Factory Sound performance characteristics

High Lord Gomer

Poked with Sticks
Sep 26, 1999
11,788
35
I ran a Factory Sound silencer on my 97 CR250.  It seemed to add some top at the expense of bottom end power.

I'm considering a Factory Sound silencer for one of the kids' KX80 and am wondering if it will have a similar effect on performance.

If so, which silencer would add bottom end power, even if it loses a little top?
 
M

mxer578

Member
Dec 30, 2002
4
0
not sure on a little bike but well its not little but an 80. i have an 02 cr125 and i have a pc pipe and shorty scilercer and the shorty for me added more bottom.i know bubba on his 80 had a shorty and i have freinds that have them on kx 85 and they love um cause they gave more bottom hope i could help :flame:
 
J

jboomer

~SPONSOR~
Jan 5, 2002
1,420
1
If you get more bottom from the shorty, then why do they advertise it as "perfect for SX?" You're backwards! :confused:
 

Okiewan

Admin
Dec 31, 1969
29,550
2,238
Texas
Excuse me folks...
Is this a "guess the answer" thread or what?

Shorty silencers are generally marketed as bottom-mid increases, thus the mention of SX. Think maybe bottom is more important on a SX track than on a MX track?

Just a thought... we might want to give the vendor an opportunity to answer the questions in their forum before all the speculation begins. Afterall, that's the reason the vendor forums are here.
 

MikeT

~SPONSOR~
Jan 17, 2001
4,095
11
Just latching on. I want to see what the vendor says. I have always wondered what the real scoop is with the long/short thing.
 

ProCircuit

Member
Jan 16, 2003
96
0
The design of Pro Circuit's Factory Sound Stainless silencer, the R-304, combines a dynamic round look with the latest in short construction, making it very innovative and versatile for specific types of riding (i.e Supercross). The superior construction of the R-304 effectively balances durability, and quality, making it an exceptional choice for those who desire a high-performance, lightning quick silencer. This silencer offers more bottom end power and snap off the bottom. Most riders prefer this for all applications (MX, SX, and Off-Road). They tend to like the low end power and are willing to sacrifice some top end.

The 304 features a longer midsection for noise conscious riders and more noticeable overrev. The 304 is excellent replacement for the OEM silencer while offering impressive performance gains.
 

MikeT

~SPONSOR~
Jan 17, 2001
4,095
11
Uhh, Could you talk a little about the long and short thing? Is this generally that logner does one thing and shorter does another? I know you said that your short silencer makes good bottom, but is that due to length, back pressure a combination of the two or what?

Thanks.
 

ProCircuit

Member
Jan 16, 2003
96
0
The Shorty silencer gives you more bottom due to the smaller canister. The longer body of the 304 Stainless gives you more overrev.
 

MikeT

~SPONSOR~
Jan 17, 2001
4,095
11
So that is because the smaller canister produces less back pressure, or is it for another reason?
 

ProCircuit

Member
Jan 16, 2003
96
0
There seems to be a misconception on the performance of silencers. I would like to set the story straight. The Shorty silencer is designed with a short canister which adds more bottom end power than the 304 silencer. This doesn't mean that it might not add more top end power when compared to your stock silencer, but it has more bottom than the 304. Now, the 304 silencer is designed with a longer canister body which gives the rider more overrev than the Shorty silencer. Again, this silencer could add more bottom end power than your stock silencer, but it has the most top end bottom when compared to the R304 Shorty silencer.
 
K

kdxsam

Member
Sep 20, 2002
101
0
How come Pro Circuit doesn't make a Shorty silencer for the KDX200? You'd think it'd be a great idea because it gives you good bottom end in the tight woods stuff. I've got your Platimum Pipe and the new Race Cap 304 silencer on my 2001 KDX200. I love this setup! You guys are really great! I just wish that you made a shorty version for it! I'd buy it in a heartbeat! Well, it's an idea for ya?
 
S

Studboy

Thinks he can ride
Dec 2, 2001
1,818
0
I think that the reason they don't make a shorty for the KDX is because the KDX is a TRAIL/WOODS bike and the  noise that the shorty makes is excessive!  :think:
 
K

kdxsam

Member
Sep 20, 2002
101
0
Well, that may be true. But, I love the sound of Shorty's!!! They can't be that bad! You don't actually need a spark arrester in the woods. I'm just putting in my personal opinion.
 
S

Studboy

Thinks he can ride
Dec 2, 2001
1,818
0
Originally posted by kdxsam
You don't actually need a spark arrester in the woods. I'm just putting in my personal opinion.
Click to expand...

Not unless you like getting busted. :|

Don't worry,  with that shorty the forest service guys will hear you coming from miles away.
 

ProCircuit

Member
Jan 16, 2003
96
0
The reason we never made a shorty for the KDX200 is because sales for KDX200 product is very low. Kawasaki doesn't make a lot of these bikes and there is not much demand for the shorty for this model. Also, another reason is the Shorty application came about due to Supercross...which explains why most of the models are for bikes rode in the AMA Supercross. Sorry!!!
 

nephron

Dr. Feel Good
LIFETIME SPONSOR
Jun 15, 2001
2,551
0
Okay, I'll ask the question a 3rd time. No offense PC, and I know your time is limited, but please venture over to the mods/perf. or advanced technology forum and take a look. There are some intelligent people on this board that deserve intelligent answers.

Can you please comment specifically on silencer length and core diameter as they might relate to tuning? Please include, eg, something about pulse wavelength and/or exhaust timing events in the discussion.

I'm not feigning intelligence or trying to be rude, just curious how the bigboys do it. :thumb:

Thanks.
 

nephron

Dr. Feel Good
LIFETIME SPONSOR
Jun 15, 2001
2,551
0
 :think:
 
S

Sage

dirtbike riding roadracer
Mar 28, 2001
621
0
Shorter over all exhaust length will result in the cylinder pressure wave returning to the cylinder at a lower rpm because it has less distance to travel through the exhaust system resulting in exhaust scavenging at a lower rpm (more bottom end). A longer exhaust length will return the pressure wave a bit later resulting in cylinder scavenging occurring at a higher rpm (more top / over rev).

That’s the idea in a nutshell behind the shorty and the std 304, hope it helps.
 

ProCircuit

Member
Jan 16, 2003
96
0
Yes, you were correct about the factory sound silencer giving up a little bottom for more top...in 97 this was your only option. Pro Circuit didn't make a shorty silencer for that model, but for the KX80 we do. If you are looking for more bottom end power for your kids bike...go with the shorty silencer. James Stewart used the same silencer when he rode KX80's for Pro Circuit.
 
S

sixds

Member
Mar 25, 2007
779
0
sorry to bring up an old thread


will i actually lose bottom end if i go with the factory sound silencer? will i lose much top if i go with the shorty? how much louder is the shorty?
 
J

john stu

LIFETIME SPONSOR
Jan 7, 2002
790
0
what everybody is trying to tell you is if you use any silencer except a pro circuit you bike will run like one of these :ride:
 
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