DB KILLERS

[Two dogs]

Gday OZMonsters,
A mate of mine just changed his pipes to a two into one
with the result of less power output
so this got me wondering about back pressure and its influence on HP output.
Has anyone ever done a Dyno on there bike with and without DB killers
aka baffles
Been a wondering if they have an effect on power output with extra back pressure

[Justo]

Ive been wondering the exact same thing. Seems to be alot of opinions, but no graphs showing the results... Did you find anything on the interweb regarding this.

[dragonworld.]

Of course this is all theoretical as your power output, and when and where in the rev range it is produced is all to do with engine design, cams, head work,valves, blah, blah blah. 

But to try and make a complicated story simple, backpressure will get you off the line better but wont flow as good as the rpm increases.

A freer flowing zorst generally means that a bit more throttle is required to get you moving but will allow your motor to rev harder up in the higher reaches.

The 2 into 1 might feel like its producing less power (probably toward the upper reaches of the rev range) but it more than likely is stronger (More torque )down low and pulls harder through the midrange. Is different pipes for different power, one type wont do everything.

In my old days of racing a yam 2 stroke, I had 3 sets of exhausts (Expansion chambers) that were all different and had different power characteristics, 1 set for low down power for short, twisty tracks. 1 set for high power, high speed tracks, and 1 set for better wet track power performance. [moto]

[loony888]

the biggest drawback with Db eaters is if everything else remains the same if you tune it without them then it will be rich with them. if you tune it with them it will be lean without them.
now, that's ballpark and how big a difference there is depends on the bike, but they are as close as you can get to having your cake and eating it. obviously, you need to have carbs or tuneable efi to alter the tune, best to try it with and without and decide what you prefer and stick with it, my preference would be to leave them out have it tuned to suit, if you get hassled, fit the eaters for an inspection then take them back out. of course, if your bike has a cat std and the cops know it, it's not going to get through an inspection without the cat so eaters won't be much of an advantage there.

paul.

[dragonworld.]

the biggest drawback with Db eaters is if everything else remains the same if you tune it without them then it will be rich with them. if you tune it with them it will be lean without them.
now, that's ballpark and how big a difference there is depends on the bike, but they are as close as you can get to having your cake and eating it. obviously, you need to have carbs or tuneable efi to alter the tune, best to try it with and without and decide what you prefer and stick with it, my preference would be to leave them out have it tuned to suit, if you get hassled, fit the eaters for an inspection then take them back out. of course, if your bike has a cat std and the cops know it, it's not going to get through an inspection without the cat so eaters won't be much of an advantage there.

paul.

But, but that wouldnt be leeegull now would it?? And of course Paul you wouldnt be advocatin' anything that would contravene tha laws that are designed to save us from our gratuitous and wanton desires to be antisocial, now would it??  [moto]

[Justo]

But, but that wouldnt be leeegull now would it?? And of course Paul you wouldnt be advocatin' anything that would contravene tha laws that are designed to save us from our gratuitous and wanton desires to be antisocial, now would it??  [moto]

So its actually illegal to have them removed?

And when you say illegal you mean Illegal like "running a stop sign illegal" or illegal "like jay walking illegal".

[ducatiz]

i am surprised no one has developed an aftermarket setup with an exup type valve.  it could be TPS actuated or just manual. 

actually, i should just do it.  efi bikes have the TPS right there, just tap right into it.  i gotta call my exhaust buddy.

[loony888]

But, but that wouldnt be leeegull now would it?? And of course Paul you wouldnt be advocatin' anything that would contravene tha laws that are designed to save us from our gratuitous and wanton desires to be antisocial, now would it??  [moto]

nowhere in this thread have i led anything that says it has to be "legal". the law is ALL loopholes anyway, so use em to suit your situation.


paul.

[Q777]

http://www.bikeboy.org/s4rsmonstertermikit.html has a comparison between baffles in and out...

[Two dogs]

Thanks thats exactly what I was looking for nice find Q777 

[Justo]

Lil story. Slightly transgressed but valid.

So the db on the termis are out. Ohhhh my deary me they sound awesome. Like the groan of Thor just before he cums. Um yeah anyway where was I. So I'm filling up at the servo at woolloomoolloo tonight and two cop bikes pull up harrys Pies for a coffee or a tiger pie or three.

 I go in and pay and come out and there is a patrol car at the bowser behind fillin up.

So I'm slightly nervous now With the legal thing playin in the back of my mind thinking these are loud.
Coppers every where. Well I start up. And ride out. The copper fillin up looks over and has this "that's mad" smile. As I wait for a gap in the traffic to pull out both bike cops are lookin over. I pull out and give the nod the I get a big from one of them.

Ha. I just giggled to myself all the way home.

Should be more of these coppers out and about.

Oh and to the chick in the smokin blue mini dress and knee highboots buying chewing gum. I'm sure no one cares if u have bad breath!!

  Anyway worth the mention. Still smilin thinkin about it.

[ducatiz]

Oh and to the chick in the smokin blue mini dress and knee highboots buying chewing gum. I'm sure no one cares if u have bad breath!!

she was a working girl, trying to get the taste out of her mouth!

[Betty]

It was Woolloomooloo, are you sure it was a girl?