Motorcycle Repair: Yamaha, yamaha india, clutch cable

Question
Hi,
  I have a Yamaha(India) 125cc Enticer vehicle a 2003 model. The problem is that I cannot accelerate it more than 70kmph. From 60+kmph onwards it gives terrible sound, it appears to me that the engine is not able to deliver the power. This was not the case with my earlier 100cc bike even if I accelerated to speeds of 90+ too. At speeds less than 60kmph the bike is really smooth.I brought this to the notice of the company engineers but they have failed to slove the problem and infact they do not agree that the vehicle has any problem. I am interested to know what could be the problem so that I can atleast get the vehicle repair with a private mechanic or could even follow it up the company engineers. I would appreciate u'r replies. Thank u  

Answer
Hi Uday,

Check condition of spark plugs. Check for air intake restrictions. Check clutch cable adjustment and clutch plates wear.

Otherwise, I would need to perform several checks to accurately diagnose the problem.

Respectfully,
Mark Shively