  We report our measurements of the bulk radial velocity from a sample of
small, metal-rich ejecta knots in Kepler's Supernova Remnant (SNR). We measure
the Doppler shift of the He-like Si K$\alpha$ line center energy in the spectra
of these knots based on our $Chandra$ High-Energy Transmission Grating
Spectrometer (HETGS) observation to estimate their radial velocities. We
estimate high radial velocities of up to $\sim$ 8,000 km s$^{-1}$ for some of
these ejecta knots. We also measure proper motions for our sample based on the
archival $Chandra$ Advanced CCD Imaging Spectrometer (ACIS) data taken in 2000,
2006, and 2014. Our measured radial velocities and proper motions indicate that
some of these ejecta knots are almost freely-expanding after $\sim$ 400 years
since the explosion. The fastest moving knots show proper motions up to $\sim$
0.2 arcseconds per year. Assuming that these high velocity ejecta knots are
traveling ahead of the forward shock of the SNR, we estimate the distance to
Kepler's SNR $d$ $\sim$ 4.4 to 7.5 kpc. We find that the ejecta knots in our
sample have an average space velocity of $ v_{s} \sim$ 4,600 km s$^{-1}$ (at a
distance of 6 kpc). We note that 8 out of the 15 ejecta knots from our sample
show a statistically significant (at the 90$\%$ confidence level) redshifted
spectrum, compared to only two with a blueshifted spectrum. This may suggest an
asymmetry in the ejecta distribution in Kepler's SNR along the line of sight,
however a larger sample size is required to confirm this result.
