Razor MX 500 build

[dirkdiggler]

Just bought another Razor MX500. I had one for my kid that was overvolted to 48v with Lipo. Pretty fast for him, but wanted something with a bit more speed when I want to ride.

Found one locally for $25. I put in a c80-100 motor and 100a Turnigy Sentilon HV ESC. I hooked up a servo tester to the Razor throttle. Took a while to figure out the throttle wiring. Razor has a rainbow of colors for their wires. I am using a 17 tooth gear on the front. I didn't count the rear sprocket, thinking 60 or so. I had to add an extension to mount the motor to the existing motor mounts. Took all of an hour or so to get it up and running. Would have been quicker if I didn't have to monkey with the throttle wires. Easiest build I've done. Still need to solder my connections and secure the ESC and batteries. I bought the ESC and motor for about $100 used. Total cost $125. The used Razor market is great for cheap builds. Everyone seems to have dead batteries (an easy fix with lipo) and most are in good shape.

First GPS speeds have been around 25mph at a little over half throttle on 6s. I want to make sure everything is working first before I check out the max with 12s. I will tone it down for my son though. I will likely gear it down so it climbs hills better.
Thanks to this thread for the motivation:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=51258
I couldn't find a hubmotor that cheap or I would have tried.

Here are some pics:

 

[Silenthunter]

Looks great mate!!! I have been looking for this motor and no success. Where did you get it?

 

[Dauntless]

So I have 3 of those bikes, as well as some of those motors I'm still trying to figure out how to install on ANYTHING. Is that the bracket that came with the motor? Did it JUST HAPPEN to bolt where the old motor was, or did you do some welding?

 

[gwhy!1]

Unless you have a outrigger bearing on teh end of that motor it will get ruined in no time , it needs to be supported.

 

[Dauntless]

Any suggestions on that?

 

[dirkdiggler]

:wink: I think it will hold up for my 50 lb kid. There is bit of flex on the mount, and the chain tensioner limits the stress on the motor shaft. The chain will pop if the shaft ever really gets torqued. I've put this motor through much worse. This could be the final straw that breaks it, but it hauls and is fun even for me. I think the Razor frame will fall apart before the motor does. I'll update you when either of those happens.

 

[dirkdiggler]

Sorry Dauntless didn't see your question. I bolted one side of the motor's mount to the existing Razor mount. On the other side I added a two holed extension to get to the other mount on the bike. There is another mount spot on the front of the motor that you can use to add a bearing support if you want. The motor was just sitting around so I thought I'd put it to use. A bearing support isn't expensive, but will take longer to get here than my interest in the project. You can find some on Surplescenter. I am hoping to build a real MX bike built in the future. The Razor frame won't handle an adult weight for very long. The shocks are also horrible for anyone bigger than a popsicle. Like I said I think a 50 pounder should do fine until he needs a real bike. I could be wrong or I couldn't.

 

[Dauntless]

I totally missed that extension right there in plain sight, didn't I?

Meanwhile, GWhy! can explain how simple this bearing would be to make you feel like it's less bother than you thought and maybe totally worth it. This site is about the how to.

 

[dirkdiggler]

Any suggestions on the bearing support? Looks like my son is going to be riding it more than I thought. I'm finding it hard to not ride it either. There is a frame mount about 2 1/4" away I could use. You can see it in the pics.

 

[Dauntless]

I started another thread on the bearing subject, no response. I would guess that means it's unexplored at this time.

Outrigger bearing for an outrunner motor: I guess there's no mounting it on the housing. My own thought is that you're needing to mount it PERFECTLY in line with the shaft when the motor is mounted. Just some arm coming off that mount is probably plenty. Then again with the right bearing maybe you could use the same mount as your motor.

There's pictures here, but you have to log in to look at them. This is radio controlled boats with Hobby King motors, up the right alley.
http://forums.offshoreelectrics.com/showthread.php?43402-Predator-outrigger-Thrust-bearing-or-thrust-washer

 

[Dauntless]

http://endless-sphere.com/forums/viewtopic.php?f=28&t=53891

A response on the outrigger bearing, with the need to be sure that if there are internal bearings on the motor you get a good alignment with them on the shaft.

 

[robnewyork]

love it!

 

[Tench]

I totally agrre with Gwhy, the motors power pulling on the chain will break the motor mount!! just a simple plate with a hole bored in it to accept a bearing with an I/d to suit the motor shaft bolted to that lug in front of the motor would do the job perfectly, it is only to counter act the pull on the chain, that lug is positioned just right!

 

[Matt Gruber]

I'm converting my mx500 to run on 4-6 makita packs. ordered a new controller with 2 speeds, 15 or 20 amps for $10.
4 packs will swap in from my E300 scooter. MX500 should go a lot better since it won't get stuck in the sand, i hope.
Will be a lot lighter without those SLA's.
Will use an 80 amp relay for safety
UPDATE:
got 2 new dewalt DCB204- 4ah packs on sale 2/98 free ship. mx500 works great! i don't see anything wrong with the stock motor!

 

[yawstick]

Hadnt seen this thread before... me thinks you need a lot more reduction to get best power from this motor... especially if you are going to go to 12s. Before I tried to rig an outboard bearing I would try to mount the motor where you could take power from the other end where the mount is. I would also be inclined to add a jackshaft with more reduction rather than add outboard bearing. Just my two cents worth.