MY1020 48v 1200 watt specifications

I just built a minibike its great fun but i cant drive it on the street so i decided to build an electric bike. the motor i was going to use was the MY1020 36v 1000 watt motor i did all the math for the max efficiency rpm@36v and calculating the gear ratio that would result in the best efficiency and still maintain reasonable speed, 10:1 with 26'' wheels at 25 mph putting out 570 watts on flat ground and about 15 mph on a 10% grade putting out about 1600 watts. I go to ebay to buy it and its sold out and they wont have more for 2 months, so i bought the 48v 1200 watt MY1020 model, i needed the specifications for that model so i e-mailed unitemotor and they told me that the motor is no longer in production and the specs are not available. Does anyone have the detailed specs for this motor? things like no load speed no load current torque at rated load, all the information provided was "48v 1200w@3200rpm 32A" not enough to calculate the peak efficiency speed. If anyone needs the 36v 1000 watt models detailed specs i got them from unitemotor http://www.freewebs.com/jakhole/MY1020G1000W.doc.

I searched through the forum and found the info http://www.cn-dcmotor.com/productShows.asp?ArticleID=277

I calculated the max efficiency at 48 volts to be 3617 rpm which is 664.86 watts which will give me about 26 mph on a mountain bike, so i guess ill just gear it so the motor is spinning at 3617 rpm while moving at 26 mph. sounds good?

Save Yourself Some Effort!

I own both of those motors and have full detailed spreadsheets for them. Here's the spreadsheet for the 1200 Watt Unite while using a 5 speed hub and low aerodynamic figures like on my bike. You will need to modify the aerodynamic values for your bike. If you want a one speed you need to just delete the other gears. (stick to the green cells for editing values)

You need to convert it from Microsoft "Works" to something that you can use. I think Microsoft Office can convert it to an .xls Excel file.

http://www.gokartnminibikeparts.com/split_racing_sprockets.htm

I would think that with gears you should be able to get to about 35 mph and without gears you're probably about right ending up with about 26 mph. (without gears you have to worry about being able to climb the hills)

dirty_d said:

I calculated the max efficiency at 48 volts to be 3617 rpm which is 664.86 watts which will give me about 26 mph on a mountain bike, so i guess ill just gear it so the motor is spinning at 3617 rpm while moving at 26 mph. sounds good?

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Sounds good.

I like somebody who does his homework first. You should be very close in real life.

i was just going to put a 65 tooth freewheel on the rear hub and make a jackshaft assembly on the motor mount to get the 10.5:1 ratio id rather use a 115 tooth #25 sprocket but the only one i could find was from SDP/SI and its $60.00. with this motor i could get to 32 mph at the rated load but at anything over 0% grade and the motor would overheat so i just decided to sacrifice a few mph and keep it simple with one gear and have it underloaded on flat ground for the peak efficiency and when going up hills it stays at or just slightly above the rated load. does this motor have a flat mount in the side of the motor i cant see it in this picture it looks edited, http://tncscooters.com/product.php?sku=106170. also has anyone ever tried to mount a rear mountain bike wheel on the front fork? it looks like theres some extra nuts on it that would make it less wide and without the big cluster of gears with jsut the 65 tooth freewheel is there any way? that seems like the easiest way to be able to pedal and use the motor at the same time having the motor power the front wheel id have to hack something up on the rear wheel to have 2 freewheels if i wanted to pedal and power the rear wheel.

Since you're going to use a transacle anyway, whynot make it the freewheel and mount it all on the rear? a MB rear hub won't fit in a normal fork, and 1200 watts of power would likely rip its self out of the front fork. Its the same problem the big power front hub motor guys are running into.

i cant think of any easy way to have 2 freewheels on the rear hub all i can think of is having a piece machined that screws onto the hub and then has the same threads as on the hub except longer so that you can screw on the large 65 tooth freewheel for the motor and then a small freewheel on after it for pedaling, any ideas would he helpful. if i cant come up with something reasonable ill just go motor only for now.

I have heard that some bottom-bracket cups are the same thread:

Warning

Transaxles can be a major pain in the ass. I'm on Version 5.0 on mine and I'm hoping that I finally have gotten it right. If you try to use ordinary bicycle components like a hub for your transaxle you have to be very concerned about doing it right.

Go carts use a #35 chain and that's bigger and better than the #25 chain that most scooters use. You can go up to 114 on the go cart chain on the rear and with a 13 tooth on the front you get a speed / hill climbing profile like the chart below.

i wasnt going to do anything to the existing bicycle hub except take the existing multi-speed freewheel off and put a freewheel and a 65 tooth #25 sprocket on from electricscooterparts.com i cant really do any welding since its aluminum all i have is an ac/dc arc welder. all i can think of is to get a pipe of the same freewheel threads weld it to a round plate and somehow attach the plate to the spokes on the other side of the hub and screw the freewheel onto that, this just sems like a bad idea though. I dont know what you mean by the bottom bracket.

I have that exact motor and also the 1000 Watt which is the one I'm now running. They both work. Unfortunately you can't go directly from the motor to the rear wheel with a 65 tooth sprocket. You would be better off with at least a 90 tooth sprocket. The need for a separate axle (what I call the transaxle) is something you should avoid if at all possible.

My advice is to use the go cart sprockets because they use the #35 chain and have a big selection to pick from, but the combination of 11 tooth on the motor and 90 on the rear wheel is okay using a #25 scooter chain. (it's a little bit "tall" of a gear, but you could live with it)

http://www.electricscooterparts.com/sprockets.html

yea i know im making a jackshaft on the motor mount that will make the overall ratio 10.5:1 which puts me at the peak efficiency only about 600 watts but enough for 25 mph.

dirty_d said:

I dont know what you mean by the bottom bracket.

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The bearings and cups for the crank & pedals are housed in the bottom-bracket. A local bike shop (LBS) should have them in stock. Some shops may keep the threaded plugs that ship with bare frames, they might sell you a plug for a buck.

i got the motor today in the mail, there are only 2 very small threaded holes on each end to mount it to something it doesnt seem strong enough should i buy longer bolts that go through the motor that hold the 2 ends on and use those 2 holes as well to mount it to something?

dirty_d said:

i got the motor today in the mail, there are only 2 very small threaded holes on each end to mount it to something it doesnt seem strong enough should i buy longer bolts that go through the motor that hold the 2 ends on and use those 2 holes as well to mount it to something?

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Mine are mounted with those bolts. They are okay. Just be sure that the mounts are strong enough to hold the bolts without breaking and you will be fine. These motors only put out 1-2 hp so they aren't that strong. A typical 50cc motor puts out 4-5 hp and they use bolts not much bigger. Relax.