poor running at low revs

[Jonooffler]

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

[IdahoCharley]

Do you know how to check and verify that your power valve is working?
If it is stuck "open" then you lose a lot of low rpm power.

Suggest searching the forum first using term "power valve". I pretty certain there are one or two threads out there. Could also be jetting or reeds or improper timing, bad ignition wire, or partically fouled plug. Start with the easy stuff first. Power valve operation, spark plug condition and condition of ignition wire and grounding on coil.

[Jonooffler]

Hi thanks for the input i just thought that I should add that when I said lack of power it feels more like bogging down from cold the engine dies when you open up until you hit 1/2 way on the grip.The bike has been unriden for a few months and has low mileage (1600 miles) I just wondered if the jets had been changed at some time and that it was over or under jetted.
Jono