Yamaha YZ250/LC Manuel Du Propriétaire page 552

Table des Matières

Change of the heat range of spark plugs

Judging from the discoloration of spark plugs, if

they are found improper, it can be corrected by

the following two methods; changing carburetor

settings and changing the heat range of spark

Standard spark plug

In principle, it is advisable to first use spark

plugs of standard heat range, and judging from

the discoloration of spark plugs, adjust carbure-

tor settings.

If the calibration No. of the main jet must be

changed by ±30, it is advisable to change the

heat range of spark plugs and newly select the

proper main jet.

When checking the discoloration of spark

plugs, be sure to stop the engine immediately

after a run and check.

Avoid racing.

When changing the heat range of spark plugs,

never attempt to change it more than ±1 rank.

When using spark plugs other than standard,

make sure of the difference in heat range and

find the equivalent to the standard.

Note that even if the discoloration seems prop-

er, it may slightly vary with the spark plug

maker and oil in use.