New Inclined Briggs Motorbicycle concept

[boogerballs]

I've got a new idea for a motor bicycle. I want to take a small (2.5-3.5hp) Briggs and Stratton engine and mount it almost horizontal with the bottom of it mounted on the seat tube.

I plan to have a belt drive with a belt-tensioning clutch. The engine will run to a jackshaft just behind the seat tube, then on to the sheave on the back wheel.

I also plan to take off the air shrouding, trim down the fan blades on the flywheel, shorten the crankshaft at both ends, remove any excess aluminum air directional shrouds on the cylinder and reshape the cylinder as round as I can get it. This is to make it look less of a Briggs as possible.

I took a look and as long as I keep the intake and exhaust to the top of the motor, I don't think I'll have a problem with excessive oil burn. Also, the little oil slinger will dip down into the new, tilted over bottom end and fling the oil just right. I'll probably have to drill and tap a new drain plug and filler plug and figure out some sort of dip stick to check the oil level.

I'll have to use a small Tillotson type carb on a new intake manifold. I'm not sure quite yet what I want to do for the exhaust.

I like the fact that this will get the bulk of the motor as far above the pedals yet still within the frame of the bike. I will use a Schwinn cruiser frame, there's more than enough room.

So what to you guys think? I plan to get started soon.

I'll try to upload an image of my plan soon.

- boogerballs

 

[Nuttsy]

If the only reason you're wanting to do this mounting method is pedal clearance, I get that. My concern would be the oil distribution. These are splash motors and in that orientation, I'd worry if that distribution was even and not starved on the upper (vertically speaking) side of the cyl. Then too the oil sump might not be 'ideal' in that attitude either. I'd compare it to trying to use a vertical shaft engine in a horizontal mount. Hope you've got it all figured.
Plug fouling may be another problem.
At any rate---good luck.

 

[boogerballs]

I'll be doing everything I can to keep the lubrication as similar to a stock motor as possible and realize that this is not ideal for the motor. Also it's not just for pedal clearance but also for looks. A Briggs in it's normal stance looks like nothing else but a Briggs and Stratton. Since I'll be way over the 50cc limit here (illegal in my state), I want it to look like it's not a Briggs. As soon as I can I will try to get the engine running in this configuration and we'll see...

 

[Al.Fisherman]

If you rotate a B&S 4 stroke engine 90 degrees to it's intentional mounting, the engine will either burn up or throw oil all over the place. There is a oil sump and most rods have a splash tap on it.. Ummm need a customized intake manifold.

 

[boogerballs]

I'm kinda hoping for the "throw oil all over the place" one. Since it's bottom edge will be mounted to the seat tube, the incline is not quite 90 degree, more like 75. And the customized intake manifold is already on the list.

- boogerballs

 

[adb140275]

its not gonna get enough lubrication to the top end.

 

[boogerballs]

Why would you say that? It is still going to have the little oil slinger dip down into the oil sump and fling the oil around the crankcase, hitting the tappets and everything else exposed in the crankcase. Since that is the only oiling that happens (no oil pump) I don't see the real problem. The vertical shaft motor is already very similar.

 

[Wheres my dog]

Not a good idea cutting or trimming down the air shroud or blades....

Can you say overheating?

 

[boogerballs]

It's an aircooled motor mounted in a motorbike which won't be running in one spot for very long. The only reason that all those air shrouds were necessary is that the engine is normally revved to it's limits sitting in one spot or moving very slowly (lawnmower, pressure washer, rototiller). This application will be in a bike with airmoving all around it as it's merrily chugging along at 15-30mph. Cooled!

 

[Wheres my dog]

From all my experience....

that airshroud and fan is there for a purpose just like on an air cooled vw!

Not sure a passing by breeze is enough to keep it from overheating or seizing up!

Just my two cents