Maintenance - Yamaha YTZ250S 1986 Service Manual

4. Remove the Y.E.I.S. chamber.
5. Remove the three bolts from the cylinder
head holding brackets, and remove the
brackets.
Bracket to:
Frame 30 Nm (3.0 m.kg, 22 ft·lb)
Engine 55 Nm (5.5 m.kg, 40 ft·lb)
6. Loosen the six cylinder head nuts a
quarter turn each in a crisscross pattern,
then remove the cylinder head nuts in the
same pattern.
Remove the cylinder head and head
gasket. And discard it.
3-12
Cylinder head nut:
25 Nm (2.5 m.kg, 18 ft·lb)
Maintenance
1. Using a rounded scraper, remove cabon
deposits from combustion chamber. Take
care to avoid damaging the spark plug
threads. Do not use a sharp instrument.
Avoid scratching the metal surface.
2. Place the head on a surface plate. There
should be no warpage. Correct by resur-
facing. Place 400-600 grit wet emery
sandpaper on surface plate and resurface
head using a figure-eight sanding pattern.
Rotate head several times to avoid remov-
ing too much material from one side.