What weight of oil are you using?
At those temps you should be using something lighter than what is normal and it really should be synthetic because the paraffin in conventional oils makes it too thick at those low of temps.
What fuel octane rating are you using?
In some northern U.S. states, they have a lower octane winter formula for gasoline. I've seen some down into the mid/upper 70 octane. I don't know if Canada uses the same method to rate gasoline octane. Would also need to check that out. High octane fuel will struggle to ignite in the low compression 200ES engine at the temps you are using it in.
Which spark plug are you using?
This will have more to do with operating conditions than starting. I can't say for certain, but at those low of temps the standard plug heat range may cause issues like fouling. Honda typically gives a part number for one above and one below the normal heat range spark plug. A hotter plug may make it run better once going and warmed up as much as it can.
The carb adjustments will be off at those temps, regardless of elevation. Colder air is more dense and more fuel can be mixed with it. At this point though, I think oil flow is the most critical concern. Too thick of oil at those temps will certainly cause accelerated startup wear.
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