mounting engine at an angle?

mevergreen

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Aug 1, 2017
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I'm planning on setting out to motorize a bike with a 4 stroke engine, but have run into a bit of a problem. I'm very short (5'0" to be exact) and therefore bikes that I can comfortably ride and get myself on and off without difficulty have frames smaller than a standard frame intended for adults. While bikes with smaller frames are more suited for me, they also have less available space in the frame to house an engine.

This feels like a silly question to ask, but is it necessary to mount the engine upright within the frame? Many of the bikes I've considered building from don't have enough space in the frame to mount the engine upright, but could at an angle.
 


bakaneko

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Nov 16, 2015
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1,311
i am a short rider too. it is fine to mount at a small angle (<10 degree). I have my HS-142F on a 5-7 degree tilt on two dimensions so it will fit in a smaller mountain bike frame. you can also remove the muffler cover and air filter cover to save a lot of space. You will need to mount the filter in a different way (not a big deal). You can also file or cut down the choke level and oil intake cap to a nub (my choke level is a nub and oil intake cap has no grips just the surface). You can also remove the throttle guide and make your own or just secure the throttle tube to the frame. No big deal to do this stuff

take a look at the pictures in this thread. you can clearly see on two dimensions that my engine is not flat. note, these are older pictures so the cap and choke level might not be nubs yet.

https://motoredbikes.com/threads/new-4-stroke-49cc-huasheng-142f-build.47115/
 

butre

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Dec 2, 2013
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2,502
you can mount a 4 stroke pretty much however you want so long as the cylinder is pointing vaguely up or horizontal, only needing to adjust oil levels and making sure the carb is at least mostly level. you may need to modify the flinger depending on which direction you're trying to mount it, but that's easy stuff. look at people converting vertical shaft motors for go karts. a 2 stroke is even more forgiving. there's a guy on one of the Facebook groups that has one mounted upside down on a recumbent to drive the front wheel, and as far as I know it works fine.
 

butre

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Dec 2, 2013
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2,502
you can also get a normal larger frame and a lay back seatpost, those make it easier to get on and off. or you could put smaller wheels on a larger frame. I have a 28 inch inseam and no trouble getting on my skyhawk frame with a 24 inch wheel in the rear
 

KCvale

Motorized Bicycle Vendor
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Apr 18, 2010
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3,518
I'm very short (5'0" to be exact) and therefore bikes that I can comfortably ride and get myself on and off without difficulty have frames smaller than a standard frame intended for adults.
I recommend you go with an electric shifter on a small frame.



Or maybe try a Recumbent Trike.



I have built a few MB's for the 'Vertically Challenged' and in fact have an input for in-seem and weight on my contact form for a build.

The more I know from the start about the rider, the better I can pick the right build for them.
 
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