Modern Vespa

hi i have a piaggio fly 125 which has done 4400 miles and was owned by an old lady never crashed or anything but was stored for a few monthes has not seem to cause any problems,but have noticed a slight wobble on the rear tyre.if you have it on the stand and accelerate you can feel it cavatate and makes the bike shake and movem,if you release pressure slightly when riding you get the start of a tank slapper.i have always had hayabusas and can do all work on them but this is first twist and go.can anybody give me an idea how to cure this or give ideas .cheers chris

Things that may cause a wobble:

Bad tires
Improper air pressure in tires
Tire out of balance(may have lost a weight)
Worn or improperly torqued steering head bearing
Worn swingarm bearing/bushing
Worn wheel bearings
Worn or improperly adjusted suspension

These are the ones that I remember off the top of my head. There are probably more. I hope you get it figured out.

Check the engine swing-arm bearings. With the bike on the centre-stand, and a helper keeping the frame as still as possible, try to move the whole rear wheel and engine from side to side. There should be virtually no movement. These are needle-bearings that are hardly greased from the factory.

thanks for reply.the bike was full service history and was serviced 50 miles before i got it and have checked all movement etc on bearings and steering its on the rearjust cant sus what is causing it.maybe standing up for a while has warped the tyre,it doesent feel like weight on wheel have had that a lot and feels diffrent.will let you know if i get an answer.any info will help.like i say always been big bikes and all my kit is set for them not scooters,engine is stable and wheel seems ok for movement just did not know whats inside that may cause this.cheers lads.chris