If the bike was hard to kick in the past and is easy to kick now, something has changed.
Do you have a dial caliper? If not they are pretty inexpensive and you should get one if you want to get the engine optimized so it runs best for the fuel you plan to run.
If you have a flat top piston and a head for a domed piston, it will have really low compression.
If the new cylinder is slightly taller than the previous cylinder, it will lower your compression ratio. Some people cut the base of the cylinder to increase low end torque and move the power band to a lower rpm.
If you used a thicker base gasket under the cylinder it will raise the cylinder and move the power band to a higher rpm and it will also lower your compression ratio.
I would run a compression test after you break it in. It should be somewhere between 160 and 180psi. A little higher is ok but you will need to run higher octane gas. Lower than 160 I would probably make some changes.
Did you install a new piston and rings? If so what part number?
If you really want to know how well it is set up I would also try to run a squish clearance test with a piece of solder.
https://youtu.be/1dfBB-_5rQ8
You can drain the coolant and pull the head off as shown in the video which will be the most safe and accurate.
You can also try to bend a piece of solder 90 degrees and stick it into the spark plug hole and pull it up high so the end of the solder is in the top corner between the head and cylinder. When you cycle the engine with the kick starter it will deform "squish" the solder. Once you deform/squish the solder you can take it back out to measure it to know your squish clearance and angle.
If you insert the L shaped solder through the spark plug hole you need to be careful you do not insert it too far so as to get the solder stuck into a port where it will cut off by the piston and it will drop into your bottom end where it will do "bad" things.
I would run it for a little bit before you do the compression test. You should be able to run it around the block now but be careful not to rev it to high as the cold weather often requires richer jetting. If you can get some AV fuel or race fuel without ethanol in it, it will run richer and compensate a bit for the cold weather.