All 2st A quick jetting question hopefully

Last sunday i was out trail riding on my 99 wr 250 and after coming coming of a fast section and throtling down i nocited it was surging. Does this mean its running lean the pilot is a stock 40, stock needle but on the second clip and 390 main. the plug looks on the dark side. but even the needle was the stock clip position there was a little bit of surging which way should i go to cure this. the carbs been clean and spotless and there is no problem with fuel flow from the tank to the carb.

Has the bike been running fine and this surging just started to happen?

Can you get it to repeat this performance or was it a one time occurrence? What I mean is if you were hard on the gas and you chop the throttle the bike briefly goes lean as a function of riding conditions but if it continually surges it indicates a real problem.

Yes, surging indicates lean. Yes, with the throttle closed it indicates pilot or slow speed circuit. If the bike has been working with this jetting it could indicate a partially blocked pilot. If the pilot is blocked the bike should be hard to start. Another source of possible leanness could be a leaking crank seal but I would start with the carb.

Come to think of it she was been a bit of a pain to start last weekend. im going into to have another look I maybe some time.

Ive had a look at the carb and manifold joints and had visual look at the ignition side crank seal also i had a spray around with wd40 and still nothing showed. What i did find is water in the float bowl. So i cleaned all of the carb and jets out with an air line and put the needle clip back to stock. Put it all back together and fired her up, she idles fine and revs cleanly. But one thing i notice is she to get warm fairly quick and she hasnt done that before any ideas. I,m taking her for a trail ride on sunday ill let you know what happens, i hope she will be ok.