  We demonstrate the effect of single-electron tunneling (SET) through a carbon
nanotube quantum dot on its nanomechanical motion. We find that the frequency
response and the dissipation of the nanoelectromechanical system (NEMS) to SET
strongly depends on the electronic environment of the quantum dot, in
particular on the total dot capacitance and the tunnel coupling to the metal
contacts. Our findings suggest that one could achieve quality factors of
10$^{6}$ or higher by choosing appropriate gate dielectrics and/or by improving
the tunnel coupling to the leads.
