Motorcycle Safety & Driveability: Motorcycle engine vibrations, and some other doubts., air fuel mixture, honda cbf

Question
Hello, I am Jagadeesh from India.  I own a Honda CBF Stunner (carbeuretted version of cbf125).  My motorcycle has completed two free maintenance services recently.  During the second service, the company mechanic messed up somethings.  When I was taking it home from the service centre, first the bikes rpm was not coming down as if the throttle was stuck, so i took it back to him.  He adjusted the idle speed and the cable and I dont know why but he also turned the petrol-dry screw(as he called it) on the carbeurettor and reset it.  Then another problem began, the petrol was leaking from the rubber tubes that were attached to carbeurettor constantly.  I took it back and the mechanic removed the carbeurettor, cleaned it and re-fit it.  Since then, them mileage has increased very unusually.  which was once around 65km per litre, is now above 75kmpl.  The engine has been overheating a lot, and struggling at speeds above 60kmph. I travel to my office which is about 50 km from my home thrice a week, this problem has been bugging me for some time.  Could you please guide me about what I should be getting done with the bike and solve the problem.  Another problem is the bike vibrates at a specific rpm range(i cant tell you where since it has no tacho) in every gear and there are no vibes above and below that rpm.  Mostly i have experienced the vibes at 63-65 kmph in 5th gear.  The bike does have shorter gear ratios than the FI version i.e., the CBF125.  Please do guide me how I can rectify this vibration problem as well.

Thanks in advance.  Please do reply.

Answer
I had to look up the specs on your bike since it is not a model that is sold in the U.S. It is a very nice looking bike.

First, let me say that I am not an expert on mechanical issues. The symptoms you describe however lead me to believe the air / fuel mixture is not set correctly. That could be the cause of the overheating problem and may be one reason why the fuel mileage has increased. I suspect the mixture is set too lean, meaning more air than fuel causing the overheating problem. I suggest you get a qualified mechanic to look at it as soon as possible to prevent damage to the engine from running to hot.

I have conducted a google search for owners forums for the Stunner and found a few interesting comments. It seems you are not alone having a vibration problem.

Here is one discussion:
http://www.consumercomplaints.in/?search=honda%20cbf%20stunner

I suggest you look for an online forum for Stunner owners. I have found through personal experience there are usually some very knowledgeable people on the forums offering advice specifically for your model motorcycle.

I hope you find this information helpful. I'm sorry I cannot give you more specific advice.

Thank you for the question.
Regards,
Tom