I'm lookin at an 08 big bear 400. It's in great shape with around 900 miles an original owner. What concerns me is when I asked him about maintenance, the only thing he has done is change the plug and clean the air filter. Never an oil change. How concerned should I be with this? Thanks for any advice.

 

I'm not real familiar with changing oil on 4wheelers far as how long it last per change. Personally i change mine ever 6 months regardless. plus if i remember they tell you to change the oil twice a year???? at least on a car regardless of how many miles.
If he never changed the oil did he ever grease it? Did he even care how hard he rode it.
I'm not saying to worry but you have to wonder if he even took care of it at all. This may not have any effot or it may

 

How many miles on it? Check the dip stick and see the oil condition. A guy who burns only two tanks of gas a year does not need to change the oil like a person who puts on 2000 miles a year.
If its not blowing blue smoke then the motor is ok. Take it for a ride or at least rev it up parked ,it impossible to hide a ruined/worn out motor.
There all sealed u-joints and bearings on stock Yamahas so there would not be much greasing needed.
I can,t find one grease fitting on my Yamaha.

Tuff bike, I treated my 1989 Big Bear like a red headed stepchild yet it was super reliable and is still going to this day. Sold it to a friend.