making a shorty slip on

[bcleveland]

I was thinking about making my big gun es slip on into a shorty. Is there any advantage to doing it as far as performance goes. I am not worried about the noise just if theres any power to be made. Thanks

[ish416]

There will be no power gains at all, just more noise.

To anyone who thinks otherwise, prove it. Dyno numbers of before and after.

[TacicalRedneck]

I was told the TC shortys were pretty impressive- but i don't have any dyno sheets.

[JOHNDOE83]

Ericrip AKA 400exshop has the dyno that proves it.

Its a known fact that the more air it will let out and the more air it can take in, will produce more HP.

Thats why the aftermarket exhaust's make more power then a stock header or muffler "they flow more air".

The only motor that a tuned exhaust is needed in is a 2 stroke!

Monster trucks, Harley Davidson drag bikes, top fuel dragsters, formula 1 and nascars dont use slipons or mufflers for this reason.

[ish416]

Originally posted by JOHNDOE83
Ericrip AKA 400exshop has the dyno that proves it.

Its a known fact that the more air it will let out and the more air it can take in, will produce more HP.

Thats why the aftermarket exhaust's make more power then a stock header or muffler "they flow more air".

The only motor that a tuned exhaust is needed in is a 2 stroke!

Monster trucks, Harley Davidson drag bikes, top fuel dragsters, formula 1 and nascars dont use slipons or mufflers for this reason.

It's obvious that the more air and fuel you add to an engine will produce more power, and the more air and fuel you add the more you need to remove the burnt exhaust gasses. I am not questioning that. My point is, a straight thru design muffler is suppressing sound by using a perforated tube and packing material (sometimes also tunable discs on the end cap). Any resulting difference in exhaust gasses not escaping will be negligable to the point of likley not being able to prove any power gains at all.

Example: I have seen a flat track bike placed on a dyno with a muffler (2004 YZ450F with GYTR full exhaust *before the 99db sound level*) and then he removed the muffler, ran it again and amazingly, nearly the same number came up both on the power levels (-.1 hp) and the A/F meter (13.6 - 13.4 at peak power).

If a muffler made any difference then why don't I see more people riding around with no mufflers on fully built race bikes and quads when they are not required to have them?

[JOHNDOE83]

In the race world for harescrambles and woods racing a DOF approved spark arrestor is needed to race. You cant make one you have to buy a slipon that is speciffically approved by the DOF. Here in Florida anywhere that allows atv riding requires you to have a DOF approved spark arrestor.

Indoor and mx racing Im not really sure what the regulations are for exhausts, I know that when your mx or indoor racing being able to hear the guy behind you means alot. A loud header only pipe would just be way to annoying for that type of racing.

Like you said, the difference wasnt that much on a dyno. + or - 1 hp, my only question for that result would be was the jetting changed and how was it done? Im sure they may have changed it, but without the deffinet answer we can only speculate.
Basically if it were already to lean then you remove the slipon, it would read less HP, if it were to rich you wouldnt fully rev out and also get a bad reading, I know A/F meters wont allow you to get to rich, I know that they deffinetly will be leaner then they read.

I dont trust a/f meters on atv's and dirtbike's, stupid I know but I just feel theres no way to compare computer data to real world riding conditions. Here in FL its so humid if you tune something indoors, it will be way out of tune outdoors. The air is warmer, the humidity changes constantly, I feel like theres just to many options for change after A/F dyno tunning. 90% of people I seen dyno tune still pop and backfire and run hot.

If there were a ATV dyno around my area, I would love to go there and spend some time testing the dyno results compared to real world conditions and my www.jetsrus.com jetting procedure.

Where can we look up regulations for motor components for sanctioned racing? It would be interesting to see what kinda loop holes and tricks we can find:devil:

[Longdong]

Originally posted by bcleveland
I am not worried about the noise just if theres any power to be made. Thanks

I don't know whether it will make more power or not. I do know not all exhaust are =. Some new pipes you lose power. But I am 100% sure a loud exhaust is not good for the sport. All it takes is one pissed off landowner and that is the start of a regulation law. That is all it take for people to jump on a BANwagon. So please think about that statement. IMO

[bcleveland]

Originally posted by Longdong
I don't know whether it will make more power or not. I do know not all exhaust are =. Some new pipes you lose power. But I am 100% sure a loud exhaust is not good for the sport. All it takes is one pissed off landowner and that is the start of a regulation law. That is all it take for people to jump on a BANwagon. So please think about that statement. IMO
I understand what your saying. I only ride on my father in laws farm and its 1300 acres of let it rip. So theres not much of a complaint there. I do take weekend trips to diffrent trails every once in a while. I will still be able to use my spark arestor so I am sill good there. I have never seen db levels checked at any of the trails we ride in NE Georgia but you never know I guess.