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razor mx500 or mx650 bike lookin to mod.

9K views 19 replies 7 participants last post by  Atvrunner2 
#1 ·
Hi. i have a mx650 that i have been looking to fix up (its been 5 years since i bought this thing and i havnt really replaced parts that i needed to) and ultimately mod to increase performance. i have looked into this site and settled on swapping the stock 650w motor with a 750w motor(the biggest motor that would fit from what i have read). i would also like to improve the batteries from the stock 36v to 48v or maybe even 60v if its possible.And also if its possible, maybe some batteries that have longer run time(i think the "ah" are the battery ratings for the amount of power it contains? but i'm not really sure cuz im very well knowledged on these kind of things) I would like to know what other parts i would need to buy for a new better setup. i have heard things that i would need new controllers,throttles,fuses,etc to accommodate for the new motor and batteries and stuff. I would also like to know about the whole sprocket gear ratio thing. i have heard that changing them can improve battery life or speed or torque(not really sure).i think i'm probably gonna need some help putting all this together onto the bike so maybe someone well acquainted with the razor mx bike mods can pull up a guide for me to complete this project.thank you.Any feedback will be appreciated:D
 
#2 ·
as far as the batteries, your current pack has a fuse holder wired into it. You could always change the fuse with a 40amp from the autoparts store. snip it off the battery pack to reuse it.
study your packs wiring. the wire leads are soldered to the battery terminal. The neg to the pos the pos tive the negative. This is series wiring, it increases the voltage but not the capacity...more out put but the same size gas tank.
to charge 36v, you use a 36v charger. When you overvolt the charger becomes useless. Charging with a car charger is a flexible way to recharge. Since you are using 12v batteries, a 12v car charger is perfect. Some of them let you adjust the amp flow and battery type. Our batteries are AGM...you'll see an option for standard(wet acid) or GEL(actual electrolyte gel)...ours are AGM which is liquid stored between layers of plasdtic sheeting. Wet acid batteries are filled with the same liquid acid, but with no layers.
So you need a harness to convert your series wiring to parallel. What you do is make a harness with jumpers. you see how your original pk was "jumped" so that the batteries were connected by pos/neg. you are doing the same thing, but extended the battery leads so that they can be accessed outsuide the bike. Your parallel harness has all positive battery leads and negitive leads...6, 8, 10, however many batteries your leads are. the series harness only has 2 leads, battery #1's positive lead and your last battery in the thhain's negative lead. the other leads are "jumped" terminal to terminal with double headed connectors.

power poles are around $1each. you would need 18 of them for 36v.
6 leads for the charger, 6 leads for parallel, 2 leads a 2 double lead wires for series.
for 48v it would be 8 connecters and 3 double lead wires.
 

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#4 ·
Thats a great start. I am curious how much the 18ah batteries are? Lead acid I am assuming.
I recently installed a 36v 10ah lithium ion pack, came with charger for $165 shipped into my buddies mx650. Runtime is about an hour. Charge time is 3-4hrs.
He also has 24v 500w motor with stock sprockets going 26mph, 36v 1000w controller. Crazy, I want to build one.
Lol.
 
#5 ·
Thats a great start. I am curious how much the 18ah batteries are? Lead acid I am assuming.
I recently installed a 36v 10ah lithium ion pack, came with charger for $165 shipped into my buddies mx650. Runtime is about an hour. Charge time is 3-4hrs.
He also has 24v 500w motor with stock sprockets going 26mph, 36v 1000w controller. Crazy, I want to build one.
Lol.
Depends on the brand honestly, pretty sure you can get the cheapo 18ah lead acid batteries for roughly 35 bucks a piece. They're heavy... but if you lay them on their side and run one on bottom and two on top they fit without any modifications except the plastic battery case removal which seems mostly aesthetic anyway
 
#7 ·
Yeah the lithium ion pack is a planned upgrade for me, I just happened to get brand new 18ah lead acid batteries for free courtesy of the guy I bought the bike from so I ran with those for the time being and I gotta say I'm thoroughly impressed with the run time... even if the bike is now 800lbs heavier lol
 
#12 ·
I will chime in and say most likely it is a pit bike kick stand. And I believe you said he was running lithium's, let me tell you that's all I'm going to run after a few of my friends started running lithium. Definitely a few more bucks in the beginning if you buy the prebuilt packs but they've been going on almost a year now and not showing any signs of wearing down
 
#18 ·
Thanks for the link. Price is right too. $13 is great.

My current set up is plugging into my lawnmower/trimmer battery but that was really to get a baseline on speed and range. Spoilers: it's not enough for me haha. I picked up some NESE modules so the next part will be finding some affordable cells and BMS to pop in there.
 
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