When to re torque a cylinder head

+1, Angus! Archy, you'll get a lot of argument about this, but those of us who've messed with the XS650 for a few decades and have assembled a few motors tend to have pretty clear consensus on the matter of torque checks, and Angus has summed that up nicely. When I put one of these motors together I let it sit cold overnight and recheck torque. I've had 'em give up as much as 6 footpounds from settling on dowels, gasket compression, etc. If a lot of pressure was lost, I give the motor another round of sitting and tweaking. My preference (and that's all it is) is to recheck torque after the first full heating-cooling cycle. I take a fresh motor for a 10 mile ride after as little idling as possible, let it cool, and reinspect, then check again after 100 miles or so.
 
I like that schedule better than say re-torquing them until they keep the torque, because they won't keep the torque, in my experience. I think the gaskets will slowly compress between tightenings, determining the torque, and stabilizing at some point. I would say don't re-torque at all, except that I remember a Technical Bulletin that advised doing it to stop leaks in new-ish engines. Also, I've noticed that anything over the spec torque just goes into twisting the studs and they spring back. Someone warned that too much over the spec torque may pull up around the studs and cause the surface for the base gasket to become uneven.
 
With all due respect, xj, your experience doesn't correspond to mine when it comes to achieving stable pressures. A couple of factors could be responsible. First off I lube the threads with assembly lube and run the fasteners down to late spec. torque. IMO if threads are left dry the torque wrench will often indicate no more than the sticking point of the threads as opposed to giving an indication of how much pressure is being applied by the fastener. I also use only Vesrah or custom made copper head gaskets. Athena head gaskets are not made to OE spec, and are ~.017" thicker I have no idea how those behave under pressure.
 
That's my experience with both stock gaskets and what I consider to be good aftermarket gaskets. I realize you have been at this longer than I have, but my experience is my experience and it is consistent so far :)

P.S. Why else re-torque it yearly? The bolts aren't stretching. The nuts aren't turning. The cylinders aren't shrinking. It is the gasket determining the torque in the end.

P.P.S. Lubing the threads -- I started with anti-sieze, progressed to motor oil, Breakfree (used on military weapons and the slickest medium-duty stuff I know of), to clean dry threads with nothing on them. This all with original gaskets. I prefer nothing on them because of the ping on re-torquing that told me the nuts hadn't been turning. A good professional motorcycle mechanic suggested blue locktite, which I didn't feel the need to try... Torque always disappears, especially on the outer four studs. I'm sure my outer four are much less than 27 ft. lbs. now, but there is no problem :) I don't want animosity here anymore. If I was hanging out with anyone here, I'd get them a case of whatever they're having...
 
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