Modern Vespa

I would like to lower the engine to make it easier to change spark plug on my LXV. Where do you support the engine when the rear shock is disconnected. When the bolt is removed the engine can fall too much without support.

Leave it on the centre stand, and it's just fine. It doesn't swing one way or the other without help. So undo the shock, and lift the frame up from the back. The engine will swing round enough to make it far easier to get to the spark plug. Disconnect the HT lead first though so as not to stretch it. A 19mm wrench is ideal to pop off the spark plug cap.

The method robot uses, the small platform jack to lift the body just in front of swing arm is the easiest way.

Like this one. It enables you to manage the angke of the engine quite well.

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Previously I removed the bolt at the end of the shock and the engine wanted to drop so I felt like i needed to restrain it from below to keep it falling too far. I'm just not sure where to block it.

You have left the wheel on? It'll only drop to where the wheel hits the ground before you start lifting up the frame at the back. Take the wheel off, and it might drop a bit further, but it doesn't go far. If you're twitchy about this (and I was first time) chock up underneath with some 2x4s stacked up. The centre stand supports the engine weight just fine.

So instead of putting the spark plug wrench from the tool kit or a swivel spark plug socket on the plug, and removing the plug and replacing the plug, (about twenty minutes work), you first want to drop the back of the engine, then R&R the plug, then raise the engine back up?

Why?

Fat hands and time to do it? Any excuse to stay in the garage with a beer?

It may not be the quickest way, but it doesn't take much extra time for those scooters with a single LH shock.