Exhaust baffle removed on a CRF 230

[mixxer]

Gotta throw in some Dyno driven info on what makes the power go where....

Restricting outlet area has, as counterintuitive as it may sound, the biggest initial effect on midrange power and peak torque...

Since the torque peak is actually the max effective point of cylinder fill.... Power increases above that point by rpm and inertia, not by more efficient cylinder fill... The goal is to limit torque loss as rpm rises past torque peak , in order to chase maximum peak horsepower ... 

Many engines will still make close to peak power as you restrict outlet area... To a point of course... Lots of quiet cores make the same peak power...

It's the midrange that gets the knees kicked out from under it... Weak midrange and lower torque and throttle response ...

I have tested many many exhausts that use the supertrapp disc diffusers on 450s.... By the time you make the most possible torque you will have 18 discs in there.... Makes straight pipe Harley's sound reasonable....like sticking your head in a jet engine... By the time you have enough discs to reach peak torque, you might as well save some weight and toss them in the trash and run open exhaust as far as sound control is concerned...

By the time you reach a modicum of sound control by removing discs... You have killed between 10-20% of your midrange power... But peak is unaffected.... Midrange and beefy broad shouldered torque curves are always my goals... Screaming for peak power and rowing a bike around with clutch feathering and shifting like a one legged square dance caller bores the BEEJEESUS out of me...

Have always hated supertrapp exhaust setups... Emperor's New Clothes sort of deal for me...

Maybe they are ok on the 230... Have not tested on a 230... But they do suck on all I have seen... 

And they are fugly too... Which I could overlook if they worked...

One grizzled curmudgeon's test driven opinion... Ignore at will...lol

[VortecCPI]

29 minutes ago, mixxer said:

Have always hated supertrapp exhaust setups... Emperor's New Clothes sort of deal for me...

Maybe they are ok on the 230... Have not tested on a 230... But they do suck on all I have seen... 

And they are fugly too... Which I could overlook if they worked...

One grizzled curmudgeon's test driven opinion... Ignore at will...lol

Agreed.  Always a Love-Hate relationship when it comes to SuperTrapp...  Or SuperCrapp as BTR calls them.

I happen to like them and after speaking with Frank at Engines Only and Ben at Ben's V-Twins here in Charlotte I have heard lots of good feedback when used on mild singles.  No feedback at all on high-strung high-tech 450s as I do not play in that arena (and never will).  I am pretty sure I saw SuperTrapp disks on some of Terry Miller's custom exhaust systems as well.

I have had zero complaint from other riders with respect to the exhaust noise from either my CRF230 or SRX600.  However, these two engines are mild docile beaters compared to any stock high-tech 450 so that is apples and oranges.

Years ago Frank was going to try to put a CRF230 back on the dyno comparing stock non-baffled exhaust with PoweRing.  I would like to see that.

[mx4god]

Thanks, I will remove some discs after getting the bike to run properly.

[adnohguy]

Agreed.  Always a Love-Hate relationship when it comes to SuperTrapp...  Or SuperCrapp as BTR calls them.
I happen to like them and after speaking with Frank at Engines Only and Ben at Ben's V-Twins here in Charlotte I have heard lots of good feedback when used on mild singles.  No feedback at all on high-strung high-tech 450s as I do not play in that arena (and never will).  I am pretty sure I saw SuperTrapp disks on some of Terry Miller's custom exhaust systems as well.
I have had zero complaint from other riders with respect to the exhaust noise from either my CRF230 or SRX600.  However, these two engines are mild docile beaters compared to any stock high-tech 450 so that is apples and oranges.
Years ago Frank was going to try to put a CRF230 back on the dyno comparing stock non-baffled exhaust with PoweRing.  I would like to see that.

I have posted on the subject before but will re-cap:
IMO: according to my own experience and Butt Dyno:

Last October, 6 weekends in a row, including a whole week between 5 - 6: I tried every option that was available to me for a quiet exhaust system that made more power than what I have been using for approximately the previous 5 years.
This was at 4-7500 K elevation with 35-80 d outside air temps.

