| | | DIY Home Built Motorized Bicycle (non kit) Post all about your home built rides here. Weedwacker motors, lawn mower engines ect. This area is for non kit builds | 31cc ryobi bmx, chain drive Discussion at Motorized Bicycle Engine Kit Forum in the DIY Home Built Motorized Bicycle (non kit) forum. hey, im thirteen and have been building things for as long as i can remember, this time i wanted to ...  | 
10-14-2009, 07:33 AM
|  | Motorized Bicycle Member | | Join Date: Oct 2009 Location: australia
Posts: 20
| | 31cc ryobi bmx, chain drive hey, im thirteen and have been building things for as long as i can remember, this time i wanted to build a motorised bike, i was originaly going to use a homelite chainsaw but when i couldnt get it to start up after a rebuild i knew i was time to get a new engine, i went trashpicking and found a 31cc ryobi lawn hornet whipper snipper that had a clutch on it, i recently bought a bunch of clutches so if it wares out i can just pop another one on. the drive shaft setup is based around a 17.5 to 1 gear ratio and does the job perfectly, it doesnt bogg out and the clutch engages at a resionable time, on the engine there is a 11 tooth that goes to a 35 tooth that comes across the jacksaft to another 11 tooth to a 72 tooth go kart sprocket on the back wheel, i highly recommend using a 17.5 to 1 gear ratio for any small engine like this because it has a good all round torque and speed range, it will do 45kmh easily on flat ground and can get up most hills.
this was a great project to do and was very rewarding at the end of it, the bike is fuel efficient , fast and fun!
if you want to see this thing riding, go to youtube and search "Cchange4us", click on my channel and follow your instinct
Last edited by TorqinDirty : 10-15-2009 at 03:47 AM.
Reason: i made a mistake
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10-14-2009, 01:29 PM
| | Motorized Bicycle Member | | Join Date: Sep 2009 Location: modesto
Posts: 34
| | Re: 31cc ryobi bmx, chain drive Awesome build man, I have a ryobi 66cc 4 stroke weed eater I want to put on a bicycle, now you've got me thinking of tinkering in the garage lol  | 
10-14-2009, 01:50 PM
|  | Motorized Bicycle Elite Member | | Join Date: Aug 2009 Location: ontario
Posts: 112
| | Re: 31cc ryobi bmx, chain drive Thats pretty cool , i checked out the video , seems to run pretty good .
I like the way the motor fits nicely into that small space in the frame .
It would be nice if you could get the pedals back on , but it doesn,t look like thers much room left on the right side . Nice job with the chain drive . | 
10-14-2009, 01:53 PM
|  | Moderator | | Join Date: Jul 2009 Location: Maine
Posts: 1,198
| | Re: 31cc ryobi bmx, chain drive Dang - that's a sweet lil bike man, nice job! | 
10-14-2009, 07:52 PM
|  | Motorized Bicycle Member | | Join Date: Oct 2009 Location: australia
Posts: 20
| | Re: 31cc ryobi bmx, chain drive Quote:
Originally Posted by diceman2004 Thats pretty cool , i checked out the video , seems to run pretty good .
I like the way the motor fits nicely into that small space in the frame .
It would be nice if you could get the pedals back on , but it doesn,t look like thers much room left on the right side . Nice job with the chain drive . |
thanks, pedals were something i wanted to have just incase it broke down but this would mean i would have to have the sprocket on the other side of the rim so whenever the wheel moves the system momes and i didnt really want that | 
10-14-2009, 07:56 PM
|  | Motorized Bicycle Member | | Join Date: Oct 2009 Location: australia
Posts: 20
| | Re: 31cc ryobi bmx, chain drive hey, thanks for your comment, a 66cc 4 stroke would be awsome, i dont recommend doing what i did with the jackshaft though, try a gear box of a scooter, unless you do this to a exeption quality (wich i didnt) you should go with a gear box then to a chain down the back | 
10-14-2009, 10:20 PM
| | Motorized Bicycle Senior Member | | Join Date: Dec 2008 Location: iowa
Posts: 69
| | Re: 31cc ryobi bmx, chain drive good job looks nice and effective
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