What is the reason for frequent burning urination with no cloudiness or smell?

Thanks for asking!: The presence of burning with urination (aka dysuria) usually implies the presence of either infection (uti or std) or inflammation (non-bacterial cystitis, prostatitis, urethritis, vaginitis) regardless of smell or appearance of urine. Urinalysis and appropriate cultures would help differentiate causes.

Dysuria: Dysuria is the feeling of pain, burning, or discomfort upon urination. Although dysuria frequently indicates the presence of a urinary tract infection (UTI), it can have a variety of causes. Dysuria should always trigger a visit to a health-care professional for evaluation and diagnosis. http://www.emedicinehealth.com/dysuria/article_em.htm#dysuria_overview