After ordering, with many weeks of waiting, I was very excited and installed my EO reverse cone megaphone exhaust system on my 262cc 230f...

BUT: Super loud and very irritating with 12 disks.

I ran a EO Power ring with twelve disks for several months on a stock muffler and oversized (powroll) header before. With the power ring installed, it was acceptably quite with a noticeable power increase, AFTER I went down 4 sizes on the main jet.
Again: Noticeable increase in power and still reasonably quiet. Happy with a power ring installed.

Back to the "new" reverse cone megaphone system:

Removed 2 disks from EO system, (12) while SLIGHTLY more quiet, still the noise was totally unacceptable and now I lost some of the famous 230f low rpm torque. Now my 262 had a "powerband" that resembled a 2 stroke coming "on the pipe" as the engine rpm raised above 5-6 K rpm.

Went down to 10 disks. More quiet but still too much noise!
Then 8 disks:
Bike loaded up, ran way to rich, NO LOW RPM POWER.
Very pronounced power band above approx 6k rpm. Dead power below that, had to lower gear ratio, had to use lots of clutch slipping out of turns.... Hated it! (It SEEMED FASTER WHEN IT was above 6k rpm) but looking back it was just way slower below 6 K rpm.

Could have rejetted for this condition, but it lost so much power and was simply too friken loud any way.

Swapped muffler with a "CHM" , kept oversized EO header pipe, (larger than my Powroll header) installed EO power ring with 14 disk on the end of my CHM muffler.

Wow [emoji15] very quiet! More quiet than the stock muffler with the same power ring and 12 disks.

ALL of my lost 230f, off idle torque returned, plus much more power all the way to approx 8K rpm.

Returned to my original (higher) gearing.
No more clutch slipping needed out of tight turns.
Noticeable increase in power, huge smiles were back again.

After a frustrating 5 weeks of trying many systems and combinations, I achieved my goal, Had much less noise with more additional power.

I did find a home for the reverse cone muffler system on my 247cc 5spd kick start 150f
10 disks now, still a touch loud but what an improvement in overall power... a big difference.

But this engine was completely built by Frank at EO and the only changes that I have made is much more compression, super light flywheel and crank shaft is also lightened. ( other than several complete refreshing's including I'm on my third set of cases... (big kick start gears don't break any more but the cases pop open Ike a pumpkin at times)

It has the CHM stainless header on it (same ID as powroll) but much smaller ID than the EO header on my 230.

[mixxer]

Awesome write up Guy...

Thank you for taking the time to share your insight/experience..

[mx4god]

Thanks for sharing, Guy. With that said, I'm still baffled at how loud mine is with my power ring on the stock muffler and powerbomb head pipe. It has 13 discs, although the last one looks almost completely covered by the end cap.
My dad was inside the house when I took it for the initial ride after rebuild and said it was pretty loud and had a bark to it. I have a sound meter that I haven't used yet, but I'd guess it's mid 90s for decibel rating, and that's just way too loud for certain riding areas I ride at. If stock is 82db, then I'd like 85- 88db.

[VortecCPI]

7 minutes ago, mixxer said:

Awesome write up Guy...

Thank you for taking the time to share your insight/experience..

Agreed.  Thank you Guy!

I suppose in my case my engine is so mild it just doesn't move enough air or have enough CR to make much noise with Frank's system.

I have not run anything but the 10 disks Frank supplied it with.  However I do have a SuperTrapp story on the SRX600...

My father used to run the bike with only a few disks (6-8) because he didn't like too much noise.  He added a few more just before I brought it home and it ran fine when I rode it with 10-12 disks.  I increased to 16 disks and then I experienced lazy/sloppy throttle feel and response.  The bike was having issues with uphills and wind and required more throttle input than it did with fewer disks.  I checked the float level and it was quite low so I fixed that and all was fine.  Super crisp and sensitive throttle feel and response and no more issues with uphills and wind.  Now I run 10 disks and an open end cap based upon advice from Frank Nye and it runs great idle to top.

