what are the differences between the 300R and the 250R top ends?

[Tyler 54]

I just got a top end in a parts lot and I'm trying to figure out what it is.

It has six head bolts. Any help is greatly appreciated!!

[ATCWRENCH]

the 300R jug and head are real blocky looking with seven head studs. the standard aircooled 250R jug and head are really round looking and only have six head studs.

[Lomax]

Air fins on the 300 stand straight up[ on the head where the 250 air fins are slanted along the head.