Need open engine?

hello everyone, I bought my LTR 1 year ago, it's from 2008, it has athena 450 and Hotcams kit. so the quadricycle is going well... until a few weeks ago.... It makes me a little smoky and smells like oil, I've been checking the air box and it's dry. So I think the problem is inside, I don't know how it is, do you think I should open the engine? I removed the exhaust pipe and checked that there is a lot of coal is it normal?.. ... there is also a symptom that when accelerating it does not fire immediately only after 1,2 seconds... i will also check the throttle
I will leave some photos.