obriencj

is a pile of bits

The Theoretical Frankentux
a mix of engine parts

The Frankentux is a poorly named idea wherein I take features from a variety of Suzuk 250cc engines and stick them on a TU250’s frame.

From the TU250x
  • frame, seat, fuel tank
  • throttle body, EFI assembly
  • SCEM cylinder, cylinder head
  • exhaust, muffler
  • transmission
  • piston, crank, counterbalance, stator
  • oil pump
From the SP250
  • engine case and covers
  • kickstart shaft
  • engine mount brace
From the ST250XK4
  • kickstart lever
  • drive shaft

As you can see the majority of parts come from the modern TU. The engine case is from the older SP250, because this lets us cleanly omit a starter motor without leaving an empty hole.

The SP250 case has a profile that should fit the TU250x’s cylinder et.al.

The kickstart shaft can come from an SP250 as well, but the lever has to come from the ST250, as does the elongated drive shaft.

This seems to be the only way to get an engine that’s cleanly kickstart-only.

To start with, I can polish up a pair of existing SP250 cases by hand, then install new bearings and o-rings, since I have most of that already.

Finding a new top end will be either difficult or expensive. Possibly both. If I could find a four-valve top end with SCEM plating, I’d go for that over the two-valve from the TU250x. It would mean I’d need the two-into-one exhaust manifold as well, but that’s insignificant compared to finding the cylinder in the first place.