4 stroke on a kids BMX? Hell yeah!

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I saw this BMX laying around in my buddies yard.. "can I have it and put an engine on?" "you can do to this bike whatever you want"
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20" wheels

I used round steel from ace hardware, flattened the ends and drilled a hole for a screw. Then I was able to mount the engine mount over the rear wheel. A twisted piece of flat steel prevents back and forth movement. That one is slotted so I'm able to move things around later on
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This bike has massive steel drop outs so no problem drilling through them.



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Top speed at 6800RPM is 25mph. Hop on, pull start, give it some throttle and go. It feels zippy and easy to move because it's so small.

Just yesterday I replaced the 100t pulley with a 80t pulley.
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my beer holder and GPS speedometer

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I built my own extra long throttle cable out of an old brake cable

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Sidewinder Jerry

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Oh I just said 25, it’s my own limit since I don’t have a rev limiter. You’re right, at exact 6800rpm it is a bit faster. My gps speedometer is accurate, tested.
I also use it as an odometer, trip meter, fuel gauge and run time. Link https://www.amazon.com/dp/B088JVVS1Z/ref=cm_sw_r_cp_api_i_0XJJECVHXRR3MHRQWTJV?_encoding=UTF8&psc=1

Edit: @Sidewinder Jerry Oh and thanks with the tip for the tachometer! I actually use them on my commuter bikes. I hooked one up to this baby bike just to see and test but then removed it. I’ll do my oil changes per miles on this bike, the bike is just for fun. Most parts and the engine I had laying around after upgrading to Grubee on my other bikes
If that's the way you want to do it. Then you'll need to multiply your average miles by the recommended hours then change it when you reach that number. My Robin Subaru is 12 years old I change the oil every 25 hours and clean the air filter every 10 hours.
 

Mike St

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Jun 16, 2008
Messages
747
A little on the cumbersome side. I believe my idea is better.
I use a small 5:1 scooter gearbox and rear mount it to the right side
of the bike using two freewheels. I have already tested this
design and it really works well. The motor is more centered
and the entire combination is light. I'll post pics when I
finish installing the design on a 24 inch bike which I
am doing now. The drive has to be from the right
side because the gearbox reverses the direction of
the motor. But good work!!
 

Nirve

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