Can I enter the USA on L 1 B visa while married to a USC? I intend to apply for a green card after being in the US for a bit?

You have a dual intent situation which technically is permitted. The important thing to do is to tell the truth in every representation that you make both written and oral. Since the easiest pathway to a green card is through your US citizen wife's sponsorship, I would pursue that as a priority. You should work with an immigration lawyer to handle the case from start to finish. Some of us charge a reasonable flat fee with no hidden costs. 

Dual intent means just that – even if there is an intent to immigrate to the US, the applicant can still obtain a nonimmigrant visa to enter the US. I do not see any different result just because you will not be getting the visa until after you are married. Dual intent is afforded those on H-1B and L visas. 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.