T5 revving its nut off

Have just rebuilt and fitted my T5 engine, it is standard. When i first started it the revs were very high, i could not set them with the adjustment screw. Took carb off and surround and refitted ( this time with air filter!). This time a bit better but i still think it is revving too high even without the tickover screw in.

I have also noticed a petrol leak, somewhere inthe carb/surround area, nothing obvious but there is a constant drip under the engine, could this have something to do with the overrevving ( ie an air leak some where )

Hope some one can help
Cheers Andy

Hi Andy
Have a look to see if the carb cable is slack on the carb box end? and have you put on new gaskets on the carb and under the carb box,