I am needing some help on finding a replacement belt for my 2015 z force 800.  Has anyone replace there's with one that is not oem? And what would you recommend? 

Gates, work just fine.

[2015 Z Force 800 53/Trail EPS]

Yeah I think when it's my turn, I'll try a gates. There's a thread on them here but just go to their site and look it up.

Thanks for the info.  I got 1200 miles on the machine and not sure how long the belts last but want to get one just in case

These machines seem to be a bit hard on belts.  If heat is kept below the belts threshold I have seen guys get 3k miles out of them on other machines.  Heat is the real enemy on a belt.

Heat is your enemy and that's why this has been problem solved by a UTV racing team competing in the Score series in Baja Mexico racing up to 1000 miles in the desert. Control the heat in your belt and you extend its lifespan & mileage greatly. You can now control how hot your belt gets.
There's three options, the first one is a simple belt temperature gauge that lets you know that your belt is getting too hot. You don't carry on driving when your engine temperature is hot and you shouldn't when your belt is hot too. The belt temp gauge works with any ATV/UTV that has a closed clutch cover, it does not work for a vehicle that has an open clutch cover. You always install the sensor in the exhaust side of the cover. The Belt temperature gauge is $149.99 + shipping.

The second option is a CVT Belt Cooling System & belt temperature gauge that works with your your existing inline blower. Once installed it's the same principle as your radiator fan. The fan is controlled by the gauge and can be adjusted to turn on at any temperature you would like. This includes a Belt temp gauge with fan controller, complete wiring harness pre-wired with relay & instructions and stickers.The Belt temp gauge with Fan Controller is $239.99 + shipping.

The last option is complete CVT Belt Cooling System including Belt temp gauge with fan controller, 240 CFM blower fan with couplers and clamps, complete wiring harness pre-wired with relay & instructions and stickers. This is a complete belt care solution. With this kit you get a belt temperature gauge that controls a blower fan. The gauge has a light to let you know your fan is running. Also the gauge will turn the fan on and off at any temp you choose. Typically you have it set to turn on at about 140 degrees. The Complete CVT Belt Cooling System IS $289.99 + shipping.
More here/ http://www.pacificeagleutv.com/alba-save-your-belt