2000 wr400 hard start/backfiring poor throttle

hey guys, as the title says im having trouble with the bike. it got stolen then returned (5yrs l8r) and ive fixed the thing up to pretty much immaculate. the trouble now is its very hard to start, has very poor response down low and just now when i started it - was backfiring/popping intermittantly. the carb is squeaky clean and have checked several times. i have done the yz timing but it ran fine afterwards. it was just all of a sudden this started to happen, random. the valve clearances are sweet also. the thing is sometimes it runs better than others, but the poor response is always there. could it be electrical or the ignition timing or something ? would the accelerator pump do this ? its still stock. any ideas ? cheers.

well, update. i managed to keep the bike started by holding the throttle bout 1/4 open, it stopped popping and came to idle eventually. i then decided to go for a lil spin. gave it a bit of wot etc etc and when i got home 5 mins l8r all probs were gone !!! even the poor throttle response, u can snap it as quick as u like now !!?? also it used to idle high for a second on deceleration before returing, this is also gone !!?? im baffled now, and really hope it does not come back. one thing i did do was spray the hot start with inox, but still not sure.

Does "carb is squeaky clean" mean you took out the jets and cleaned them?

It sounds like what my 2000 WR is doing and I know it's a clogged jet from sitting with the fuel on over the winter and no Sta-Bil. I really need to smack my brother up side head for turning on the gas.

In your case maybe something got by the fuel filter or something was just stuck and shook loose. But I'm just guessing.

hey thanx for the reply bud. yes all the jets were cleaned a couple of times. i even at one stage had a 50 pilot and 178 main jet in but changed bak to stock because i was having these symptoms really bad. it wasnt because of that tho. im pretty stumped hey. the bike at the moment is running sweeeet and when its hot the throttle resp is crispy as. im in the habbit now of draining the carb every time it goes in the shed. fuel filter is new/clean.

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