Help low rev issues

Hi I have just taken my 2003 KDX220 (UK) out for it's first ride since the last owner dropped it off. The bike starts fine and pulls well in high revs but in low revs it's very lumpy and lacks power.
Before I start to clean the carb out I just wanted to check to see if any one knew what the stock jets sizes are pilot and main, I wonder at some stage they had been changed over to match a better pipe (it's now back on stock)
Any other ideas would be great .
Just to add the plug is a 8 and looks dry and a dark tan in colour.
When I took it out of the engine after a 20 min ride it felt cold !.
This is my first 2stroke and I could do with a bit of help.
Thanks all Jono

Hi mate thanks for the message it looks like your are the main man when it comes to KDX220 in the UK. I have seen lots of your photos and Vids on the web.
I live in the west country not far from Bath.
The guy that I bought the bike from had only ridden it a few times and suggested that I should use 32-1 which I have mixed up and filled the tank with.
The Plug looks dry but as I said a dark brown, strange but when I removed it last night after 9 mile ride it felt warm not hot.I was planning to get a new one today.
When I bought the KDX I was looking for a green lane that would be fine at low speed but this feels much better at hi revs, not ideal for the sort of ridding I do.
I have been told to check the power valve ( not sure how to do this ).
Once I have a new plug I will give the air screw a go just to see if the pilot jet is blocked.
It's always hard starting with a new bike (my first 2 stroke) it seems to rattle more than any other bike that I have had, and I'm not sure if the other owners jetted it for a replacement pipe and the removed the pipe when they sold the bike without changing the jets.
When the bike pulls in high revs it feels great I just hope that I can get it running well down in the low rev range.
Thanks again Jono