Shown left is the first ball bearing version.

Sizes .36

Fox Combat Special on boost port

Full fin diameter on the crankcase casting
Full, as cast head diameter, unmachined OD.

Bead Blast finish

Small rectangular exhaust flange
no mounting for muffler

Second Bushing Version.

Sizes .36 and .40

Boost port enlarged

Full fin diameter on the crankcase casting

Full, as cast head diameter,
2 grooves machined on head

Tumbled polished finish

Butterfly throttle barrel

Narrow exhaust flange, hole spacing 0.937"

Now we loose track.
There may be models not shown
before and after this one.

Ball bearing version shown.

Sizes .40 and .45

Bump boost port changed to full bypass port.

Fin diameter on the crankcase and head casting machined.

Round throttle barrel

Muffler hole spacing------"

There may be models not shown
before and after this one.

Fin diameter on the crankcase fins and head machined.

There may be models not shown
before and after this one.

Ball bearing version shown.

Size .40

Round venturi

Head band and machined.

Wide exhaust flange, hole spacing 1.100"

FOX 7

Name bar on boost port lengthened.

Front Schnuerle port bypass enlarged.