I just want to say there is not much info on troubleshooting the SSR XF250GY so I am trying to start an info cache here.
First, The gas tank rusts on the inside which causes problems for the fuel system. if your bike is acting like it is running out of gas or wants to die when you move it around such as pushing it, the rust may have made its way to the carb or the petcock screen is clogged. Best to put an external see through fuel filter so you can see when it gets dirty. There is an emission line under your tank in the very center that runs to a port on the right side of the carb this can get clogged as well and give you many problems. Best to leave this line on gas tank and run a new line from carb hooked to nothing to let the carb breathe. Then, clean the carb, gas tank, and petcock very good. you can buy a gas tank liner that is like the plastidip for tool handles that will coat inside the tank. if you take the top of the CV carb apart there is a rubber housing that is hard to get back in place to seal it so i don't recommend taking top of carb apart if you are newer to this type of thing there is not much there to clean anyway.
second, it is very easy to adjust the valves on these bikes the specs are on the front left side under tank on frame get some feeler gauges and make sure these are in spec so the engine lasts longer if you need help just message me or this thread.
third, there is not much saving the chain from cracking your case if it breaks so keep your chain in great condition at all times to help avoid this problem. the back brake pedal can also crack side of your case if you lay it down I recommend adjusting it so it is not so high up by the case. Also, you can have a bigger engine guard made by any fabshop that will help protect the engine as well. They are easy to make if you know how to weld and have the tools.
In conclusion, Keep up with the maintenance and these bikes are awesome. Please if you have any experience with changing parts or where to get parts for these bikes post them here so we can educate ourselves. http://www.chinesemotorcyclepartsonline.co.uk is a great place for parts just wish there was a place like this in the US.