I'm not sure if these qualify as motorcycle boots, but these would probably all look good with a pair of khakis:
http://www.amazon.com/dp/B000AMZKOE/ref=wl_it_dp_o_pd_S_ttl?_encoding=UTF8&colid=2KDXCFB2IW71T&coliid=I12OOKA5WQ037A&psc=1
http://www.amazon.com/dp/B000HDYK7Y/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=2KDXCFB2IW71T&coliid=IUMJZRDZOMUR1&psc=1
http://www.amazon.com/dp/B002YTDMOG/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=2KDXCFB2IW71T&coliid=I3A660QW5J916&psc=1