Any guesses as to why I cannot adjust the idle speed below 1800 rpm? I have tried adjusting it at the idle adjustment screw of course but it just unscrews below 1800 rpm. I have also cleaned the air filter thinking it might be blocked making the mixture rich but to no avail. The bike is new to me with 52 k km on the clock and starts without choke even when cold. Otherwise it runs well. I was wondering if it might be the air mixture screws on the twin crabs but don't want to fix anything if it ain't broke. Is there a reason why someone may have mis adjusted them or any other reason the idle may be high?

Thanks

Tim