100MHz RX VCO Frequency?

What is the limitation when changing a RX VCO operating frequency from 145 ~ 160MHz to 108 ~ 123 MHz? I tried to tune the tank circuitry but the frequency cannot go lower than 115MHz at lower frequency and there might be start up issue. Please advice.

What happens when you decrease the frequency?

Not to say what will happen if I decrease the frequency. I actually need and have to make sure the operating frequency starts from 108MHz. or in other word, I need the system to oscillate from 108MHz. But now the system starts to oscillate at 115MHz and not 108MHz. Based on calculation, I should be able to get lower frequency if I increase the tank capacitor but somehow the system has start up issue.