Circuit City Stores, a Richmond, Va., operator of consumer electronics stores, announced record sales and earnings for the second quarter ended Aug. 31. For the quarter, sales totaled $217 million, up 47% from the same period a year ago. Net income was $7.1 million, up 80%. The company also said the Internal Revenue Service is examining its tax returns for fiscal years 1983-85, during which the company used most of the net operating loss carry-forwards resulting from its 1981 merger with Lafayette Radio Electronics. An IRS agent has indicated that he will recommend disallowance of such deductions for those years. The company said it intends to "vigorously defend" its position that the tax losses are valid. Should the IRS win its case, the company said it will absorb a one-time charge of about 70 cents a share.