Torqing head bolts

[YFZer]

I don't understand what the service manual is talking about when it said that you put a line on the bolt and turn it 180 degree. You tighten the head bolts to 30nM then lossen and tighten again to 20nM. Then it talks about 180 degrees . What does it mean?

[jshtex]

This is from memory but it sounds like you have a manual so you should be able to follow me....

First off, I always use new bolts because they are tty (torgue to yeild) and they stretch some every time you torque them. Plus they are cheap.

Clean and oil the bolts.

Install them finger tight in thier holes.

In the correct order (in the manual) tighten them to 30 ft lbs (check the manual to verify the torque value).

Back them off, remove them and re oil them, and then put them back in finger tight.

Tighten them to 20 ft lbs (again check the manual).

Mark each bolt and the head with a line from the bolt head down and onto the head surface. ( I use a sharpie).

In the correct order again (from the manual) turn each bolt 90 degrees. (one quarter turn).

Then go back and in the correct order turn each bolt 90 degrees (another quarter turn).

Now the marks you put on the head of the bolts should be 180 degrees (opposite side) from the mark on the surface of the head.

The bolts are tightend this way because of the torge to yield stuff, they want a certain amount of stretch.

Again this is from memory so please follow the manual if it says different.

[cals400ex]

yeah it is a weird process with their manual. a few builders i talk to say they torque them to 28-30 ft-lbs. that is probably what i am going to do. everyone has a different technique but this one sounded by far the easiest.

[loons]

Everything he posted is correct, except it is 22 ft lbs, and then 14 ft lbs

[rpyfz450]

Read your manual and refer to the illustrations in there.

a. Wash the threads and contact surfaces of
the bolts, the contact surfaces of the washers,
the contact surface of the cylinder
head, and the threads of the crankcase.

b. Apply molybdenum disulfide grease on the
threads and contact surfaces of the bolts
and on both contact surfaces of the washers.

c. Install the washers and bolts.

d. Tighten the bolts to the specified torque in
two or three steps in the proper tightening
sequence as shown.

e. Remove the bolts.

f. Again apply molybdenum disulfide grease
on the threads and contact surfaces of the
bolts and on both contact surfaces of the
washers.

g. Retighten the bolts.

Cylinder head bolts
1st time
30 Nm (3.0 m · kg, 22 ft · lb)

Cylinder head bolts
2nd time
20 Nm (2.0 m · kg, 14 ft · lb)

h. Put a mark on the corner 1 of the cylinder
head bolt and the cylinder head 2 as
shown.

NOTE:
Tighten the bolts 90° in each of the two steps
to reach the specified angle of 180° in the
proper tightening sequence as shown.