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2008 Meiduo MD50QT-4 Electric Conversion

I'm converting a 2008 Meiduo Md50QT-4 50cc gas scooter to electric. It's about 200 pounds and I would like it to go 60km/h with a full sized adult on it. These are the specs for the newer version:

I've built an electric skateboard and restored a few gas mopeds but have never built done something like this, so don't know if it's possible.

I was thinking this kit might be a good start:

Any advice helps! Thanks!

Obtaining 60km/h (37 MPH) is possible with the 48 Volt 1600 Watt brushless motor, however, only under optimal conditions such as a perfectly flat or downhill road with no wind or a tailwind. A better top speed to gear the 48 Volt 1600 Watt motor for is around 30 MPH. The 60 Volt 2000 Watt motor is more capable of obtaining 60km/h under normal riding conditions. We have the same kit available with a 60 Volt 2000 motor on this page: 


The most important part of the conversion is getting the gear ratio and wheel sprocket size right so the motor can operate at its optimal RPM during top speed. We have a calculator for determining the wheel sprocket size on our Top Speed and Gear Ratio Calculator page. 

If you would like help choosing the right wheel sprocket size for one of these kits then please let us know the outside diameter of the rear tire and we will be able to run some gear ratio calculations to determine the optimal sprocket size.

Thanks for the reply!

That's great news. I wasn't able to check the current sprocket size this weekend but will hopefully get to it sometime this week and report back. Is it a good idea to buy a new sprocket or can I use the existing one?

The tire itself is a 120/70-12 which looks to be 18.61 inches in diameter.

What is the estimated range on the two kits quoted above?

Thanks again for all the help I really appreciate it!

I ran a gear ratio and top speed calculation for the 60V 2000W motor and found that an 84 tooth wheel sprocket would be needed. The original wheel sprocket is likely to be much smaller than 84 teeth so a new one would be needed. Since the wheel sprocket needs to have so many teeth I would use #35 chain instead of #41/#420 chain to keep the sprocket size down. 8mm chain could also be used for an even smaller sprocket, although #35 chain is larger than 8mm chain and will have a longer service life. The wheel sprocket can be custom made so obtaining it will be no problem at all. 

For the 48V 1600W kit and the 60V 2000W kit, the estimated ride time at continuous full throttle on flat ground is 50 minutes. This is a conservative estimate and the actual ride time will most likely be a little longer though. So for the 48V kit the range should be around 30 miles and for the 60V kit the range should be around 37 miles. 

Please let us know if you have any questions.

Awesome thanks for the info super cool! This thing is going to rip! Does ESP manufacture the sprocket? And can it be added to the kit?

When using a wheel sprocket of this size will I be losing on the acceleration? This will be used in mostly on city streets so would need to have decent enough pickup to keep up with cars and I can sacrifice top speed for pick-up if need be.

We hire an independent machine shop that specializes in sprockets to make our custom sprockets. Since the sprocket will be unique to your scooter we cannot add it to a kit, however, it can be purchased on the same order as the kit so everything will be shipped in the same box. To have the custom sprocket made we will need to know the mounting dimensions of your old sprocket including; center hole ID, number of bolt holes, bolt hole ID, and bolt circle diameter (BCD) of the bolt holes. You will need to have or purchase a digital caliper to obtain these measurements. An inexpensive digital caliper will do the job and should cost under $20. Once you have a digital caliper in hand and the sprocket is removed from the wheel then taking these measurements is fairly easy and we can help with any measuring questions that you may have. 

The larger the wheel sprocket is the slower the top speed will be and the faster the acceleration will be. For a slower top speed and faster acceleration, a larger wheel sprocket could be used such as a 90, 100, or 110 tooth sprocket. 

I've torn down most of the gas engine. I think for the design of this scooter replacing the piston and flywheel with an electric motor will be the easiest conversion. Any other option would require fabrication of a custom swing arm and rear frame. I'm guessing I'll lose power doing this but I'm okay to trade that for ease of conversion. I think the 50cc motor it would be emulating had 2.0hp and a max rpm of 7500.

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