Look at the vin tag on the steering tube.
it depends there is no real schedule but if you think you are losing power you can do a leak down test and that will tell you if its time yet
Can you please tell me what type of pit bike do I have
I have a ktm dirt bike trying to find out the year the number is ktm8701*45853*
Not as easy as it is to call Yamaha with your serial number and have them tell you exactly what it is.
how can i tell the year model of a Yamaha 80 dirt bike serial number 367-230432
goole the siriel number located under th seat
Get a new bike.
On my Francis Barnett power bike, the serial number can be found on the left side of the bike just below the top of the gas tank.
Find the serial number on the engine, call up a motorsports place and they should be able to tell you what year the bike was made.
1996
VIN: JYACB03W6YA009925 2000 Yamaha TTR90