Cooling down Noise in the silencer when the bike is switched off?

[rennycornelius]

After a ride of about 10-15 kms or even less in my APACHE RTR FI, when i switch the bike off the silencer starts makin a "kat" "kat" noice.......

the same noice my HONDA DIO also used to make,i experienced this in the bikes sporting the black end cans only(CBZ,RTR,P180,DIO).....

one auto mag also clarifies this as the "cooling down noice" of the silencer...............

any ideas whats this noice is all about........????

[Aryan]

Thread approved and moved.

I don't have much idea what's happening inside the silencer/ exhaust system but even my P-200 makes this noise, but strangely the P-180 Classic did not emanate this noise..

[yamracing]

Some metals, when cool, make such sounds. This is completely normal, and nothing to worry about

[Old Fox]

All metals expand when heated and contract on cooling and metals in sheet form do this all the more and quicker too because of the larger surface involved. Since exhaust pipes are invariably made from sheet metal which heats up while the engine is running, it cools and contracts rather rapidly once the engine is off. This contraction makes the 'kit-kat' sound. All pretty normal.

PS: check out a similar sound from your electric iron once you switch it off

[Technocrat]

I got this noise in all my bikes i.e. P180 DTSi V1(chrome silencer), ZMA & RTR except for the classic 150(which i didn't ride fast )

From what I remember its the sound from the Catcon in silencer which is due to contraction.

SO all the bikes with catcon will have this sound & the older ones without catcon wont

[rider_richards]

thats a just normal bro...

lets keep on riding..

[winzeee]

Zma make the loudest noise i guess BTW no worries its normal .


W

[Puneet1]

2day il check if my bike also mkes this noise . i thought only cars make it cos my maruti also used to have tak-tak sound

[SARAB_FI]

this kat kat noise is coming frm the engine side in my bike (guess its the cooling of engine tappet).

regards
sarab

[sameer_hyd]

@Oldfox: Bang on.......Uneven expansion of solids....more so, the part of the silencer near the engine is hotter than at the end of the silencer.....So more the heat, more the expansion...

[Technocrat]

Its from Silencer & not from engine

[sam92]

its just expansion and contraction ..
no need to worry ..
even i had the same doubt ..

[rennycornelius]

All metals expand when heated and contract on cooling and metals in sheet form do this all the more and quicker too because of the larger surface involved. Since exhaust pipes are invariably made from sheet metal which heats up while the engine is running, it cools and contracts rather rapidly once the engine is off. This contraction makes the 'kit-kat' sound. All pretty normal.

PS: check out a similar sound from your electric iron once you switch it off

ya that elec iron thing was right......!!!!!
it made that kinda noice too..........

[inimaitimepass]

After a ride of about 10-15 kms or even less in my APACHE RTR FI, when i switch the bike off the silencer starts makin a "kat" "kat" noice.......

the same noice my HONDA DIO also used to make,i experienced this in the bikes sporting the black end cans only(CBZ,RTR,P180,DIO).....

one auto mag also clarifies this as the "cooling down noice" of the silencer...............

any ideas whats this noice is all about........????

i guess it is a common thing in the air cooled bikes... there is no prob regarding this... its very very normal... since the metals expand in heat when turn off the engine, the heat will be reduced gradually thus the metals contract.... apply basic physics here.... but that sound will not come all the time.. u can hear that occasionally after long rides...