I dont own one as such but I helped with the building of a 5hp briggs junior drag kart motor.
About the only original bit left on it was the sticker on thwe cowling. had the following done to it...
-used the points and had a high voltage transformer type ignition coil
-Shaved the head as far as we could without the valves running into the head and polished the chamber
- ran a crankshaft from a much bigger engine (i honestly cant remember what) had to grinf the inside of the crankcae out and tig new covers over the sides to compensate for the stroke.
- Ran a much larger piston (pretty sure it was from the same engine as the crank) had to have a custom billet conrod made
- Big mikuni dirt bike carb
- Large (for engine size) exhaust with a little hotdog in it.
Now power figures may never be known, I stopped talking to the guy at the end of the build due to personal differences, however during testing the thing was absolutely off the chain.
