Motorcycle Repair: T140 e timing, haynes manual, ferocious beast

Question
Hi my name is Mark and hope you can answer my question.I have T140e 79 model and am about to fit a T120 exhaust camshaft part no 709989 as apposed to the detuned original. My Haynes manual does not give the valve timing in degrees for the 750's only the 650's. Could you give me the best timing degrees for this conversion as I wish to reassemble the motor using a degree wheel. This bike is a dual use machine, used both on the road and track (Classic Bike racing). Thanks in advance for your assistance.

Answer
I would leave the valve timing alone and set as standard, using the markers as on the valve pinions. As you know the inlet cam is a ferocious beast being up to full 'Thruxton' profile, it's copy of the BSA 'Spitfire' profile actually, but we don't let the Small Heath brigade know that! The standard valve timing was originally set for use with a 'Half-Race'cam not unlike the 650, but noise emissions and the fact that the vibes knocked out the early design mains meant a change to the much softer cam normally in use. Remember though you will have to play around with the carbs after fitment.
Regards
Brian