liquid cooled 4 stroke vs 2 stroke

[hockey4life]

I've heard things about the liquid cooled 250 4 strokes and how they can be very loud. I was wandering if any one knew how loud these are in comparison to a 125 2 stroke. If any one could post db readings and maybe a way to quiet down either of them without sacrificing performance please do. All feedback is greatly appreciated.

 

[hockey4life]

I've heard things about the liquid cooled 250 4 strokes and how they can be very loud. I was wandering if any one knew how loud these are in comparison to a 125 2 stroke. If any one could post db readings and maybe a way to quiet down either of them without sacrificing performance please do. All feedback is greatly appreciated.

 

[CRfury]

The four stroke will deffinitly be louder but it will be a low sound not a high pich like the 2 stroke. I find the four stroke less offensive of a noise but I love the noise of two stokes.

 

[Joepro9]

i dont think how its cooled has anything to do with it. I believe yhe decibles are 95 + since the fmf Q is 93.

 

[Lissa]

The 4str is louder; and with one of those wide open bazooka exhaust systems, its beyond retarded obnoxious! I find neither offensive with a FMF Q' series silencer or a properly placed rag in the exhaust. The Q' series silencer affects the power less then the latter mod.

(':laugh:')

 

 

 

[beer_stud_76]

hockey4life -

this is just my impression, but, 4 strokes and 2 strokes make a similar amount of noise depending on which exhaust is on a given bike. 2 stroke noise tends to be higher pitched, especially for the small bore engines, while 4 stroke noise is deeper, especially for the bigger bore engines. so the noise of a 4 stroke 250 might be the same at the tailpipe, but because it is deeper, it will carry further than a 2 stroke 125 (deeper pitch sounds waves travel further than higher pitch ones).

i'd guess that stock YZF250s and YZ125s are within 2db of eachother, but because of the difference in register they may not sound like it.


jeremiah

 

[demographic]

Originally posted by beer_stud_76
hockey4life -

this is just my impression, but, 4 strokes and 2 strokes make a similar amount of noise depending on which exhaust is on a given bike. 2 stroke noise tends to be higher pitched, especially for the small bore engines, while 4 stroke noise is deeper, especially for the bigger bore engines. so the noise of a 4 stroke 250 might be the same at the tailpipe, but because it is deeper, it will carry further than a 2 stroke 125 (deeper pitch sounds waves travel further than higher pitch ones).

i'd guess that stock YZF250s and YZ125s are within 2db of eachother, but because of the difference in register they may not sound like it.


jeremiah

Bear in mind the sound is measured on a logarithmic scale so even a 2 decibel difference is a massive amount of extra noise

 

[viking20]

In this country we measure the noise at the source,-bike under full load.
When the track is inspected every year,a measuring point is selected,typically a long straight.The track has to have a marshall who measure the db level at every practice,if needed.At local races youll sometimes have the official people turn up,and at every National event they will always be there,testing the noise level of all the bikes.The max levels:
Micro 50(polini,PW 50,etc) 111db,Micro 80(PW 80,SUZ ds 80,etc) 113 db
Mini 65-85 121db,
125 128db
250 128db
500 124db
4-strokes 129db
Many bikes struggle even with standard silencers,but with fresh,correct packed wool theres rarely problems.
The sound of a 4-stroke is not necessarily measured louder in db´s,but a neighbour to the track will almost always hear the 4-strokes louder.Its just like listening to loud music at a distance,you only hear the bass notes,and the bass drum.

 

[GeoffM24]

They are horribly loud. I hate riding with 4 strokers because I can't even hear my bike and I have a 250 with a shorty silencer.

 

[Joepro9]

just pass him, then he has to put up with your sound. ;)

 

[viking20]

With nearly all of the tracks in this country having problems with the noise,its not a case of the 4-strokes being the "future of racing",they can very well be the end of racing instead...... :ugg:

 

[Joepro9]

they say 2 strokes polute, but so do 4 strokes, noise polution. that would be a perferct argument for that problem in Mass. with the housr will 1909 or whatever...

 

[demographic]

Originally posted by viking20
With nearly all of the tracks in this country having problems with the noise,its not a case of the 4-strokes being the "future of racing",they can very well be the end of racing instead...... :ugg:

Exactly