pre-installed bullet connectors) you really don't know if the person who made those connections did it right. When in doubt, re-heat the bullet connectors and be sure.