I have oil in the Air filter and the engine is seized. My son was riding it said it was blowing blue smoke. Guessing the engine is gone. any idea on how to get a new engine?

More details of your machine please .

Mileage?
Stock air filter ?

A frozen breather can cause that but I suspect a faulty air filter.

Where are you from.
I know a shop here in Quebec that have a low mileage engine.

[2015 Z Force 800 53/Trail EPS]

Sorry to hear of your troubles. You can buy complete crate engines from your local dealer and also have them install if needed or from Alpha-Sports.com and do it yourself..or get all necessary to rebuild it from them too. You can also send that engine to my friends at nFlow for a complete reman. Give them a call for a price. Here's their web site:

https://www.nflowmotorsports.com/