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Motor for a Cafe racer conversion

7203 Views 12 Replies 8 Participants Last post by  Mefodiy
Hi there, I’m doing a cafe racer, and got the engine stolen out of my shed. Then I, WTF, I always wanted to do a fun to ride e-motorcycle! That is the time!

so now I’m starting to look into this new project. First thing I think I need is to define the motor. I need something to go at least around 4500RPM to give a decent speed. Now, if I use a forklift motor,does anyone has any idea about the voltage and load needed,

thanks a lot!
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Hi man, I recently decided to do the same. I bought a cheap(cafe racer looking) 50cc motorcycle and a conversion kit and a battery. To make your life easier I'd recommend buying a conversion kit that comes with a motor. I bought a 72V 8KW conversion kit which should give me around 11-12 horsepower and top speeds of up to 110kmph. Not the fastest but enough for me. I haven't installed the components into the frame yet but I tested the motor and is looking good. Now it's just a matter of putting everything in and figuring out how to wire in the ignition and the fuses. The conversion kit which basically has everything you need including the motor cost me around 2000$ in total. I can send you links to the kits and the batteries if you want.
it can be found easily on
and

here was a conversion in Taiwan of my friend
hope you enjoy!
Hi man, I recently decided to do the same. I bought a cheap(cafe racer looking) 50cc motorcycle and a conversion kit and a battery. To make your life easier I'd recommend buying a conversion kit that comes with a motor. I bought a 72V 8KW conversion kit which should give me around 11-12 horsepower and top speeds of up to 110kmph. Not the fastest but enough for me. I haven't installed the components into the frame yet but I tested the motor and is looking good. Now it's just a matter of putting everything in and figuring out how to wire in the ignition and the fuses. The conversion kit which basically has everything you need including the motor cost me around 2000$ in total. I can send you links to the kits and the batteries if you want.

Thanks a lot! I saw some kits, there are some really good ones. For this built I was thinking about something more aggressive, more fun to drive. First I was thinking on a 25kw motor, but got curious with the idea of making a cheaper and easier one using the series wound DC motor from a forklift.
it can be found easily on
and

here was a conversion in Taiwan of my friend
hope you enjoy!
Thanks lot, I liked a few of the motors on the website.
Hi Gus...This may be too late, but hetes a name for you to look up.
Heinzmann motors, they also supply KTM with their ecross bike motor. These are very compact and theres a 25.kW watercooled one too. Their site gives you extensive data/graphs and drawings. These are supposed to be very high quality and basically service free. Youll also find planetary gearboxes with many ratios.
hope it helps
Heinzmann motors, they also supply KTM with their ecross bike motor. These are very compact and theres a 25.kW watercooled one too. Their site gives you extensive data/graphs and drawings. These are supposed to be very high quality and basically service free. Youll also find planetary gearboxes with many ratios.
That's apparently a PMS 120 in the KTM Enduro Freeride E-XC. KTM has other electric models as well, but they're low-powered kid stuff.
Heinzmann
There are many ratios for their gearboxes, but they all have too much reduction: the least reduction listed is 4:1.
Hi Gus...This may be too late, but hetes a name for you to look up.
Heinzmann motors, they also supply KTM with their ecross bike motor. These are very compact and theres a 25.kW watercooled one too. Their site gives you extensive data/graphs and drawings. These are supposed to be very high quality and basically service free. Youll also find planetary gearboxes with many ratios.
hope it helps
Thanks, I'm gonna check that.
That's apparently a PMS 120 in the KTM Enduro Freeride E-XC. KTM has other electric models as well, but they're low-powered kid stuff.
Heinzmann
There are many ratios for their gearboxes, but they all have too much reduction: the least reduction listed is 4:1.
and the PMS120 rated at only 8kw ...
On endless-sphere lots of the dirtbike builds are done using the QS138V3 (the one with a 1:2.4 gearbox). It's rated for 3kw but it's way under-rated. People are having good results at 15+kw.
Go DIY as much as you can. This sounds like it is your first build. The more you build yourself the more you learn. There's always people like me around that have many builds under there belt that will help you.

While the implementation isn't identical to yours, go see my Zap build in my signature. You'll get lots of ideas from that. I'm not fond of EV kits. Where's the adventure and engineering and creativity in them? You are basicly a monkey following directions. Full on DIY...there's always something new to learn! The Zap took me miles beyond anything I ever did before in every way. It was a great build and the challenges to overcome were many. What I have learned from it will get used in my XM3500 build which will be much more powerful. I encourage you to avoid kits.

For my uses. I have completed 4 scooter builds. 2 were stand-up scooters and 2 were step through like the Zap. I have an e-bike build based on an A2B that is partly done. It's slow moving as I like scooters a lot more. Almost all the mechanical details are worked out and it's waiting for the outrunner, controller, battery and electrical work to commence. I have contributed parts and time for at least 6 EV's for freinds. I always recommend they do as much of the work and design themselves as they can possibly handle.
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On endless-sphere lots of the dirtbike builds are done using the QS138V3 (the one with a 1:2.4 gearbox). It's rated for 3kw but it's way under-rated. People are having good results at 15+kw.
ES is a great source for ideas and there are lots of smart people on there. However, I post here and NOT there. Waaaay too many control freaks, know it alls, arrogant jerks and trolls on ES! The moderators do nothing to stop them either!!! I refuse to post on ES.

The QS138v3 will be plenty strong for your bike, but it's not the only option. I'm not fond of inrunners. The are heavy for the amount of power you get from them. For the same wattage, outrunners cost a lot less, are lighter and more power dense. If I am building a mid-drive EV, it's using an outrunner. I never recommend inrunners when an outrunner can do the same job.

I always recommend mid-drive. My Zap scooter uses a very special 6 phase hub motor so I relented and did a hub motor build. At least that QS is a mid-drive. :)
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