As a general principal, a carburetted engine should
not be started with throttle advanced and choked at the same time - If your manual says to use throttle, only use very very little - fast idle position only.
Many of the smaller, usually single cylinder engines, have throttle/choke on the one lever - in this case the manufacturer has designed the system, to cold start with wide open throttle and closed choke, you have no choice in the matter and it usually works quite well.
With larger engines, that have been fitted with a separate choke, opening the throttle fights/apposes the closing of the choke - so starting will be difficult (particularly in cold weather).
With my larger mowers, for a cold start,
- I make sure the throttle is fully closed.
- I close the choke fully (usually a pull up button ).
- Crank the engine very briefly.(If no immediate start, do not continue cranking, as this may flood your carburettor and stresses your starter motor/system unnecessarily)
- If start, I allow engine to run for a few seconds, until I can hear a change in engine note, I then slowly open (push down choke button) until smooth idle is achieved.
- If no start, I open my throttle very slightly, to fast idle position (no further) and crank again. I always get a start at this point, no matter how cold or long, it has been sitting. Again I wait until the engine note changes and I start to open the choke gradually (push down choke button) until smooth idle is achieved.
Note: Always allow a few moments/minutes for your engine to warm up. Engaging drive or cutter system, when engine is still cold, is likely to cause it to run roughly or even stall. At the end of work allow a few minutes for cool down befor shutting off (this is the time I take to blown clean my mower)