No, unless your doctor prescribes it that way, which I highly doubt any doctor would. Motrin (ibuprofen) thins your blood, and would be very, very dangerous should you get hurt. Also, there is a risk of overdose taking that much. If the Motrin you have been prescribed the 800 mg for is not helping the pain, you should contact the Doctor that prescribed it, and he/she can try a different medication. Never adjust your medication without first talking to the professional that prescribed it. Also, don't even take my word for it. Call your Doctor. I, like many people on ask are not a physician, and when your life is at stake, take no chances. All prescriptions are not written the same. A doctor might have one patient taking 4 a day, whereas another doctor might have the patient taking an entirely different dosage.
800mg should really be your daily limit. NSAIDS are the best pain reliever as they also reduce swelling. But if 800mg isn't enough consult your doctor to see if something else would work better. Too much pain killers can actually make you more sensitive to pain. Meaning if you take too much pain killer on a regular basis you will feel pain more than if you didn't take any.