The engagement dogs on the 1984 FJ 1100 second gear were cut too shallow for the power they had to absorb. Many FJ´s with as little as 10,000 miles can jump and stutter under power while in second gear. In 1985, Yamaha is said to have corrected this problem by redesigning the dogs with a deeper undercut. If you bike has this problem, second gear and the gear it mates with will both need to be replaced. If it does not, I understamd the gears can be machined to avoid this slipping and subsequent damage.