Occasionally the question comes up about which Yamaha KT-100 cases are considered good ones and which are not.
Yamaha has used 3 different methods of manufacturing cases during the life of the KT-100. I call these:

• Sand cast cases (view: back, pto, ignition, and base sides of this case type)
• Permanent mold cases (view: back, pto, ignition, and base sides of this case type)
• Die-cast cases (view: back, pto, ignition, and base sides of this case type)

Sand cast cases are very old... I'd guess them to be circa 1977 or so. Only the first few hundred KT100's that came into the U.S. had sand cast cases. They are generally characterized by a very dull, rough, sandblasted look.

Permanent mold (aka: gravity cast permanent mold) was what all cases were from around 1978 until about 1989 or so (I could be off a year or two). These cases can be (and usually are) fairly shiny, with a bit of an "orange-peel" look to them.

Die-cast cases have been the only thing available since around 1989. They have a slick, satin-finish look, and are a bit lighter (in weight) than the earlier cases.

Generally speaking, the permanent mold cases are the most desirable. The material in these cases is denser and quite a bit more stable than sand cast or die cast. (Click here to see a side by side weight comparison: newer die-cast on the left, permanent mold on the right)

Certain die cast cases can be very porous. I've seen some die cast cases that are almost "sponge like".
Be very careful with pressure die cast cases... they are simply not very strong. Stamping a name or number in the top of a case can be enough to permanently distort a case. They are very soft, regardless of how they might look. Make certain that the bottom of the case is very flat, and that the top surface of your motor mount plate or adapter is also very flat. Bolting one of these newer cases to something that is NOT flat will result in some fairly significant distortion.