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50cc atv conversion to electric

I have a 3y/o son who loves to ride with his sister or I on the 110cc atv the family has. I need to let him learn to ride alone. Recently I found a 50cc mini atv perfect for his size and would really like to use the mongoose m350 scooter I have or the razor mx350 to frankinstine this into an electric quad for him. My question is what system should I use to best suit what I'm looking for, both set ups seem to have a smaller chain on the motor and wheel then the quad has on the axle and engine. I'd like to upgrade to the larger chain If I could find that size sprocket to fit the shaft of the motor any and all asaisnce will be greatly appreciated
Upgrading one of the electric motors to have a sprocket that works with a gas ATV chain size would not be very easy because the sprocket sizes that fits these motors are very limited. It is usually easier to install an axle sprocket that fits the electric motor's original sprocket than the other way around.

The first step we would take is to figure out the correct gear ratio and sprocket sizes so the electric motor is not overloaded or underloaded and the ATV will travel at the optimal speed for the motor and riding conditions.

350 Watt electric motors can be geared for top speeds of around 15 MPH if used primarily on flat ground. If used for climbing hills or to going through mud or sand then the top speed should be reduced lower than 15 MPH to provide more torque for these type of riding conditions.

Most gas ATV's have chains with large pin to pin distances which makes using them with electric motors difficult in regards to gear ratio, which supports changing the axle sprocket to one that fits the electric motor's original sprocket to obtain the correct gear ratio.

We can help with determining the right size axle sprocket for a 350 watt motor if you could let us know the distance between the ground and the top of the rear tires?
I wouldn't mind changing the axle sprocket instead of the motor sprocket. Inrelation with the speed 15 would be a bit much as teaching him the motor skills of turning and controll I would say ideal max speed would be 10mph. Also what system should I use I have two doners one is a razor mx350 dirt bike or a mongoose m350 scooter. If that even matters?
Version 1-8 MX350 motors are 350 Watts and version 9 and up MX350 motors are 250 Watts.


The MX350 motor has a mounting base which should make it much easier to mount to the ATV frame than the M350 motor would be. So if you have a 350 Watt MX350 motor then that would probably be the best one to use. However if you have a 250 Watt MX350 motor then I would use the 350 Watt M350 motor instead because it is more powerful.

I can check and see what size axle sprocket would work for a 10 MPH top speed. Do you know what the height of the top of the ATV's rear wheel is from the ground?
I do not know the tire height right now when I get off of work in 1.5 hrs I'll be able to relay that information along with original motor sprocket size. So besides the motor watt difference is there any difference in controllers or throttle between the two like I said I have both at my disposal so I could steal parts from one or the other or both.
I would use the same throttle and controller that were used with the motor you choose to install, this way all of these parts are matched and compatible with each other.
The tires are 9.5 inches tall from ground to top of tread. Axle sprocket off the m350 is a 90 tooth and the motor sprocket is an 11 tooth. The area for battery location measure 8"w x 9"L x 7" tall. Would be looking for aproxamitly 1hr run time. What would the charge time be with the 12v 22ah battery's you suggested
I ran a gear ratio calculation with the MX350 motor and the sprockets that you mentioned and got a top speed of 8.67 MPH. Here is the result.


I ran some battery size calculation and found that if the ATV will be used on flat ground with some hills then a battery pack made from two 12V 15Ah batteries will provide a little under an hour of ride time, and a battery pack made with two 12V 22Ah batteries will provide around 1-1/2 hour ride time. These ride times will be a little longer if the ATV is driven only on flat ground or at less than full throttle.


Recharging batteries slowly increases their lifespan so we recommend a slow charge when possible however we sell battery charger that can recharge them slowly or quickly. A slow charge is in the 5 to 6 hour range, and a fast charge is in the 2-3 hour range. These charge times apply to both 15Ah and 22Ah batteries.

Please let us know if you have any questions.

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