Hi there,

So last year, my ol' F2 suddenly started running on 3 cylinders after washing it. After running for a couple of minutes, the dead cylinder came back to life. Then, after driving in really wet conditions, the next time I started it, it lost spark on a cylinder once again (#3, if I remember correctly). The plug got really fouled, and since I didn't know when they were replaced last, I replaced all 4 of them.

Then, less than 5.000 km later, it happened again after riding in a heavy downpour.

It's been sitting for a couple of months now (snow and freezing temperatures here in Denmark atm.), and since I had a week's vacation, I decided I should look more into the problem, as well as carry out a full service.

I'm cleaning and syncing the carb, as well as replacing oil/filter, air filter (which was really grimy), and spark plugs.

#4 was really fouled up with carbon deposits, so that's probably the one that stopped firing. #1,2,3 look alike, and seem pretty healthy to me, but I'm by no means and expert. Unfortunately, I started cleaning #4 spark plug, before I decided to just buy new ones (and take pictures), so in the image below, it looks a lot nicer than it did initially.

Do any of you more mechanically inclined people have a suggestion as to what could cause the "dead" cylinder? Damaged HT-cable/plug perhaps? Or a sketchy solenoid? On a side-note, after removing the carbs, I found out that the o-ring between cylinder #4 on the throttle body and the air filter-thingy was missing.