Numbers on bolts

[donald m]

Do the numbers on Yamaha bolts indicate torque? If so, are they in kg, inch pounds, or fp?

[fairdeal]

No
but that's a neat idea, right?

the Official Service Manual for each engine identifies the recommended torque for each bolt

there's really no shortcut....

[boscoe99]

To add to what Fairdeal sez, it is not practical to specify a torque value on the head of a bolt. As he notes, you really need to refer to the applicable service manual. The same bolt can have different torque values depending upon where the fastener is used. In a number of cases, the may be three values for the same bolt. An initial torque value, a second higher torque value, and then finally a turn to value (say 90 degrees).

As important as torque is, the SM will also specify the torque sequence. Let's say there are 12 bolts used to hold a cylinder head in place. Yamaha will specify which bolt is torqued first, second, third, etc.

Torque is expressed in lb-in or lb-ft in the English system. N-m in the metric system. Many will erroneously refer to it in-lb or ft-lb. Better to get it right. Actually, it is as easy to be right as it is to be wrong.