03-15-2021, 11:55 PM
Watched your video with the plug lead on and off the no.4 plug, there is a marked difference in sound. I wonder if you have a burnt out valve and the noise is just the combustion escaping when it shouldn't? Take all the plug leads off and spark plugs out and turn over the engine by hand (put the bike in a high gear and rotate the rear wheel) and stick your finger in the plug hole number 4 to make sure you are getting some compression. It is a little crude I know but it might at least rule out a bad valve or closed up valve clearances. You are going to need someone to rotate the back wheel for you. If you have a compression tester (very cheap on E-Bay) even better, you can turn the bike over with the starter and check it that way.