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Apr 06, 2019, 09:38 PM
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Robert Pulse's Avatar
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Hobby king quick 540 outboard


Anyone played with one of these $37.00 outboards? Thoughts on it if you have.
Bob
Last edited by Robert Pulse; Apr 06, 2019 at 10:10 PM.
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Apr 10, 2019, 02:37 AM
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BenVK's Avatar
It's the same unit that came with the HK Hornet boat which I've got.
It's moulded plastic and the skeg is prone to snapping off so I wouldn't recommend it, especially since you can now get this CNC aluminum outboard instead.
https://hobbyking.com/en_us/cnc-alum...___store=en_us

This is another option which I've used on a custom build tunnel hull. It's a decent bit of kit but notice that the leg extends much further aft than the one above. The turning ability of the boat does suffer because of the increased distance from transom to prop. Well, in my experience anyway but I guess it depends on the design of the hull and other factors.
https://hobbyking.com/en_us/sprint-f...___store=en_us
Apr 10, 2019, 01:57 PM
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AirDOGGe's Avatar
Sample video of outboard in question in operation. His skeg is history if he keeps getting so close to shallow shore at high speed like that.:

Hornet Formula-1 Tunnel Hull with 540 Outboard Motor R/C Racing Boat (750mm) (3 min 26 sec)
Apr 10, 2019, 10:06 PM
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Robert Pulse's Avatar
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540 outboard


Quote:
Originally Posted by AirDOGGe
Sample video of outboard in question in operation. His skeg is history if he keeps getting so close to shallow shore at high speed like that.:

https://youtu.be/4U5_exSgNag
Any idea what motor is in the outboard?
Bob
Apr 10, 2019, 10:57 PM
Just Plane Nutts
AirDOGGe's Avatar
Quote:
Originally Posted by Robert Pulse
Any idea what motor is in the outboard?
Bob
Boat specs according to HK:
(no longer in production)

https://hobbyking.com/en_us/hornet-f...oat-750mm.html

Length: 750mm
Width: 280mm
Height: 200mm
Motor: 2858-1400kv Brushless outboard motor
ESC: 50A
Servo: 1 x standard size servo
Battery: 2~3S 4000mah to 5000 lipo battery (Not included)


That is a low KV for 2S or even 3S power, so question is can the drive handle more RPMs without failing?
1400KV x 11.1V = 15,540 max RPMs.

Owner says using 3S 5000 mAh Li-Po in the video. No mention of prop used or any upgrades so assuming stock.
Apr 10, 2019, 11:39 PM
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Robert Pulse's Avatar
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Outboard


Interesting. Wonder what the total weight was with the battery. I got the hull I wanted to use and its going to make one big center console boat. It may even fit 4 outboards.
Bob
Apr 11, 2019, 12:41 AM
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BenVK's Avatar
Quote:
Originally Posted by AirDOGGe
That is a low KV for 2S or even 3S power, so question is can the drive handle more RPMs without failing?
Yes, it can handle it. I run my Hornet on 4S, 3000kv motor, 37mm prop but it'still not that fast due to the poor hull design.

Outboards look cool but are a pain to setup and dial in. A few mm too deep or shallow, a prop 1mm too big or small and the boat will just sit there with the prop cavitating.
Apr 11, 2019, 10:47 AM
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Robert Pulse's Avatar
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Outboard


Quote:
Originally Posted by BenVK
Yes, it can handle it. I run my Hornet on 4S, 3000kv motor, 37mm prop but it'still not that fast due to the poor hull design.

Outboards look cool but are a pain to setup and dial in. A few mm too deep or shallow, a prop 1mm too big or small and the boat will just sit there with the prop cavitating.

What are you greasing it with and how often?
Bob
Apr 12, 2019, 01:17 AM
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BenVK's Avatar
I use Exus E-G01 bicycle grease after every 3 or 4 outings with my boats.
https://www.sjscycles.co.uk/lubrican...e-grease-blue/
Aug 16, 2019, 06:38 PM
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Robert Pulse's Avatar
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540 hk outboard


Been a while since I posted here. I have been working on three of them for a while when I felt like it. I have been doing a little fiddeling with them, trial & error. What I ended with runs on a 1.5 volt battery. I first added a peice of brass to reinforce the steering. Then added two micro washers 3mm to each side between the motor and mount. I then added two 3mm washers to each post of the motor mount rear posts and one to the front posts between the lower unit and the posts. The front has the steering reinforcement so they only need one. I then connected the flex shaft to the coupler.
Before tightening the coupler to the motor I used the dubro washer packaging cardboard between the motor and coupler, single thickness That was done before installing the motor to the mount. The flex shaft was also greased prior to assembly. Some of the lower unit screws were stripped so I replaced them with the smallest brass wood screws I could find. I did have to cut the excess off the screws and file them smooth with the lower unit. Before I installed the cowel, I had to cut a slot for the steering reinforcement. I made for the motor as I made it wider than it was Seems like a lot of work but the mods seem to make a huge difference. I could have shortened the coupler but as hard as parts are to get I opted to do what I did. While I was playing, I added aluminum tube around the motor for cooling and drilled an exit for the cooling water through the cowel. That had to be done while the cowel was screwed together. I used a 7/32nds drill then a 3/16th. Now I only have two more to do.
Bob

I would really like to make a cowell that isnt so big, maybe vacuum formed. Maybe down the road.
Last edited by Robert Pulse; Aug 16, 2019 at 07:24 PM.
Aug 23, 2019, 03:05 PM
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Robert Pulse's Avatar
Thread OP

center console


Motor mockup done, Motors all wired, greased, ready to mount on the boat. I made a stand to setup the motors so the Skegs are all parallel
Now on to the boat.
Aug 24, 2019, 09:25 PM
Registered User
the 540 outboard can run fast but snaps flexies easily.....

the CNC motor is even worse for breaking shafts, just too short a radius in that lower unit period.

the most reliable is the sprint, the flexies dont break near as often, but i have upgraded the motors on the sprint to a leopard and am now happy

just so you know I have upgraded flexshafts on all the outboard motors, still the stock sprint is the best


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