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Racerstar 5065 140kv? or 200kv?


#1

This may be a total noob question but I just don’t understand… The Racerstar 5065 140kv brushless motor lists specs for 140kv and for 200kv, so when is it a 140kv motor and when is it a 200kv motor? Or are there two different Racerstar motors, both with the same 5065 identifier and different kv ratings, so they just always list specs for both? And if the latter is the case why wouldn’t they just give each motor a different identifying number? Any insight into this would be much appreciated.


#2

Two different motors. Use a calculator to see what you need. Top speed and torque are going to be a tradeoff, you trade one for the other. 140kv generally is probably better for those motors if your wheels are over 98mm in diameter


#3

Drop some knowledge @b264 yo
What he said :arrow_up:


#4

Thank you @b264. I have 150mm wheels and I do have the 140kv version. So any idea why they wouldn’t just use a different identifying number (5065) for the motors?


#5

5065 means 50mm diameter and 65mm length. It’s a standard size, along with 5055, 6355, 6374, 6384


#6

Thank you again @b264. May seem like trivial info but to me, less confusion = less headaches. I appreciate the knowledge.


#7

One word of caution.

The mounting holes on the racerstar are not the same as a lot of the other 63xx motors. As such some motor mounts will not work. Make sure you check the specs for both motor and mount before ordering.


#8

Yeah. 5065 is the physical size. and Kv is how fast it spins per volt supplied.

140kv spins 140 rpm per volt. so at 10 volts it spins 1400 rpm.

5065 is more the can size the motor is actually close to 70mm long if you include the nub at the end.


#9

Thanks @ervinelin and @Irdesigns. Two of them fit on 10" trucks and mounted fine on the $7 HobbyKing motor mounts - only with two screws but they’re holding just fine… no slippage or belt slack and the motor mounts don’t budge either and they’re short I only have to use 280mm belts with 15t & 40t pulleys.


#10

@Soulnatcher Take a serious look at these 5065 motors…they are 170kv which is even better


#11

Careful… I stopped relying on two because of slippage after a while…


#12

@ervinelin What does that mean? What exactly is “slippage” and why would two motors cause it?


#13

@b264 Why is 170kv better? Can’t I get same speed results by changing gear ratio? I was under the impression (not saying the impression I was under is correct lol) that 140kv was ideal because they can provide more torque which you can trade for more speed by changing gear ratio which is not conversely true as you cannot trade a higher speed motor for more torque. Please explain and please don’t hesitate to tell me how wrong I am (if I am) and why… Thank you.
Ps I haggled with a seller on AliExpress and got three 5065 140kv motors for $54 total because I actually only paid for shipping not for the motors.


#14

@ervinelin Oh ok. Sorry I was retarded for a minute, you meant slippage on the motor mounts using only 2 screws right? Ya I was kind of worried about that at first too but if you take a small thin file & rough up the motor mount a little where the motor sits on it and rough up the motor a little where it sits on the mount it provides a lot more grip then take a hack saw to the top of your two screws used to mount the motor to deepen the groove a little then use a correct size standard screw driver you can get a lot more torque when screwing them tight, in combination with a couple drops of red thread locker they aint goin nowhere.


#15

If it works for you no problem, the HK mount is cheap as beans…


#16

@ervinelin Ya they seem to be working fantastically. I was worried that at the price they might be flimsy and/or slip easily on the trucks but really they are well designed, very light, too short to really be flimsy, and have a death grip on my trucks which is no easy task as i have Paris trucks which are perfectly round and very slick and I didn’t file on them at all before securing the mounts. I’m really quite impressed with them. I’ve paid a lot more for parts I’ve been a lot less impressed with.
One thing I am having an issue with is battery usage. If you weren’t already aware, I just changed over from a 600w brushed dc single motor setup to this two 140kv brushless motor setup. Now my board is quite a bit lighter, I’m getting about the same speed and torque I had before, but only about half the range. I thought the brushless were supposed to be way more efficient and on top of the much lighter board I thought my range would increase… Any ideas or thoughts on this issue?


#17

I like the lower kv because it allows you to run a lager motor gear for a given top speed, this results in longer belt and pulley life.


#18

In theory, yes – but not all pulley sizes are available or easy to find. If you stick to the things other people are using, you’ll have many more off-the-shelf options in that regard. Also you don’t want to go too high on the kv not only because of erpm limitations on the controller but also because you don’t want any HTD5M pulley with less than 15 teeth.