I own royal enfield Thunderbird 350. It's getting on in one kick, and will be on as it is untill I don't off it, but as I touch accelerator it will be off. One other issue(not sure if its related), if I don't start bike for 2-3 days, then it will take lot of time to start, probably 40-50 kicks.
I faced a similar issue when some amount of water entered by Fuel Tank due to which the bike was getting started but turned off as soon as i revved it. I took it to the mechanic and he removed the fuel tank then cleaned and dried it. After that i haven't faced the issue.
Also a tip for starting your bike in winter which I usually do, I turn off the kill switch and then kick the bike for 2-3 times. Then I turn off all the switches(headlamps, indicators etc.), turn on the kill switch and then retry kicking. I mostly get it started in the very first kick only.
Happy and safe riding.