Having replaced both kitchen taps I now only have a few seconds of hot water coming from hot taps?

having replaced both kitchen taps i now only have a few seconds of hot water coming from hot taps?
In replacing the valves you have disturbed some minerals built up on the pipe walls and now it's clogging the faucets. The solution would be to shut the water off and open up the valve, Clear the seat or inlet ports on the cartridge and then turn the water back on for a minute to flush out the hot water supply. Reassemble and test. Good luck, Tom