No and may be, Clutch while plays important role in affecting top speed but as you mentioned you just changed it, should not give less top speed.
As you got the servicing done there might be few mechanical issues such as
- Slipping clutch (even new ones sometime can be defective thus dissipating power while slipping), caused by worn out disc or incorrect order of discs
- Clutch wire is too tight or too loose.
- faulty clutch master cylinder
- loose clutch master cylinder nut
Some factors that we oversee are not mechanical such as
- weight between different measurements, weight of petrol/pillion/luggage etc.
- faulty/uneven air pressure in tyres can cause different top speed.
- wind drag, opposing wind can reduce the speed as wind speed can range from 5 Km/h to 15 Km/h in normal days or open fields/highways.
I would suggest following measures -
- multiple speed runs on safe roads while following same acceleration method.
- Keeping petrol amount roughly same while doing speed runs , gist is keeping the weight constant.
- proper air pressure which is neither too bouncy(when you fill higher than suggested) nor too limp ( when air pressure is less than suggested).
- check chain slack.
- check wire slack in both clutch and accelerator cable.
- cleaning of throttle body if due.
- change in air filter if due.