Topic: CB750 cylinder head torque setting question - 6mm bolts

[Eydugstr]

Is there a set torque value for the two 6mm bolts (the long one & short one in the center of the head, by the cam chain tunnel)? 

[Cabilao]

Maybe this helps

http://www.salocal.com/sohc/tech/torquetable.htm

cheers
Uwe

[PeWe]

Really easy to strip those threads. I torqued 12Nm last time. I guess 10Nm will be OK.
http://www.convertunits.com/from/ft+lb/to/N+m/

[madmtnmotors]

I usually hit 6mm bolts with 6 or 7 ft-lbs.

8 ft-lbs on a 6mm bolt into aluminum threads makes me queasy...     

[mystic_1]

I don't even "torque" those, per-se.  For stock screws I just use a screwdriver and put them down hand-tight, which I'm betting I'm getting at least 5 ft lb on.

For allen head repalcements I  use an allen bit on either a screwdriver handle, or my smallest 1/4"socket handle turning the thing with just a thumb and one or two fingers.

You don't need to go crazy on these particular screws, nor on most of the others which were 6mm JIS screws from the factory.

mystic_1

[Dino]

Manual spec says 9 ft lbs.

[HondaMan]

If the bolts are OEM with a little "8*" in their center, use 100=110 in-lbs. If they don't have the little insignia, use 90-100 in-lbs.
Those are old JIS-spec style bolt markings.

[PeWe]

I think the manual specify high torque on all 6mm bolts.
I have been very worried everytime I have torqued almost 9 ft lbs (12Nm). Helicoil or other thread insert is needed. I have helicoils in both mentioned threads in the cylinder. One of the bolts were broken during some years. Fixed it at last repair/restore/upgrade whene I could make longer threads and helicoil.

Same with cam tower bolts. I torqued 7.4 ft lbs (10Nm) last time despite helicoils, time-sert and one Big-sert (2:nd repair) when a helicoil stripped up thru the aluminum, cam stud.
I was worried when torquing all the 6mm bolts in crank cases last time, 12Nm (8.8 ft lbs)

Very important to use a correct torque wrench. I might have used a bad wrench earlier and tourqed too much.

Higher temperature might help thread failure too...?
One additional worry.....
I guess that a not perfectly flat head + cylinder will cause a bending cam into the cam towers too.
My last re-tourque of head nuts might have indicated not perfectly flat surfaces when the inner nuts on exhaust side could be torqued more (1/4 turn), the other not. (~21ft lbs) 3:rd time since head mount. 2:nd cam change + thread repair of known bad thread of cam stud.
I do not need to pull engine for this kind of job.