So...  In my case with the SRX600 less disks needs leaner mixture and more disks needs richer mixture.

[adnohguy]

Thanks for sharing, Guy. With that said, I'm still baffled at how loud mine is with my power ring on the stock muffler and powerbomb head pipe. It has 13 discs, although the last one looks almost completely covered by the end cap.
My dad was inside the house when I took it for the initial ride after rebuild and said it was pretty loud and had a bark to it. I have a sound meter that I haven't used yet, but I'd guess it's mid 90s for decibel rating, and that's just way too loud for certain riding areas I ride at. If stock is 82db, then I'd like 85- 88db.

My 262 "WOULD" have 13-1 compression ratio with a stock stroke crank but I have a 4mm stroker on top of that. (So maybe 13.5-1 or somewhat more than 13-1)
It's got a lot of compression "Pop" . This is very hard to quiet to an acceptable level.
My 247cc only has 12.5-1 so it's not as loud as my 230f anyway.

I don't remember what your running but more compression than stock = more exhaust noise on a 230.

How large your engine is, how well it's ported, how much cam, what kind of RPM your running at, how much larger the carb, would determine how many disks to use.
Added Compression, while it makes more noise out the exhaust, does not effect how many disks to use as much (for power) as all of the above.

I'm surprised your stock muffler is too noisy with the power ring?
If your at stock cc still, 8 disks should be fine for power and less noise.

[mx4god]

Stock CC with wiseco piston, thin head gasket, 2.0 cam, stock carb. Thanks for the info. I realize more compression is going to be louder, but based on what info others have given on this setup, it's under 11:1.

[adnohguy]

Stock CC with wiseco piston, thin head gasket, 2.0 cam, stock carb. Thanks for the info. I realize more compression is going to be louder, but based on what info others have given on this setup, it's under 11:1.

Your bike should run well (compared to stock)

[adnohguy]

Stock CC with wiseco piston, thin head gasket, 2.0 cam, stock carb. Thanks for the info. I realize more compression is going to be louder, but based on what info others have given on this setup, it's under 11:1.

 

 

 

I ran this setup for 5 years on two bikes.

It's cheap and I encourage you to try it. See what you think.

 

Very pleasing deeper tone. Not too loud (IMO)

But since then, these have been replaced with power rings (because, IMO, they make more power)

 

If you want to sell your power ring in the future, pm me.

 

 

[mx4god]

2 hours ago, adnohguy said:

 

 

 

I ran this setup for 5 years on two bikes.

It's cheap and I encourage you to try it. See what you think.

 

Very pleasing deeper tone. Not too loud (IMO)

But since then, these have been replaced with power rings (because, IMO, they make more power)

 

If you want to sell your power ring in the future, pm me.

 

 

Is it just an angled pipe that is riveted/screw to the stock end cap? Is the stock baffle removed?

I made my own power ring. Not sure what the original looks like, but I made two different rings. The first one, which is currently on the bike, I made to the full size of the muffler outlet without the end cap. The second one is a much smaller outlet in hopes that it would quiet it down if needed. I had a spare supertrapp end cap with some discs that I used to bolt on to the ring.

 

[mixxer]

10 hours ago, mx4god said:

Is it just an angled pipe that is riveted/screw to the stock end cap? Is the stock baffle removed?

I made my own power ring. Not sure what the original looks like, but I made two different rings. The first one, which is currently on the bike, I made to the full size of the muffler outlet without the end cap. The second one is a much smaller outlet in hopes that it would quiet it down if needed. I had a spare supertrapp end cap with some discs that I used to bolt on to the ring.

 

If you want it quiet, you have to get rid of the hole in the middle... The supertrapp discs aren't doing anything when there is an open end on the cap..

