Bike motors in quads

[250Renvy]

How come when people want to put 2-stroke bike motors in quads there is always the issue of vibration, but I've never heard of people complaining about vibration with 4-stroke bike motors in quads.

Is vibration still an issue? If not why?

Looking to do a XR 400 motor in a 250R custom frame or possibly a CRF 450X motor.

Just exploring all options.

[trx250r180]

4 stroke bike engines have counter balencers like quads,2 stroke bike engines dont ,non counterbalenced rev quicker,counterbalenced have more tourque,i lost my counterbalence bearing on a dune trip once and just took it out and was able to ride the rest of weekend,but it vibrated bad,waterpump also was lost because balencer drove it ,but i never overheated too bad ,some flattrackers used to remove em for faster revs