Filitup,yah i went to the store yesterday and i read the specification son the box to the mx500 an dit said 650W motor.
so if i keep the same stock gear ratio and 48v will that be okay or od i have to cahnge it?
Ok, I finally got a chance to try out the new 90t Currie rear sprocket on my son's MX1200(MX500 Razor Dirt Rocket) mini bike..The best thing for dirt & jumps, will be a higher ratio. A higher ratio will give more torque and make less heat on the motor. Stock, the MX bikes come with 80t rear / 11t front = 7.27:1 ratio. You should be able to go 17mph as soon as you buy it.. When you upgrade to 48v, the motor will spin faster, so you will probably end up seeing ~24mph..
Sprockets / ratios: There are a few ways to get a higher ratio. Unfortunately, none of them are direct bolt/screw on's, because the 80t rear sprocket is the biggest direct bolt on, and the 11t front sprocket is the smallest direct bolt on.. But, I have had some success modifying smaller front sprockets, to lower the ratio. You can buy 25P(the size) 9tooth & 10tooth 1/4 in diameter front sprockets from the surpluscenter.com web site for <$2 each, then tap them to screw onto your motor shaft. *For dirt, I would go with the 9t, 80t/9t=8.9:1 ratio... This combo at 48v/650/750w motor will give results like my youtube videos, and go ~18-19mph top speed... You can also buy a pre-taped 8t front sprocket off of ebay for ~$10 that will screw right on. But this 8t sprocket is a re-reversed(tapped twice) sprocket, and therefore it is a bit loose and the threads are week. My 8t worked fine at 36v, but when we went to 48v/750w motor it stripped out the second day.
Now, the other option is to buy a Currie scooter 90t rear sprocket, ~$20, this would give you 90t/11t-8.2:1 ratio - and ~20mph top speed. *The 90t Currie rear sprocket will need the center hole enlarged to fit your hub, which will require a little bit of drilling, and patience with a jig saw..(*I'm actually getting this sprocket today, and next week I will be modifying it to fit, so I can give details as how I modified it, later).
The deal on the sprockets is this: The front ones are less expensive, but need to be screwed onto the motor shaft. The threaded shaft was not originally intended for sprockets, it is for the lock nut... I have not yet had a threaded shaft snap off, but we haven’t had that combination on long enough to see how it holds up long term... The Rear 90t Currie Sprocket seems like the best way to go for peace of mind, because after you put the time into modifying it, it will just bolt onto the hub where the original does - and should be exactly like the original 80t stock one, in terms of reliability.. *I'll be able to let everyone know how the 90t sprocket works out for us, in a week or two...
If you have trouble connecting to these links, just go to youtube, and search for "mkroberge", and my videos will come up.
miker71 - Thanks a lot for sharing all this info, it is really appreciated. aproldan popinted me to this site and the information here has been great. I plan on doing some of these mods to my MX500 (and eventually my wife's bike) in the near future, I'll let you know how it all works out.
i am getting the mx650 and want to upgrade it and are new to dirt bikesFilitup,
I don't know about the 650w motor specs, but I bet it's pretty close to the 750w. My Son's bike went like ~24mph with the stock MX dirt Rocket gears setup(80tooth rear/11tooth front = 7.27:1 ratio)
*Because you are now going to buy the MX650(650w motor), this would be a good candidate to first just try the 48v upgrade(without trying the 750w motor at first). It's only advertised at 100w less than the 750w motor... If you go onto the unite motor web site, they don't even list this motor? I am personally wondering if the MX650 may really just have the 750w motor in it.
Filitup, this might be worth holding off on the 750w motor, to see if you get the same performance at aproldan and I did, before you spend the extra ~$65 on a new motor, that you may already be getting with the mx650...
If you just go without the motor for now:
~$20 Extra 12v/12ah battery.
~$40 100a/48v controller
~$38 48v battery charger
~$45 for incedentals, and shipping..
~$140 - ~$150 total for your initial upgrade..
bmj2468,i am getting the mx650 and want to upgrade it and are new to dirt bikes
and is clueless about controllers, battery's, and teeth can you help me?
OK THAKSFOR YOUR REPLYbmj2468,
Ok, the first think you should do, is read through this entire forum. It discusses a wide range of options, of modding stock MX500/650's. (*you may be able to answer most any question you have, after reading these posts.. )
*From you prior messages to me on youtube, and you are now going to buy a MX650, I'm guessing you may first want to try the basic upgrade? Good, this is always the way to start!
I'm guessing you will start by staying with the stock 650w motor, and try upgrading to 48v(from 36v stock) and a new more powerful power controller.
I suggest buying parts from TNC Scooters:
~$20 Extra 12v/12ah battery.
~$45 100a/48v controller
~$38 48v battery charger
~$40 for incidentals, and shipping (incidentals like 12 gauge wire, an Automotive fuse-able link, New On/Off switch, ect...
~$140 total for your initial upgrade..
*I would suggest leaving the gears stock at first. The 11tooth front/80tooth rear stock gears are rock solid, and with this initial upgrade, you should be able to go from stock speed of ~17mph to ~24mph.
*Like I mentioned in prior notes, you will need to watch the temperature of your motor, and you should be ok. *If you are riding mainly on flat hard surfaces, you should have nothing to worry about, but if you are doing hills, grass, and dirt - then check the motor often - and take breaks as necessary, to let the motor cool.
I also have a mx650. I am attempting the 48volt hop up based off of this forum and need your knowledge of where you put the 4 battery. Any suggestions would be great.
Also, I need 12 gauge wire, and an automotive what?
Tera,I flattened the batterybox sides, turned the bat 90 degrees, added the 2nd bat, but they do not fit. In the pics you posted, it doesn't show 2 bats on top. How did you do it? Cut the battery box frame? My batteries together need 7 3/4", which exceeds this. Also, why did you add a different on/off switch?
Tera,I would of never figured that out. Thank you for helping me. I really apperciate your time & knowledge.
I now have the batteries mounted and the controller mounted in the same spot as you.
I am having difficulties understanding how to correctly wire my YK42-4 controller. The diagram that came with it doesn't show how to wire in the brake wires, charger receptacle, on/off switch, fuasble link.
Think you could explain how to do this?
Jesse,Jesseforlife said:Hi miker, my name is jesse and i just got a mx 500 1 month ago. My town has great streets with so many of them i hope to discover with my mx 500. However, i've always thought that my mx 500 could give me more speed than what it gave me at first. So i found this site luckely for me i found this site. I have an unlimited budjet to spend on my mx 500. I want to get the most speed out of my mx 500. I do not use my mx for offroad purposes, only for speeeed!!!! I do not want to make any welding to my bike, however i am willing to spend on the motor, controler and ext... I was just wondering if you would be kind enough to answer my email as i have seen how busy u are through this site lol! I have visited the tncscooter.com website, but i would greatly appreciate if you would make me a complete list of the things i need to get tthe most speed out of my mx 500. also i have a question would this 900 watt motor fit in my mx 500 without welding link: http://cgi.ebay.com/BRAND-NEW-900-WATT-ELECTRIC-SCOOTER-MOTOR-35MPH_W0QQitemZ220142254385QQihZ012QQcategoryZ22703QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
trueawoodstar1,trueawoodstar1 said:hey, could you send me how to connect the extra battery to make a 48 volt and is there any thing else i would need to buy other than a 100 amp controller?