Hi, I'm new to the forum, thought I'd help a fellow owner out; since the thread isn't very old yet and the OP was anticipating use in the spring.
What everyone is saying about placing the pull-start at the correct compression placement is spot on. Learning this the hard way certainly makes the rope 'feel' pretty short, particularly as starting the KD420 engine manually requires some commitment; I was taught a lesson or two the first time myself (after a messy battery failure). Left the key in the house the other week, had muddy boots on, and just wanted to warm the engine up before use; so I decided to go manual, in 3 or 4 tries it started at 40 degrees F (I'm a desk jockey, but have been working out with free weights lately). At that temp it took a minute or two to reach a proper idle, sputtering until it got there. A running temp 'stalled' engine should be quite effortless.
The key to going key-less with the KD420 equipped BCS853, which means dealing with a no battery power situation anyway (I think?), is to disengage the low oil pressure fuel shutoff valve (I'm not an engine guy, so my nomenclature and conceptual understanding is shaky); I think this emergency value is only open when power is available, so the lever needs to be moved to the bypass position (I don't have this orientation committed to memory, and I'm not certain the valve hasn't changed within the KD420 series). I'm pretty sure about all this in practice at least, since turning the key off when the lever is in bypass position doesn't turn the engine off (assuming the red handle is still pressed); so correspondingly I think bypass is necessary to start manually, at least if battery power and the key (at ON) isn't available. I've never gotten it pull-started any other way at least. Bypass or not it should start via starter, just remember to re-enable the safety valve for normal operation.
Hope this helps.