Engine Mounting Tips?


New Member
Local time
4:13 PM
Oct 15, 2023
I'm working with an old 31cc engine from a weed wacker I had in my shed. I'm debating on how and where I should try to mount it, whether in the back or front of the bike. This will be my first build. Any advice for a newbie like me?
You will need a crazy big sprocket and a custom adapter or multiple jackshafts to get a suitable reduction.

A 1 inch roller turning a 26 inch wheel will have a 26 to 1 reduction ratio. 16 to 1 is generally preferred for the forced air cooling engines since they can run high rpm without major heat problems and you still get a decent top speed.

Get into crazy tooth counts for that. A 10 tooth driver would need a 160 tooth driven sprocket or compound reductions. Biggest I have ever seen is a 85 tooth for #35 chain.

The Staton gearboxes use a triple reduction.

Belt drive is an option, but I'm not sure how easy it will be to find a 16 inch pulley, let alone attaching it to the wheel. I have seen some guys use a bike rims but those aren't exactly purpose built for the application. A 20 inch rim should do it, though you'll have to size your belt for the rim rather than the driver, which complicates that.