Suzuki DF2.5 Idles Too Fast

[DOILY]

I've never had this problem before, after 6 years of trouble free use from new. I've stripped and cleaned the carb. Fresh fuel.
It is too fast to engage gear, even with idle adjust screw backed right off and the throttle cable disconnected.
Thank you in advance for your help and advice.

 

[VicS]

Even with the throttle cable removed and the idle speed screw backed right off there must still be something holding the throttle valve open slightly.

I'd inspect the valve flap itself, looking for some reason it is not closing fully. This will need the carb to be removed again therefore firstly I would look at the operation of the choke. I notice from the illustrations in the service manual that there is a cam on the choke which opens the throttle a little when t the choke is closed. I'd look at this mechanism to see if it is holding the throttle valve open a little when it should be closed. Is there something preventing the choke from opening fully?

.