What's Does the adjustment screw on top of carb do ?

[postysteve]

OK, this might seem a daft question to you? but to us newbies only way to find things out is to ask? and there's no harm in asking is there !!

What i want to know is as i've never done anything with it ?
what is the adjustment screw for ? or do? on the top of carb i take it it must have something to do with the throttle but what ?

please see photo

 

[Pablo]

Simply adjusts throttle cable tension. You want the tension just barely loose - certainly don't want any pull from that nut.