Yamaha Electric RTR boat

[Adrianli]

Some quetions for the brushless guru here:

1) I have a unknow 540size 3.17mm shaft Brushless motor. How to tell what spec or KV it is? There is no marking or branding.

2) I have a feigao 540S 5940KV motor and a HiModel Navy 70A ESC, Is these two combination gonna work or will the ESC go kaput? If not what motor should I use. I will need a 540 size motor with 3.17mm shaft.

Thanks in advance for any help / advise

Q1) No name or marking, I also no idea. Looks like u gotta tach it against the voltage used to find out.

Q2) The KV is too high!!! Will definately burn ur esc. Wat size boat u wana push??? For the 70A esc, I suggest u get a below 3000KV 540 motor for Jet Hobby size of electric boat, 20-24". I burnt my 80A esc when I ran a 540 7L 3500KV on my Yamaha on 3S lipo. Now its on 2S lipo n 100A esc, sweet setup, no burns n motor/esc ran cool. Only thing, Yamaha boat hull cannot take the speed!!!

I suggest u read up at RC Groups, RC Universe and Rumrunner for their electric boats. See how those ang mo run their boats, esp SW26 or SV27 threads. FYI, they r using XL type of 540 BL motors or 700 brushed motors.

I saw their fav 540 BL motor is 7L n 8XL. 8XL is a most wanted motor by both monster truck n boat owners, always out of stock!!! I'm looking for one too!!!

[Frank]

Some quetions for the brushless guru here:

1) I have a unknow 540size 3.17mm shaft Brushless motor. How to tell what spec or KV it is? There is no marking or branding.

2) I have a feigao 540S 5940KV motor and a HiModel Navy 70A ESC, Is these two combination gonna work or will the ESC go kaput? If not what motor should I use. I will need a 540 size motor with 3.17mm shaft.

Thanks in advance for any help / advise

1) run it at a know rpm and measure the voltage with a DVM. Divide and you get the kv.

2) Kv too high. More suitable for rc cars.

[X34]

Just adding 2 sense to boats setup.

Beside motor kv, number of cells, one must also consider propellor size. Like an airplane, must reduce pitch and diameter to bring down the amp draw at high kv.

To go fast, we want motor to spin at 50,000 rpm. To achieve that rpm without burning anything, need to use a smaller prop or cut down existing prop to reduce the amps.

Secondly, quality of soldering, wire length and size and types are equally important to prevent damaging of the electronic stuffs. see attached expensive lesson

[dirtdynamics]

Just adding 2 sense to boats setup.

Beside motor kv, number of cells, one must also consider propellor size. Like an airplane, must reduce pitch and diameter to bring down the amp draw at high kv.

To go fast, we want motor to spin at 50,000 rpm. To achieve that rpm without burning anything, need to use a smaller prop or cut down existing prop to reduce the amps.

Secondly, quality of soldering, wire length and size and types are equally important to prevent damaging of the electronic stuffs. see attached expensive lesson

Thats a schulze!

OMG... Sorry for the loss

[Adrianli]

Sold away my Feigao 540L 7T motor and got the HXT 36-56 2700kv Brushless Inrunner (WaterCooled). Ran it at Bishan Park juz now on 3S n 4S lipo. It was as fast as the feigao. Uncontrollable at full throttle, motor was cooled after continuous 5min run.

As I was using 3S2P, the rear is rather heavy n fly through the water much better. 4S lipo was really insane lor, pilot cannot control boat properly.


HXT 36-56 2700kv Brushless Inrunner (WaterCooled)
Kv: 2700rpm/v
Required ESC: 80A
Voltage Range: 10-18v
No Load Current: 4.9A
Max Load: 68A
Max Power: 475W/60S
Weight: 317g
Shaft: 5mm

Motor has an inbuilt water jacket.

[Mad Armour]

Sold away my Feigao 540L 7T motor and got the HXT 36-56 2700kv Brushless Inrunner (WaterCooled). Ran it at Bishan Park juz now on 3S n 4S lipo. It was as fast as the feigao. Uncontrollable at full throttle, motor was cooled after continuous 5min run.

As I was using 3S2P, the rear is rather heavy n fly through the water much better. 4S lipo was really insane lor, pilot cannot control boat properly.


HXT 36-56 2700kv Brushless Inrunner (WaterCooled)
Kv: 2700rpm/v
Required ESC: 80A
Voltage Range: 10-18v
No Load Current: 4.9A
Max Load: 68A
Max Power: 475W/60S
Weight: 317g
Shaft: 5mm

Motor has an inbuilt water jacket.

Side track. Is there a need to orientate the water in/outlets properly? To prevent air lock?

[Adrianli]

No need at all. The water shoots out as usual.

[skyblueblue]

Wow !! very nice looking motor. Bo jio buy together

[Mad Armour]

No need at all. The water shoots out as usual.

If water dun shoot out you'll be in trouble liow! Wat I mean is as much as 50% of the cooling space inside can be filled with air should water in/outlets not oriented properly. Make sense?

But is a very chio motor. Bling bling.

[Adrianli]

I dont have any x-ray machine to see in so not sure on that. But when installed at an angle, as per mono hull, water should enter n fill the empty space b4 exit.

As I saw the water is shooting out n not juz peeing, I assume that the water inlet pressure n volume is more than the restricted water outlet. Thus causing the water to shoot out.

If water did not shoot out, instead it juz flows out then there maybe empty space in the water jacket. Furthermore the motor is cool even after the runs. However the batts r fricking hot. I did lots of burst runs from standstill.

[Mad Armour]

Just a suggestion. IMO, it's best to orientate the outlets to one at the top and the other at the bottom. Attach the water inlet tube at the bottom and outlet tube at the top. This way, water will fill out the bottom first and pushing out air via the top. Think should be able to get the least airlock this way.

[Adrianli]

Thks for the info.

I placed them side by side. Its a hussle to re-orientate them again due to the very tiny space to work in. Will do that when the next maintenance is due.

[Ghostfit]

If water dun shoot out you'll be in trouble liow! Wat I mean is as much as 50% of the cooling space inside can be filled with air should water in/outlets not oriented properly. Make sense?

But is a very chio motor. Bling bling.

Make sense to route the inlet at the bottom and outlet at the top .....this way, the jacket space will "fill up" with coolant before it exits at the outlet

I got a similar looking 3300KV motor ........got a SHOCK when ask the manufacturer what esc is recommended ....at least 100A ESC !

Adrian, ....did you noticed that those dumb dumb 'pple at the factory soldered the motor connectors on the wrong ends ? !

[Adrianli]

Adrian, ....did you noticed that those dumb dumb 'pple at the factory soldered the motor connectors on the wrong ends ? !

Nope, mine was correct as in the pic. I also tried pulling the connectors, juz in case the soldering was a cold joint. No problem at all.

I ran 2 x 3S2P n 1 x 4S pack yesterday. Spent 2hrs at Bishan.

The problem is tis motor is rated for 3S n above, therefore cannot take part in the 2S boat race.

[Palladine]

Hi Adrian

Is there a difference when you run 3S1P and 3S2P, I assume it should be the same speed except the run time will be shorter for 3S1P. Am I wrong ?