My L1 b is denied and I94 expired but I have valid B1 for 3 years. To maintain business continuity for short period of time, can i stay using b1?

Unfortunately, you cannot as you entered the US on your L-1B and that is your last legal status in the US. In other words, you cannot unilaterally change your status in the country. You would only be allowed to become a B-1 visitor if you successfully made an application to change status in the US or successfully reentered the US on the B-1 visa. I note that USCIS seldom allows changes of status where the I-94 is expired and that a B-1 visa is automatically canceled once an individual overstays the period of legal stay in the US. I further note, however, that staying a few  more days in the U.S. albeit without status should not appreciably change your legal situation for the worse. Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.