A sound Comes Out From Silencer

What you have is a back-fire:

http://en.wikipedia.org/wiki/Back-fire

Mike

Is your bike a two stroke? I never had a two stroke, but I thought they were not supposed to backfire unless there was something wrong and that it was bad for the system.

Drew

It may be after burn effect in the silencer.

The unburnt fuel will get accumulated in the silencer and burst once the condition is reached. You may have to ceck the carburation.

Generally this complaint will be more in hilly terrain in early morning.

Hi... Hemant here,

No this is not a normal situation. Your engine needs to be tuned. Usually in case of two stroke engine this bomb blast noise is due to misfiring of engine. When you are speeding the bike and suddenly reduce the throttle, some unburnt fuel gets out thru exhaust due to mistiming of engine and comes in contact with atmospheric air and combustion takes place in open air making bomb blast kind of sound.

Once you get your engine tunned. this problem will be solved.

May have an exhaust leak contributing to the problem of an badly tuned engine. Take to the shop guy for a spin-up.

If it is old vehicle and silencer is not regularly cleaned, the carbon deposits at certain portions of the silencer will act as a hot spot and burn the unburnt fuel inside the siencer during deceleration. I think of this because the bike would not have had this problem when it is new.

I am wondering if there is some form of fuel cut off valve that is maybe stuck open.

What happens is when you are "over running", you don't need fuel or ignition and both are cut off (to make the car/bike more economical), if the valve is not shutting when it should (assuming it has one, then fuel/air is reaching the hot bits in the silencer (muffler) and expoding...

Just a thought.......but I do not know if your bike uses such a system....

Called a backfire, combustion "leaning out" under those specific conditions, open out pilot screw 'bout a quarter turn at a time and test again. May need to lift needle also. (4 stroke) I had the same problem.

Presuming your Suzuki is a 4 stroke, it sounds if your running lean. If your bike is relatively new, the factory sometimes sets them up that way to help with emissions and such. A factory lean setting doesn't really hurt anything unless the backfires become excessive but a little tuning can make it a much more enjoyable ride. Reference madness's comments on tweaking-just keep track of how far you move your air screw.

Other causes could be an air leak in either the exhaust or the intake (easy fix) or finally the valves could be in need of adjustment(little harder if you've never done it).

My bike is 4 stroke, only 4 months old and drived only 3000kms. So it is cleared now that it needs to tune up.

Or an exhaust leak near the engine can cause this type backfire too. Make sure the exhaust pipes are fastened well.

Take it back to the dealership. Unless you have installed an aftermarket race pipe It should not be backfiring. With an aftermarket pipe, my UK version CBR 600 (pictured in avatar) likes to pop and crackle a little on decel after rolling off throttle. But that is not excessively loud. I put the stock silencer on because my Micron was just too loud for residential use. Now she purrs like a kitten and almost zero crackle.

Drew