We are shocked read my review this is wonderful Honda CB Shine SP Honda hasn’t mentioned seat height of CB Shine SP in its technical specification, as per users review seat height of this bike is around 80 cm.As per user reviews mileage of Honda Shine SP in city riding conditions is around 50 kmpl while on highway it is 60 kmpl.There may be many possible reason of engine making heavy sound like, IC igniter trouble, carbon built up in the combustion chamber, fuel quality might be poor, some problem in the spark plug etc.; I advise you to take your bike to your local Honda service center for proper solution.it is very nice bike one time you drive it.