Motorized 20" BMX [ELITE CMNDR]

CrimsonPrince

New Member
Mar 6, 2020
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Hey all, I've got an Elite Bikes CMNDR BMX that I'd love to motorize. I'm willing to try anything save for cutting/modding the frame, so any unique mounting options are viable. I'm considering a friction drive or an in-frame engine, but would appreciate any insight on the idea. Thanks in advance for your time!
 

allen standley

Well-Known Member
Oct 22, 2011
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Bangor, Maine
Hello and Welcome!
20" BMX doesn't allow much space for a 2 stroke in frame. Maybe it will fit? If you got a pic to post with a yard stick propped on the pedal crank housing and focused on the top cross bar showing seat tube length... I think you need a minimum 15". Not too sure though. I never put an engine on a 20" bike before maybe someone who has can chime in. Good Luck to you and be careful, safety first>
 

CrimsonPrince

New Member
Mar 6, 2020
29
8
3
24
Hello and Welcome!
20" BMX doesn't allow much space for a 2 stroke in frame. Maybe it will fit? If you got a pic to post with a yard stick propped on the pedal crank housing and focused on the top cross bar showing seat tube length... I think you need a minimum 15". Not too sure though. I never put an engine on a 20" bike before maybe someone who has can chime in. Good Luck to you and be careful, safety first>
Thanks for the insight. I measured the dimensions and my frame wont allow a 2 stroke, let alone 4 stroke engine in line. However, I was thinking about rear mounted chain drive or axle drive (leaning toward axle drive due to compactness, but I'm concerned about some of the setups that I've seen, as its mounted by a single bolt with no connection to either of the stays).
Any ideas as to an axle mounted system that is viable for a 20" rear wheel?
 

PeteMcP

Well-Known Member
Jun 27, 2017
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Welcome to the forum.
Motorized 20" BMXers look so cool when done right. And by done right, I mean using the correct components - or if your welding is up to it, by cutting/adapting your frame to accept a motor mount to fit any of the under-slung lay-flat Honda C type Cub engines (or clones) from the 50/70/90/110/125cc range as shown in the accompanying pics. Your call, but I'd go out of my way to avoid mounting any engine up-and-out-back on any bike - just 'cause that kind of set up always looks like a jerry-rigged afterthought to my way of thinking. Hardly has a 'performance' look to it, does it? You and others might have a different opinion.
There are dedicated BMX Cub frames available for such a conversion from the likes of Mad Munk or Kepspeed here in the UK. Everything else needed, from forks, wheels, seats etc. is also stocked. You'd have to search for something similar in the US. I had plans a couple of years back to do one of these using a Lifan 110cc semi-auto engine but then I changed plans and went down the board tracker route instead.
Just search Google for Motorized BMX Cub and you'll find plenty inspirational pics of custom machines. There's thriving scenes for these worldwide - but maybe not in the US?
Kepspeed BMX cub frame.jpg
motorized BMX.jpg
 
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CrimsonPrince

New Member
Mar 6, 2020
29
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M
Welcome to the forum.
Motorized 20" BMXers look so cool when done right. And by done right, I mean using the correct components - or if your welding is up to it, by cutting/adapting your frame to accept a motor mount to fit any of the under-slung lay-flat Honda C type Cub engines (or clones) from the 50/70/90/110/125cc range as shown in the accompanying pics. Your call, but I'd go out of my way to avoid mounting any engine up-and-out-back on any bike - just 'cause that kind of set up always looks like a jerry-rigged afterthought to my way of thinking. Hardly has a 'performance' look to it, does it? You and others might have a different opinion.
There are dedicated BMX Cub frames available for such a conversion from the likes of Mad Munk or Kepspeed here in the UK. Everything else needed, from forks, wheels, seats etc. is also stocked. You'd have to search for something similar in the US. I had plans a couple of years back to do one of these using a Lifan 110cc semi-auto engine but then I changed plans and went down the board tracker route instead.
Just search Google for Motorized BMX Cub and you'll find plenty inspirational pics of custom machines. There's thriving scenes for these worldwide - but maybe not in the US?
View attachment 103862 View attachment 103863
Much appreciated, Sir. Do you know where I can find frames that are cut out to accommodate an in-line engine?