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Dry Dock / Shipyard: Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: woodley miniman on May 30, 2012, 07:41:50 AM

Title: up grading my Robbe jet ski motor
Post by: woodley miniman on May 30, 2012, 07:41:50 AM
Hi all, I'm looking at replacing my old brushed 540 motor in my Robbe jet ski to a brushless one and make the thing go like a bat out of hell. I'm not sure what motor and speed controller to get? I've looked at the Hobby king web site and wonder if the 2040sl 4800kv brushless inrunner water cooled motor will be any good. What do you think?
Title: Re: up grading my Robbe jet ski motor
Post by: Mad_Mike on May 30, 2012, 01:42:39 PM
no the motor is too small and kv is too high. what battery do you have at the minute do you plan on changing it?
Title: Re: up grading my Robbe jet ski motor
Post by: gregk9 on May 30, 2012, 06:14:54 PM
I upgraded mine to a graupner 600 speed, with an 11.1v lipo, thats "brisk" enough for me, especially on "mill pond" water, as any wave on the water and it fights for grip at the best of times.

the main difficulty i had was removing the original drive gear off the old motor, it was heat shrunk/pressed on, not with grub screw!
it has since been drilled and threaded to accept a grub screw!

(http://s17.postimage.org/p3osere0b/DSC03403.jpg) (http://postimage.org/image/p3osere0b/)


You wil also have to watch you dont use too many revs and create too much cavitation between the props.

yes, the newer version [evo2] has a brushless motor, but props are now fixed and has a rudder for steering and props are set wider apart.  The older style u/j couplings may not takt the loading/higher rpm's.
Title: Re: up grading my Robbe jet ski motor
Post by: woodley miniman on May 30, 2012, 08:05:21 PM
Hi I want to try and use my ZIPPY Flightmax 2800mAh 6S1P 30C I have 4 that I use on my T-rex 500 and there about the same weight as the ni-cd. I plan on using the jet ski in the sea (the Solent) on a nice calmish days, maybe even give the chaps on their full size jet skis a run for their money ha! ha!
Title: Re: up grading my Robbe jet ski motor
Post by: Mad_Mike on May 30, 2012, 11:17:03 PM
you need a brushless motor around the 1000kv-1200kv region. what motor has your helicopter got in it?
Title: Re: up grading my Robbe jet ski motor
Post by: woodley miniman on June 08, 2012, 06:42:33 PM
Hi Mad Mike, sorry for the late reply, been mad at work. The motor fitted to my T rex 500 is a Align 500mx brushless motor of 1600kv rcm bl500. I've still been looking but still can't find a suitable brushless motor and speed controller for the 6s li po batteries I have. Any idea's?
Title: Re: up grading my Robbe jet ski motor
Post by: woodley miniman on June 08, 2012, 10:34:09 PM
Hi all, Just been looking on the net for the upgrade motor & esc to go with the li-po batteries I have. Do you think that this will go well in my Robbe jet ski???

motor - http://www.giantshark.co.uk/black-mantis-bm3650-900kv-inrunner-brushless-motor-p-403926.html

ESC - http://www.giantshark.co.uk/black-mantis-bm3650-900kv-inrunner-brushless-motor-p-403926.html

Batteries - http://www.hobbyking.com/hobbyking/store/__14059__ZIPPY_Flightmax_2800mAh_6S1P_30C_.html
Title: Re: up grading my Robbe jet ski motor
Post by: Mad_Mike on June 09, 2012, 01:12:55 AM
looks to me like a good combination. Thats probably what i would try. i dont know what propeller you would need though but that motor will certainly allow some room for experimentation to get the speeds you want. you may even get a 40mm 1.4 pitch on that.
 btw the link you have mentioned for the esc is the same link to the motor.

something like this will do it:

http://www.giantshark.co.uk/hobbywing-seaking-marine-reverse-program-brushless-p-403646.html

giantcod are out of those but there are some on fleabay and hobbyking do them too.

you will possibly need to watercool your motor.
Title: Re: up grading my Robbe jet ski motor
Post by: woodley miniman on June 09, 2012, 04:08:24 PM
Sorry......This is the speed controller I was thinking of using. http://www.giantshark.co.uk/black-mantis-40amp-speedcontroller-p-402906.html  With this speed controller I can use my 6s li-po's
Title: Re: up grading my Robbe jet ski motor
Post by: Mad_Mike on June 09, 2012, 04:59:41 PM
ah yes of course that one i picked wont work with 6s. btw these flight ones are forward only and youl need to add some waterproofing. I often just lather the board in epoxy seems to work fine.
Title: Re: up grading my Robbe jet ski motor
Post by: woodley miniman on June 09, 2012, 07:28:31 PM
Yes mate, with this jet ski it's going to be used in the sea so shouldn't need a reverse. As for waterproofing I might mount the ESC in a water tight box, what do you think?
Title: Re: up grading my Robbe jet ski motor
Post by: Mad_Mike on June 09, 2012, 08:02:21 PM
even better