Yamaha yz250 vin jya4d0w0xna001734 what model year is it?
The tenth character 'n' indicates the manufacure year of 1996
1988-1991 yz250 motors are completely interchangeable. Some parts like the cylinder head use the same casting from 1988-1996. Note: although interchangeable the cylinder ports and cylinder head combustion chamber shape differ form year to year. The optimum setup for a 1990 yz250 is a 1991 cylinder with a 1992 head.
It all depends on the rider. The 2003 Yamaha YZ250 has a seat height of 38.9 inches and weighs 213.8 lbs. If you're tall enough that your feet can touch the ground while sitting on the bike and you're strong enough to hold it up, you are probably physically able to ride one. The best way to find out is to go to the nearest Yamaha dealership and ask to sit on a YZ250. The…