Hi guys, got a 1997 thunderbird 900 with a rather nasty misfire. After changing a duff battery and cleaning the plugs after a starting issue i now have a misfire with flame and black smoke coming from the left pipe on the overun. The only other thing i did was to drain the carbs and put fresh fuel in the tank. Any ideas and help on what the problem could be would be greatly appreciated.
If all you have done is drain the carbs and refuelled then my guess (for that is what it is, but is what I would check first myself) would be that you have disturbed some muck in the carbs which is now seeking revenge on yourself by giving your bike some sort of indigestion. May be worth draining the left - and possibly the centre - carb(s) again. Daft as it sounds, it may even clear itself if you are really lucky - but don't hold your breath on that one!
I would agree, the fact that you have black smoke & flaming would suggest one of the carbs is pouring in excess fuel. You could try tapping each carb float bowl , a long shot but worth a go. Then unfortunately sounds like carb strip
You have by drawing the carbs allowed the floats to drop to their lowest level. May be one has not popped back up, hence the tap tip
Dirt / grit on float needle seat, more likely the float needle hasn't settled back properly when re-fitting the float bowl. As Ken has just suggested tapping the side of the carb around the floatbowl with the plastic handle of a decent sized screwdriver may just settle everything back, but its a longshot and will probably mean the floatbowl being removed and refitted taking care to ensure everything is spotless and back in place. If the carbs had gone dry sometimes the needle tip drys out ( if its a rubber tip ) and becomes softer and seals better once its been soaked in fuel for a time.
It's all starting to make sense now. Thanks so much for your help guys, will let you know how it goes.
check pilot jets are clear. only way is to push copper wire through. Air or even ultrasonic won't do as the hole is too small, copper will not harm the brass jet. Also check o rings on the float valve.
My favourite is Redex - but use whatever you can get ... every little helps, as the old lady said as she peed into the sea (one of me mum's favourite sayings - very wise was my mum!!).
lol did she use redex as well? I use redex every other fill up in my Sprint, it has made the bike run and idle much smoother, tho it took a few tankfuls to get where I am now.
Good news. With a bit of fiddling and tapping with a screwdriver along with some additive it's running properly again. Will have to get a full carb strip and clean at some point but that can wait for winter. Thanks everyone for the advice.
