My Hero Karizma R 2008 has starting trouble. What could be the reason?

Hai, i have purchased a second hand Karizma R 2008 model. The bike has run 31000 km till date & there are no engine troubles also. The major issue is that takes at least 10-15 kicks to start the bike. This is not the case with winter season, even in peak summers also the same issue exists. Someone suggested to open the petrol tank n shake the bike 2-3 times and start using choke. Even this procedures takes hell lot of effort and time. Once consulted hero showroom and they say this is a common issue with 2008 Karizma r. can anyone please suggest a solution or some good showrooms (South Delhi) so that this issue can be solved. Thanks, Deepak