I picked up a 09 SRA foot shift fourtrax 420 off a farmer. Bike has 25,000km and 2300 hours. The engine has a pretty good tick to it. I started out with a fresh oil change and a valve adjustment. Some of the noise went away but not all. I then did a compression test and it came back at 125psi. I ran sea foam through it to help get some carbon build up out. It then dropped down to 110psi. Which I assumed is where it should be? After that the engine quieted down, but it still has a noise coming out of the cam area.

Are the cam chains know for wearing out and becoming noisy? The tick is more noticeable on hard acceleration and when you let off the throttle. I’m leaning towards cam chain or wrist pin. But would like to narrow it down before taking the engine apart.

Thanks for the pointers, and yes it has 25,000km on it not 2500.