..... which can be caused by a badly stretched cam chain. The chain stretches gradually over time, just like a drive chain. Your adjuster is spring-loaded and compensates plus you re-set it from time to time so you may not notice any wear by looking at the adjuster. It won't plainly show you excessive wear like looking at the chain adjusters on your rear wheel would.
47K is quite a lot for an original chain. I'm sure they could last that long or longer if properly maintained but there's the rub. You should check and adjust the chain if necessary about every 1000 miles. Most of these bikes never received service like that. Original chains are usually toast by about 20K.
Check your timing at full advance with the light. As I said, that's important, more important than where it falls at idle. I'm suggesting you open the gaps back up a little. They may be too small now. Just don't make them as big as you had them (.35mm) because then you can't get it to time right.
47K is quite a lot for an original chain. I'm sure they could last that long or longer if properly maintained but there's the rub. You should check and adjust the chain if necessary about every 1000 miles. Most of these bikes never received service like that. Original chains are usually toast by about 20K.
Check your timing at full advance with the light. As I said, that's important, more important than where it falls at idle. I'm suggesting you open the gaps back up a little. They may be too small now. Just don't make them as big as you had them (.35mm) because then you can't get it to time right.