There should be a click when you turn on the ignition (from the solenoid). When it does open what revs are you doing > 7000 ? Operating randomly sounds like possibly a bad connection in the wiring somewhere. I think it senses the rpm from the tacho so check all the connections on that as well as the control box. If it works even randomly then at least it sounds as if the valve itself isn't stuck (which has been known apparently).
"Do not adjust your mind, there is a fault in the reality" 1957 175 Sport
Thanks for the help, I've checked over all the connectors and checked all the cables and valve open but still no luck.
I have found that when i turn the ignition two clicks, a strong pull open and then a gentle click back but once warmed up and running nothing. I tried revving it in neutral and it only opens when it red lines so 13-14000rpm??
I think i will try all the connectors again but to work seems more like CDI or not enough power somewhere?
Does anyone have a spare cdi i could borrow to test or should i get onto the phone to uncle Bob to see what hes got?