"Back them off"? I prefer the term "break them loose". Sure, you turn them in the reverse direction, but only enough to free up the fasteners, and then proceed with tightening to spec. Probably the biggest concern with torquing parts on an aluminum engine is doing it in multiple passes, and not trying to get everyhing tightened up in one swoop. This is a bit trickier on an engine that has already been run in because there are no guarantees that they (the nuts) will all be starting with the same initial torque. Generally, I back off all of the stud nuts just enough to get them to move, and then retorque to 15, 25, and then 30 ft/lbs, being sure to use a cross-tightening pattern. The big thing is to be sure that the nuts actually move when you turn them. If not, you're only twisting the stud which will create problems, either immediately, or in the future.
Also, I never apply scotch, single malt or otherwise, to either myself or the bike during the retorquing procedure. This is due to it's habit of introducing operator error and clouding one's judgement, thus contributing to premature gasket and/or engine failure.
David Szenasy wrote:
A local motorcycle shop told me to back all the bolts off, then re-torque. I was told by a Guzzi owner that if I do that on the old bikes, they will start to leak. What is the best way to go about this? Since putting new cylinder kits on the bike, I torqued the heads by backing each nut off and re-torquing one at a time.