What can cause a misfire on 3rd cylindar

Misfires occur when the combustion process is incomplete, so you need to find what's missing.

Look for a bad spark plug, incorrect plug gap, deteriorated spark plug wire, or incorrectly centered spring electrode. Coat the porcelein portion of the plug and top electrode with a light coating of dielectric grease. I only recommend NGK plugs in Hondas. Worst-case scenario would be a bad valve, which is easy to verify with a compression check. Never adjust the valves on a Honda too tight--it would be better to have them a little loose. Then, exhaust valves don't get burned or cracked.

If the problem persists, consider replacing the igniter. The rotor and distributor cap should be replaced every 60,000 miles. Igniters and coils should be replaced every 120,000 miles or 10 years, whichever comes first.