2008 Yamaha Raptor 250SE / 250SE2 Factory Service Manual, Page 128Get this manual
CYLINDER HEAD
aTurn the Pickup coil rotor counterclockwisebAlign the "I" mark on the Pickup coil rotor with the stationary pointer on the crankcase covercRemove the wire from the timing chaindInstall the timing chain onto the camshaft sprocket, and then install the camshaft sprocket onto the camshaftNOTE: When installing the camshaft sprocket, be sure to keep the timing chain as tight as possible on the exhaust side Align the pin on the camshaft with the slot in the camshaft sprocket