- Tue Nov 13, 2012 11:40 am
#19473
Just some additional points. Pwayman suggest 1/8-1/4 turn and I would agree this is enough and my suggestion of up to a half turn probably is not required but will do no harm either.. Thanks also for finding the stiction definition. If the head nuts/bolts are loose, then as said, you can just re-torque them with out the turn back....but sometimes they can seem tight and don't move with the correct applied torque, but in reality they are under tightened, hence the need for the small back turn to free them up, just in case they are sticking. Feel assured though that even half a turn will not move the head or any other fastening at all. The last part of tightening a stud or bolt as you will know, is used to stretch it within its elastic state which maintains the joint pressure. By slightly undoing the nut, the stretch is reduced but the two faces held together do not move apart (unless clamping something like rubber)..... As for Dennis's question, re: head tightening...I also can't remember seeing that instruction in the bike's User Manual either, but I think I can remember seeing that at the "First Dealer Service" that head tightening would be carried out?....... In the Bullet manual, it states: "The cylinder head and base nuts should be checked again for tightness after the engine has been run long enough to get it thoroughly warm"....the reason being is that all gaskets become squashed and continue to become even more squashed as time passes especially under the influence of heat, this includes the paper gasket on the cylinder base(often covered in gasket goo)and even annealed solid copper head gaskets. The squashing releases some head bolt pressure and could allow gas leakage to occur. Eventually, further compaction of the gasket stops and no more tightening should be required..... The reason that modern engines don't require a re-torque of the head is because the design of them has allowed an "overkill" in the strength of the bolts/studs to fully compress the gasket way beyond any further possible compression whereas old engines never had the over engineered strength to do this, let alone having enough strength to seal the head with 100% reliability after any amount of tightening.
