What is the correct ring gap? what is the jug and head bolts to be torqued

SOURCE: torque settings for the head bolts on a 1984 xc 125 husky

The stud is 8mm with 1.25 thread. the torque, according to the service manual, is 19.6 to 21.6 Nm or 2.0 to 2.2 Kgm or 14.5 to 15.9 lb/ft.. It all depends on your favorite language.

Please take a moment to rate this answer. Thanks silverfernwe!

SOURCE: head bolt torque specs and whether any sealer used

torque those bolts in a cross pattern in 5 lb increments to 40 lbs. carefully, dont forget to oil the bolts first. No sealer is used

SOURCE: torque specs.

Check manuals here:
http://en.wikipedia.org/wiki/Yamaha_XZ_550#Service_Manuals

SOURCE: im putting my 05 yz 125 top end back together my

G'day. The torque specs for the 8mm head bolts is 18ft/lbs.the jug?(cylinder or barrell) is just tightened down even & firm, as there is no acess for a torque wrench.
OK. other things to note.
Clean the cylinder first in solvent(kero or fuel).Then in warm soapy water in a bucket. Dry-(compressed air is best for this-wear eye protection).once dry lubricate all power valves with oil.
Using a clean white rag-soak the end in your 2 stroke oil & wipe the inside of the cylinder surface untill the rag comes back clean(you will need to do it a couple of times-turn the rag over & do it again).Lube the new piston just before assembly-Also pour a little oil down the main bearing oil holes & over the big end too.
Other things to be sure of are-
Piston on the right way round-arrow to the exhaust.
Rings right way up. Some 2stroke dirtbike rings will only go one way up.Look CLOSELY at the ring ends-on the upper or lower surface there may be an etched dot or "T" or "N" or other marking. the mark goes facing up(on both rings unless single ring piston).
rings positioned with end gaps over the locating pins(the ring grooves have a pin in them to stop the ring turning)
Piston pin clips in correctly.
Powervalve moves freely.
Again-watch when you fit the cylinder-it can be tricky to keep the ring end gaps over the locating pins as you feed the cylinder over the piston.
Hope this all helps
Regards(done this a thousand times)Andrew Porrelli