Px health check

Im new to scooters so forgive any stupid questions as Ive had nothing to compare my scoot with. I want to test the compression on my second hand px125 as I think its suspect. Can anybody tell me what the compression (psi?) should be on a healthy engine? and can anybody recommend a good compression meter for the job, and the way to do it.

Also, my px smokes alot (white smoke) when I start it up in the morning (it lives outside) with choke out. As soon as I drive up the road a few seconds it clears up. The engine idles a bit rough, and the lights flicker at idle. There is a very slight amount of play when grabbing the flywheel and pulling it from side to side. When the engine is in neutral and the bike is parked, on revving the engine to high revs a wobble can be felt through the engine and frame. When driving the bike high frequency vibration is felt through the footboards and handlebars.[:shock2:]

Cheers. Ed. [:look:]

Hi Ed I`m not an expert but I try to do some hypotesis:
The compresion ratio in Px 125 is 8.2:1 (in E model is 8.5:1).
About white smoke:
Beware about fuel mixture, my be incorrect. Or may be oil rest in exhaust system. Or the carburetor may be dirt.
About vibrations, check the stering column, and fork. Also Check the shockabsorbers.

I hope this help you[:P]