may have the problem solved ??
Again he came back in about 5 to 10 minutes, bike dead again.
Petrol in float bowl was almost oil like!
The breather tube on idle screw side was connected to a nipple on to of gear box.
When we got bike, there was a tube in same place, but was just a bit too short. So I replaced with longer tube and connected them up.
Thinking crap from here is feeding up the breather tube, back into the bowl, blocking jets, cutting out bike.
He's back out on bike, with no tubes connected for now.
Feed back on this thought please