In the last week ort so, my bike has started to sound like a bag of spanners. Really rough and backfires like there's no tomorrow. Being the mechanical numpty that I am, can anyone point me in the right direction? For those that don#t know: it#s a Hondavtr. Garage suggested to take the engine apart and replace what's needed. I am leaning towards that as the bike has done nearly 50000 miles and in the last 34000 has only had one major service. So, anyone got anything sensible to say about the backfirey stuff?