Update...
I had to disconnect the new cable from starter solenoid to coil +ve as as soon as I changed the ignition switch from start to run the engine would die. So it seems this was a wasted effort in cabling.
But the great thing is that having changed the rotor there IS enough spark to start! I don't really understand this. The rotor is just over 18 months old with no evidence of cracking, fatigue or carbon build up.
But evidently it can no longer transmit HT spark from coil to appropriate contact inside the dissy cap. (I'll measure the lengths of the tips on the working and non-working tomorrow to see if that is the cause.)
Tongue hanging out at present as I've just been for a brief test drive round the block a few times:
[:p][:p][:p][:p][:p]
The 45 DCOEs that I've just fitted as part of this work make a huge difference:
[:D][:D][:D][:D][:D]
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ps. The DCOEs have changed the exhaust note and smell considerably. I can still taste it now, bringing all sorts of recollections of being at race tracks in the late 70s and early 80s.
[:)][:)][:)][:)][:)]
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pps. I've just made some adjustments to the Webers and it's even better! I am so amazed at the difference between SUs and DCOEs.
If you own a Sprint I can't recommend this change enough!
[}:)][}:)][}:)][}:)]