Why do I see smoke on cold start ups on my 1991 Honda Accord?

Assuming that you're talking about the engine being cold and not the temperature, two things cause smoke to come out of the tailpipe, and I listed them according to likelyhood. 1. Oil. This produces a blueish tinted smoke. As your car ages, seals inside the engine begin to break down. A common cause of smoking on start up is leaking valve stem seals. When the engine sits, oil drips down the shaft of the valve, and pools in the cylinder. When you start the car, it burns off, causing the smoke. Untill it becomes an constant smoker, the car can still be driven, as long as you keep the oil topped off. Make sure to change it regularly and consider switching to a "high Mileage" type of oil, using an additive, my favorite being Lucas Oil, or both. 2. Leaking head gasket. This produces a thick white smoke. This is unlikely, because it would smoke consistantly.