Check your bike compression through compression meter,
Goto the mechanic store where those meter available to check your bike compression reading, if it do not match with standard reading in psi I forget what exactly is, Then your bike head having issue, Off course bike head contain can shaft, rockers, valve and seals and some other small Components that can be check once you found only if compressor reading isn't match with standard or near by, also check the breather pipe, it might be chowk or block, Very little work, Just goto mehcanic and ask him to show you the breather or air pipe, Ask. Him to. Show if it chowk then clean it, Then let me know what result come, If compressor or down then you have to see the head cases is the latest one which cool the bikes through their ziczac designs or the old one, Sometime it needs to be look or change after checking the components fault inside the head
