Motorcycle Repair: oil change, stator coil, metal shavings

Question
hey chris, 2 quick questions.  I just got a 1991 nighthawk 250.  I know there is no oil filter, but where do i drain and change the screen from? also, i thought it had a dead battery, so i replaced it with a new one, it ran fine for a month and then the battery died. i know on a car this usually means the alternator, but what charges the battery on a bike? thanks for any help you can give.
johnny

Answer
Hi Johnny.
 What leads you to believe that there is no oil filter?  Every engine has one.  It needs it to filter out contaminants that can destroy an engine.  Granted that it may not be obvious, but it must be there.  The oil drain is always at the lowes point of the motor.  It may not be immediately obvious, but it will be a bolt with a head tha is 15mm or larger.  It may also have a screw in the center.  That screw (if it's there) is a magnetic pickup.  It it's purpose is to grab loose metal shavings to help the filter and keep them out of the system.  If you have one, then clean the shavings off when you change the oil.

 Get the repair manual as you will need it for maintainence schedules and other important bits of information.

As far as the charging system is concerned, on a motorcycle the power comes from a stator coil.  This coil should produce between 13-15VDC.

The way to see if the stator is working is as follows;

1) Start the bike.

2) Test the voltage at the battery terminals with a multimeter set to DC volts.  The voltage should be between 13-15 VDC.  Rev the bike a little (no more that 3500rpm) for a second or two and watch the voltage.  If it is below 12 VDC or drops voltage (volts begin dropping and continue to do so) at idle, then the stator is bad and needs to be replaced.

Good luck.
FALCON