Not a huge fan of helicoil though can be effective and manageable in a smaller kitted workshop. I always ordered the extra length types ( can be cut to size for blind holes, mostly what we do on Laverda ), bottom tap the blind hole, remove all swarf, chemical clean. My technique, right or wrong, strong ( stud lock ) grade metal adhesive, though not too much, in the expanded thread area, when fitting the helicoil.Wise, Legs. I was able to do one outer one using a Big-Sert - same cause as you, failed Helicoil; but I wouldn't risk it with any of the others.
(Helicoils - "Right shit cakes, them", to quote Keith Nairn. I'm still trying to get my head round 'shit cake'. Must be a Glaswegian thing ...)
As JLO sorted many years ago, the French edition of factory Laverda manual, THE correct torque for non crank case studs, 18lbs/ft and crank case studs at 22-24lbs/ft. English edition had figures that brought many a tear on the cheek... BTW it is always the center cam block non crank studs that go... and almost impossible the repair with motor in the frame...
Have a bit going on lad.... an aside: Have you thought about a car? Your parents worry about you on those dangerous bikes... how many of you heard that in the day, some lads used it as a lever to get a car, they did not want a bike, just the car, and it worked.... j.
