A while ago I changed the rocker cover on my 89 FH. since then it's backfired which would suggest lean mixture. Although it backfired during start up, once it turned over it the backfiring would stop and run as normal. I haven't ridden the bike this year yet but since February I have turned it over every couple of days so that the battery isn't flat and that theres no gunk build up inside the engine. 2 days ago, I started it and it started first time. Now though it just will not start at all. The backfiring is now so loud its like someone threw a flash bang in the room.

Can anyone think of a reason why it would start one day and decide to give me the two finger salute the next day? I added fuel to it incase it was it was running dry but still no luck and the kill switch is at run.

 

Kinda sounds like your timing somehow got out of whack.

 

Timing wouldn't change just sitting there.

I would clean your carbs and make sure your mixtures are set correctly. Check to make sure you don't have any leaks in your intake boots, and the nuts for your exhaust headers are all snug.

Check your plugs, replace if necessary.

 

Unless a bolt holding the ignition trigger in place has come loose then it is unlikely to be retarded ignition. I'd guess you have a hole in the exhaust somewhere as suggested. A weak mixture is another thing to check for in the carbs.

 

cause probably you fouled the plugs, and fuel is gathering and when there's a tiny spark, baaam, backfire

 

Try this and see if it works: Open the throttle slowly to the fully open position, then crank the motor. It may start, but if not doing this should clear any excess fuel from the engine. Try again with the throttle fully closed and if it starts don't rev it too much, too soon. You may eventually have to take the sparkplugs out and hold them over a gas flame or similar to get them warm (not glowing!),then quickly replace them and have another go. Hope this works for you so you can go out and have some fun!

 

I once had a similar symptom in my f2, first poor starting and then nothing else than a deafening blam from the pipe, fresh set of plugs fixed it right up.