B&S 3.5hp belt drive

Hello!

After building a rather successful 2 stroke motorized bicycle I thought I'll try to make something different like a belt driven 4 stroke motorized bicycle. I have got a lawn mower engine which I'll convert to run horizontally, it is a 3.5hp Briggs & Stratton.

I will use an old bicycle frame which is going to be chopped to fit that engine. I want to avoid using a jackshaft so the rear pulley will be a 26" bicycle rim fitted side-by-side to another 26" rim with a thin tyre. I'll try to find a small pulley to fit on engine shaft, 63mm diameter is the smallest I can find. Gear ratio would be 8.87:1, at 5000 rpm it should reach 43.6 mph. I have seen one like this on youtube so I remain optimistic about the gear ratio.

Please comment on my project so that I could work out all the flaws before starting to build.

chainmaker said:

Welcome to the forum, you will enjoy how quiet a belt drive is. I haunt seen a vertical to horizontal conversion. Good luck and welcome to the forum. In Europe you have access to 26 in moped tires which is good. What type of bicycle will you be using?

Click to expand...

I will be using an mtb frame which is now lieing in the basement. It is just a common cheap frame. Basically whole bicycle will be cut into pieces and custom welded in order to fit the engine.

Talking about the clutch, I am planing to use some king of tensioner so that I could manually tension the belt. At the end it should look like the one in this video:
http://youtu.be/P5xs0WMpGF8?t=5m