On the old Brit. Gannet engines you could get reverse rotation by swapping the pushrods from one valve to the other.

Dennis - as Martin said, you can retime the two camshafts independently only on the ENYA 4S and thereby reverse the rotation.

I have the new timing diagram if you need it.

The SAITO and OS 4S engines have the cams on a common shaft such that they cannot be retimed.

You can fabricate a reverse rotation camshaft if you have access to a machine shop as well as metal treating facilities.

Bob Z.

 If Im not wrong , the Satio Cams are two piece ,  (two lobes ) then assembled and swaged.

 It appears Gilbert Berringer ran a clockwise . 40 on one side of his twi.

 The Guess is , he ordered an unassembled cam from atio and set the lobe seperation opposite .

 Other alternative would be to grind of the swageing , seperate it , reassemble it with opposite seperation and w weld (electrick ) . pref. T.I.G.

 Good old hot rod Know How . ?
 Generally the overlap period is just before T.D.C. for retiming .
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Hot Rod tecnology was to weld and grind lobes. (or British Motorcycles.)
Generally non critical on singles .Cutting the profile with a file , and hand stoneing smooth prior to rehardening wasnt unusual. Though unless the gear wheel was removable , this could give you problems.

SO seeing if you can get an un - pressed Satio Cam , or other if there also two seperate parts
would be the safest way to go.to avoid expensive noises .