Yamaha 250GETO Service Manual page 18

GEN
INFO
Cylinder sleeve
The slit of exhaust port is removed and smoother curved exhaust port is used on, which can pre-
vent the piston rings from scuffing with lesser fuel.
Cylinder body
The shallow water jacket is designed to increase the rigidity of cylinder body.
Wider rib is used to obtain rigid cylinder body.
Smoother curve structure is given to the #1 and #2 exhaust passages to reduce resistance of
exhaust gases.
250A
1-13
General information
250A
Exhaust slit
Rib 5mm
Deep water
jacket
44 — 96mm
Average 72mm
Sleeve
Cylinder body
250G
250G
Wider rib 6mm
Shallow water
jacket
44 — 60mm
Average 57mm
6S35H11