Hi rtwiza,
How much bigger is the copy than the original?
If you press the Copy button on your PIXMA MX892, on the LCD does it show 100%? If so, press the right Function button and change "Magnif" to 95% and then perform a copy. Does changing this setting help?
If you continue to have difficulties, please contact our support group using the following link:
http://www.usa.canon.com/cusa/consumer/standard_display/contact_us_consumer
