Timing chain stretch

[Stinky]

On my '86 Yamaha 250 Timberwolf (actually a 230, if I remember right)...I took it to a place to get the carb working right and valves adjusted.  It clattered.  I thought that it was loose valves.  I had those adjusted and they said that they weren't bad and that he thought that it was the timing-chain, and that they do stretch.

I don't know the age of my motor, it does smoke a bit, but runs fine, although it smokes a tiny bit.  

So, assuming that it is the chain....anything that it might rub against or damage.  Should I worry about it?

 

[Kraut_n_Rice]

Does it have an external tensioner?  Maybe it went bad.

 

[1HasBeen]

Aside from what has been mentioned, not sure on your model, but on some of those older Yamahas the cam rode on a roller bearing and I have seen them fail and cause noise and inability to hold proper clearance.

 

[Stinky]

Going by the sound, it sounded like sloppy valve clearances.  And, only when at an idle.