EXC 300 idle jetting

Struggling a bit with the idle jetting on my exc 300. It pulls like a train as soon as you open the throttle but tootling around just off idle it splutters and farts
The carb is clean, as is the filter, reed valve is ok etc so am sure it's down to the idle jet/idle air screw.
It's currently running a 42 jet whic i reckon is too rich. The manual lists a 35 standard and a 48 for running in. Has any one who has had one of these had any similar probs?
The last couple of time i've been out it's been really cold (snowy) which the thing doesn't like either so I've not made any changes.
Now it's warming up a bit i want to get it sorted though.
All info appreciated

Hi Pigglet have a look on the thumpertalk website you'll find the answer there.There's a section just on carbs and jetting they know their stuff

powervalve

check the powervalve screw on the right hand side of the bike, if its been screwwed in it will be very woolly at the bottom and fly once the gas is on past half. you said the reads are ok, did you check for cracks cos that cause real low down woollyness. is this something thats just started cos they do wear out the main jet and needle cos it vibrates aroung and wears the hole.

I can't get on thumpertalk at the mo but will have a look later.

I'll check the reeds againeiher tonight or tomorrow as I'm going to pull the carb off again

Went up from a 42 pilot jet to a 45 yesterday but it didn't make much difference

It accellerates hard and cleanly right off the bottom it's just when cruising at very low revs with the throttle only a few mm open that the problem arises.

I'll check the main and needle tonight but they seemed ok. will check the powervalve too

Spoke to leisure trail who told me that after 2004 the engines were considerably smoother, mines an 03 might just be me being fussy