S 650 serial number?

[special-k]

While digging through some scrap engines. I found a 650 engine with s 650 in the serial number. The rocker cover for the decompressor is missing so that's out as a way to check. Is this a 256 type engine? Looked around online and it seems like it might be a early one. Thanks

 

[special-k]

Looks like I found the answer myself. went and checked the serial number on the race bike engine and it's S650 also. And I know that engine is a 73. So I guess 256 series engines are stamped S650.

 

[TwoManyXS1Bs]

The S650 serial numbers will be found on the 70-73 models.

Mostly applicable to the 70-71 models, the "256" shared moniker relates to the crank, rods, camchain, cam.

The 72 XS2 introduced an electric starter, exhaust valve compression release, and lower 1st gear. Its code number is "306".

The 73 TX650 has some code number "366" parts.