Common problem here in the UK in winter. I use a prime of model diesel fuel. Works like a treat. The ether is the key. If you can't get diesel try mixing equal parts of kerosene ether and caster together and that will do the job.

SOMETIMES i HAVE A QUEUE FOR MY MAGIC SQUEEZY BOTTLE.

Some engines just will not start at low temps due to the low vapour pressure of the active constituent of the fuel. Lighter fuel might work and Diesel engine starter spray defintely will work.