Modern Vespa

Installed a freshly charged battery on my winterized 2020 Sprint 150 (2500 miles on it) and started it up. It takes a few seconds for the engine to start when cold, maybe about 3 to 4 seconds turning before ignition catches. Not sure if that's just the cooler temps and some condensation in the line (about 35 degrees this time of year) or a problem somewhere in the ignition/starter system. Starts up quickly once warmed up. I'm going to change the spark plug, because it's a cheap and easy first step. Any advice would be helpful. Otherwise I've got to run it across town in the cold to my dealer for a tune up.

My 2019 Primavera is a little slow to start too, when it's cold. It improves when the weather gets warmer, above 40F or so. I doubt that you have a problem in the ignition or starting system. I'd give your scooter a little more time before taking it to the dealer.

What did you do to winterize it?

Thanks, yeah I hope it might have more to do with the temp than the bike. As for winterizing, I changed the oil, added fuel stabilizer, filled the fuel tank to prevent moisture forming, added air to the tires, removed the battery (I keep it charged indoors), and gave the bike a good wash and wax. The bike is stored, covered, in an unheated shed so it gets pretty cold sitting there.

Yep, sounds like you have a good winterizing routine. I doubt that anything happened over the winter that would cause the scooter to start harder. I wouldn't worry -- and hope for some riding weather warmer than 35 degrees!

I rode a few times when it was in the 30s and my GTS was also a bit slow to react when stone dead cold.

I'd not read too far into it until it's consistently warmer. If it still struggles in the high 40s/low 50s, may be a good idea to get some more in depth investigation going.

Maybe thicker/colder oil just takes a little longer to get into the system and create good pressure for starting.

Good idea. Yeah, even on warmer days this time of year, it still gets close to freezing at night. Lord knows how that's affecting the spark plug and fuel line on the first start. I'll wait it out.

The cold does not affect the spark plug nor the fuel line. It is the fuel.

The engine needs a mixture of air and enough vaporized fuel to ignite. When the engine is cold the fuel has difficulties to vaporize. And the colder it gets the more difficult fuel vaporizes.
That is why it may take several rotations before the engine ignites.
Once ignited the interior of the engine warms up fast and no more vaporizing difficulties.

Thanks mate. That's a helpful explanation.

That and the crankshaft has to travel 720 degrees between power strokes. Whereas even a four cylinder vehicle crank only travels 180 degrees.