08 yz 450 Head Bolts

[FEAR OF FLYING]

Need info on proper torque specs to tighten bolts on head.

Edited October 25, 2009 by FEAR OF FLYING

[grayracer513]

Here's the proper info on the whole bike:

http://www.yamaha-motor-europe.com/community/service/manuals.jsp

Torquing the head bolts is a little complicated. It's a process called angle torquing, and is intended to provide uniform torque in spite of the typical influences of thread friction, etc.

A clean, dry head gasket (use no additional coating, it has its own) is placed on the cylinder, and the head positioned on it. Apply anti-sieze thread lube to the bolt threads and torque them uniformly to 22 ft/lb in the following pattern: left rear, right front, left front, right rear. This will pre-crush the gasket.

Loosen all the head bolts, then retorque them to 14 ft/lb. in the same pattern.

Then, mark each bolt and the head as to it's current position, and following the same pattern, turn each one 90 degrees at a time until they have been turned 180 degrees from where they were at 14 ft/lb.

[FEAR OF FLYING]

Thanks GrayRacer,

We went straight from 22ft/lb to the 180 setting. We will go back and redo torque to 14ft/lb and then set with the 180 final turn at the same torque. Also we started the bike up at the 22ft/lb , 180 setting and wonder if this would cause any damage to the bike ?

[grayracer513]

If you went 180 beyond 22 ft/lb, the head is over torqued, and the head surface, either surface of the cylinder, or the cylinder mounting surface on the crankcase could conceivably be damaged (distorted) by that. The only really safe thing to do at this point is to pull the top end off, check everything, and reassembling if or once it's OK. Loosening the bolts and doing the torque over from 14 may work, but may not.

[FEAR OF FLYING]

Okay we will do this and check everything and reassemble. Hopefully there is no damage. I will get back to you if there is a problem.

[rickallen124]

I just torqued my head bolts according to the manual and the final 180 degrees from 14 ft/lbs is really tight. It seemed that the bolt was giving the sensation of being at its maximum torque, without breaking, at the point that it reached the 180 in two steps of 90. Is that normal?

[Two-Six]

Hey guys follow the manuals exact directions. I didn't follow them the first time and when I started my bike for the first time the head gasket was leaking. I had to take it apart again to replace the gasket, once I touqued the bolts the manuals way, I never had another problem.