Hi,

I have a '99 ltf-500 quadrunner and it is running (barely) horribly. I have a K&N filter (just cleaned), but it is running rich (black puffs of smoke), backfiring, won't idle and is fouling the plug. I have never changed anything with the engine (it was jetted to run in Colorado, and used to run like a champ) but it sat for about 8 months and has run bad since. Think there is a carb problem (float stuck or something)?

ideas?

Carbs are very tricky beasts. First i'd try to pull the needles, clean them really well. Use a sonic parts cleaner if you can (i have one of you want to ship them) Next try pulling the float bowls, and see if you have a stuck float or a float spring. After that, if it still doesn't work, look at rebuilding the carb. Its not hard if you pay attention to what you are doing, be careful and can get the right parts for it.