Horrible shaking and wobbling

[bop12]

Hi,
I hope I finally found forum where I can find answer for my problem
I have Chinese scooter Maxon Matador 125 (GY6). Scooter is approx 4-6 years old and have any 1500 miles.
When I ride around 30-35kmh it starts shaking and wobbling really hard. I can barely see something in my mirrors. My hands are like under 10kilo volts..
What could be issue?
Additionally, my maximum speed is about 40-45 and it shouldn't be problem as far as I read, to reach 50-55 mph.
Could you please help me what to check?
Thanks a lot!

[sc00ter]

Check the tire pressure.
Put it on center stand and raise the front wheel. Spin free?
Wiggle both wheels, and slop or strange movement?
Front tire look ok overall?
With front wheel off the ground, any movement/looseness in the headset?
Move bars forward/backward and lift each side up and push down.
On center stand, spin the rear wheel same as above.
There is a slight chance the front tire has a "flat spot" if its been sitting for any length of time. Cars will have it happen, but I dont recall seeing it happen on scooters.
Has the scooter been wreaked/crashed? I've seen dings in rims before and they will cause a shake. Bent forks will cause weird handling also.
If the front wheel spins "tight" without the brake being applied, its possible the front brake caliper is dragging on the rotor, and the rotor is warped.
Seen people ride on the very back of the seat and that will cause strange handling.
Good luck and share your findings.

[sc00ter]

You could also have a slipping transmission belt. That will sometimes shake the scooter while slipping during take off and be a cause of your lower top speed.
Anyone doing burn-outs on it?
Belts do wear-out but you scoot has low miles. Pull the transmission cover and look for excess oil and anything weird looking.

[bop12]

Hi, thanks for both answers. Tires are okay, same for wheels.
I would connect this problem with limited maximum speed and therefore I suspect engine or something similar.

[bandito2]

Steering head bearings, wheel bearings, engine mounts/bushings and front and/or rear shocks or even possibility of broken or cracked frame could also be suspect.