KymcoRider

Hi All - My First Time Posting. 1st I have a Kymco Pulsar S 125 its a 2014 model i brought it 2 years ago second hand it was running great up until 3 months ago when i started noticing it started to Jigger when i was in 4th and 5th going steady around 40 in 4th and 50 in 5th i have also lost power it used to go 60-65 mph but now it just hits about 50-55. 2nd I also had 2 pipes burn out so i went out and replaced them because i was told they probably just gotten brittle over time. Today 23.08.2017 the new pipe that had been replaced 2 weeks ago burst again and inside the pipe its hard and brittle were its gotten to hot. please can you have a look at the 2 images and let me know what could be causing the problem and if it would be a easy fix Thankyou. http://imagizer.imageshack.us/v2/1024x768q90/924/eGDdCx.jpg http://imagizer.imageshack.us/v2/1024x768q90/923/VLQruF.jpg