Hi Guys,
I built up a pedal bicycle as a boardie and it's a cool bike, great for bombing down hills as a gravity racer, but eventually I have to pedal and pedaling a boardie for a tall guy like me is difficult. The pedal bike is a 110mm Sportsman Flyer frame with a single speed coaster brake hub. These frames are built from .090" wall tubing and are perfect for the smaller four stroke engines.
Here is the starting point. Last day as pedal bike and time for some four stroke power!
Sportsman 80 by Sportsman Flyer, on Flickr
Here's the engine I am using. This is a Harbor Freight 79cc four stroke. As shown here I have already stripped down all the unnecessary components like stock gas tank, intake, carb, and exhaust. I have added a custom intake and exhaust manifold and 19mm Mikuni carb. I also removed the internal engine governor, plugged the governor holes left in the case, and trimmed off a piece of casting I didn't need. Oh, I also stuffed in a nice fat cam from AGK and some stiffer valve springs.
Sportsman 80 by Sportsman Flyer, on Flickr
On this side of the engine I had to drill through the side cover casting to add the oil fill point cap. Drill through, tap 1/2" NPT, then add a 1/2" NPT by hose fitting and a brass hose cap. Intake and exhaust components are all tig welded stainless steel with laser cut 1/4" stainless flanges.
Sportsman 80 by Sportsman Flyer, on Flickr
I built up a pedal bicycle as a boardie and it's a cool bike, great for bombing down hills as a gravity racer, but eventually I have to pedal and pedaling a boardie for a tall guy like me is difficult. The pedal bike is a 110mm Sportsman Flyer frame with a single speed coaster brake hub. These frames are built from .090" wall tubing and are perfect for the smaller four stroke engines.
Here is the starting point. Last day as pedal bike and time for some four stroke power!
![](/proxy.php?image=https%3A%2F%2Ffarm4.staticflickr.com%2F3859%2F15004047996_99901806b0_o.jpg&hash=ea61f7348dacce93faa22ec3eadbc9a7)
Here's the engine I am using. This is a Harbor Freight 79cc four stroke. As shown here I have already stripped down all the unnecessary components like stock gas tank, intake, carb, and exhaust. I have added a custom intake and exhaust manifold and 19mm Mikuni carb. I also removed the internal engine governor, plugged the governor holes left in the case, and trimmed off a piece of casting I didn't need. Oh, I also stuffed in a nice fat cam from AGK and some stiffer valve springs.
![](/proxy.php?image=https%3A%2F%2Ffarm4.staticflickr.com%2F3875%2F15023950061_0eac169f9f_o.jpg&hash=918b8904ec65e8212ad523aebd6cc33e)
On this side of the engine I had to drill through the side cover casting to add the oil fill point cap. Drill through, tap 1/2" NPT, then add a 1/2" NPT by hose fitting and a brass hose cap. Intake and exhaust components are all tig welded stainless steel with laser cut 1/4" stainless flanges.
![](/proxy.php?image=https%3A%2F%2Ffarm6.staticflickr.com%2F5559%2F15026652912_06f1cf048f_o.jpg&hash=7dcbb93d6660305fa6960f546bd52a2e)