[VortecCPI]

35 minutes ago, mixxer said:

If you want it quiet, you have to get rid of the hole in the middle... The supertrapp discs aren't doing anything when there is an open end on the cap..

I believe that is a different adapter flange, not an end cap.

Technically an open end cap does not always defeat the disks and the disks are doing something.  This chart was developed using data from SuperTrapp and you can see an open end cap works in conjunction with disks, and that an open end cap is the equivalent of 17 disks.  In the case of our puny 230s none of this matters much but when displacement gets big, like my 600cc, it makes more sense.

All data shown is for 4" disks.

[mx4god]

If you want it quiet, you have to get rid of the hole in the middle... The supertrapp discs aren't doing anything when there is an open end on the cap..

Haha, yes this is just the adapter that the discs bolt to. The end cap is closed.

[Clyde]

DB Dawg 8001. A little bit louder than stock baffle but really opens up exhaust.

[RedMesa]

On 12/13/2015 at 7:25 AM, RedMesa said:

> Bikers Choice Exhaust Pipe Baffle 1-1/2" OD Steel 64301 492611 - $6.50.

I plan to do a before and after "SAE J1287 stationary sound test" to measure how much effect the baffle has: 

Finally did this. Here are the results

https://docs.google.com/document/d/1mEsw891e5HUdLIrq4yYQzm2QCsRgK-ihDkrL_fu7_iA/pub#h.nor3lvjbpjz0

[Chuck.]

A 90 degree down turned outlet can reduce sound 2-3db by redirecting the sound down against a soft surface, negligible when on a hard surface like asphalt or concrete. Two have already been mentioned in this thread. The CRF250X uses an insert with the same OD as the 230 so my example of a X outlet will work on a 230.

I use a piece of 1 1/2" plumbing trap (brass) purchased from Home Depot and cut out a 90 degree section and then expanded one end to 1 1/2" ID so it would fit over the spark arrestor, then secured it with the same bolt that hold in the insert. 

250X muffler on XR showing expanded ID of the outlet to fit the muffler, and the retaining bolt:

Down turn outlet on a CRF250X (dents are from trying to ride gnarly technical trails with a heavy bike)

And the parts:

Edited July 31, 2017 by Chuck.

[Chuck.]

The outlet on the insert in the previous post has a 20mm ID for an area of 314 sq mm.
Removing the insert and the muffler outlet is 37mm for an area of 1075 sq mm, which explains the uncorking with the insert removed.

The four oblong slots are 10x14 for a total area of 560 sq mm.
And I added a 9mm hole on the left end for another 64 sq mm, bring the total for holes to 624 sq mm, almost twice the area of the insert's outlet.
So the restriction is the 20mm ID outlet (314 sq mm) on the insert.

What is needed is an insert with an ID larger than 20mm.

What is the ID of the CRF230F insert?

[Chuck.]

On 7/31/2017 at 8:53 AM, Chuck. said:

A 90 degree down turned outlet can reduce sound 2-3db by redirecting the sound down against a soft surface, negligible when on a hard surface like asphalt or concrete. Two have already been mentioned in this thread. The CRF250X uses an insert with the same OD as the 230 so my example of a X outlet will work on a 230.

I use a piece of 1 1/2" plumbing trap (brass) purchased from Home Depot and cut out a 90 degree section and then expanded one end to 1 1/2" ID so it would fit over the spark arrestor, then secured it with the same bolt that hold in the insert. 

250X muffler on XR showing expanded ID of the outlet to fit the muffler, and the retaining bolt:

Down turn outlet on a CRF250X (dents are from trying to ride gnarly technical trails with a heavy bike)

And the parts:

The outlet on the CRF250X insert has a 20mm ID.  I got an idea from this thread regarding the power ring so I made one that will fit in the insert opening and has a larger ID, it also allows using the down turned outlet.

The second hole is to help hold the down turned outlet