I have a tickin noise on a 250x could it be the cam chain?

 

It probably is, the chain is probably streched out, or, the valves are too tight, or a combination of both, I would take it to a pro for a rebuild.

 

Is there a way to tell if the chain is stretched

 

Not really, the only way is to put the old chain side by side with a new chain. Of course, if its longer than the new one (even by a little bit), it needs to be replaced.

 

Could be a rocker arm. Where is the noise coming from? If it goes away or gets quieter when warm, it probably just needs a valve adj. If you adjust it and still have the tick, it's probably a worn rocker arm or a worn cam or both. Both are moderate DIY jobs though.