J-MODEL (KZ1100-A2) CAM CAP BOLT TORQUE

FSM cam cap bolt torque spec of 12 ft. lbs. (144 Inch lbs) confirmed with 100% confidence

40 odd years of heat cycles and steel bolts into worn ally threads. I would just ignore torqueing them and just go with a small spanner and "feel" for fear of stripping the journal threads. 

wrote:

40 odd years of heat cycles and steel bolts into worn ally threads. I would just ignore torqueing them and just go with a small spanner and "feel" for fear of stripping the journal threads. 



 

No thread issues since I started using clamps to hold (or force) my cam caps down prior to loosening and installing the bolts.
That being a head with no compromised threads to begin with...

I too have been fooled by the 12ft-lb misprint in the Kawasaki service manual.
After tearing up a coupe of good heads I now torque them to 87in-lb.
 

wrote:

I too have been fooled by the 12ft-lb misprint in the Kawasaki service manual.
After tearing up a coupe of good heads I now torque them to 87in-lb.
 

 

100 in-lbs max

They use 6mm hardened screws.

wrote:

100 in-lbs max

They use 6mm hardened screws.


 

Why employ hardened bolts for an 8 ft. lb. torque application? 

I'd be worried about the potential for valve-spring pressure working bolts loose, especially with high-lift cams.

8 to 10lb max but I never torque them.
Just nip them up by hand and feel with a 10mm spanner.
Apply a whiff of blue loctite if you are uncertain but the valve spring pressure actually helps prevent them from loosening.
 

Soooo, once again we are trapped in the Valley Of What's Best......

Rick H.

wrote:

wrote:

100 in-lbs max

They use 6mm hardened screws.




 

Why employ hardened bolts for an 8 ft. lb. torque application? 

I'd be worried about the potential for valve-spring pressure working bolts loose, especially with high-lift cams.

The screws have a 9 on them correct?  Those are harder and stronger than bolts with a 7 or 4 on them.  The strength of the screw doesn't mean they stretch less under any given torque, it just means they can take more stretch (stress) before breaking.  The threads in the head typically pull out of the head before the screws break though.

wrote:

wrote:

I too have been fooled by the 12ft-lb misprint in the Kawasaki service manual.
After tearing up a coupe of good heads I now torque them to 87in-lb.

Wanted to chime in too but you were so sure of your job and it was too late at that point. Have went around 65-70 inch lbs for years (after reading of problems) then giving a little more by hand so probably around 80-85. Hell I Was so worried about it I heli coiled all 16 holes before sending it in for reworking but will admit that was a little much.

 

 

If you got them to 12ft/lb, you were extremely fortunate and lucky. The fact the bolts may or may not be hardened bolts really doesn't matter. The aluminum threads will strip. Some 6mm bolts are OK to torque to 12ft/lb, but must be dry threads at the least. An oiled thread such as these can't be torqued to 12ft/lb ever. 
I've stripped too many even using the more common 6mm bolt spec of 5ft/lb or 60 in/lb than I care to remember, but mine were off/on on the KZ650 many, many times. The exhaust side will always strip, rarely the intake cam for some reason. Trust me, they will never work loose ever even if you choose to error on the light side of specs for a 6mm bolt.