Not much experience with YZ,s just pulled a unmolested 400C I've had under a tarp for several years out to see if it's worth restoring. The bikes complete with air forks ,side stand , sump guard and original air box. My first dilemma is the bore 85mm as apossed to the original size of 82mm. Are pistons available ? The bore may be usable with a light hone with approx .002-.003" wear. Any advice would be appreciated. Thanks Terry.