Exhaust modification consequences

[Misterprofessionality]

So, I've read one or two things on this forum this way and that, But i thought i'd bring it up for discussion to see if I could get a consensus:

Since there's no Power Commander or other piggybacks available for our bike just yet, Is it foolish to fit a full exhaust with no Cat? I've seen some videos of folks doing nothing but removing the Baffle from the stock exhaust and actually dropping a mile or two off their top speed.

Basically, I'm asking if it would do more harm than good to our bikes to fit an exhaust with no Cat?

 

[m in sc]

computer will still aim for same afr, just takes time to adjust. its fine. Mine didn't lose any speed removing the cat and making a bigger headpipe on the 125 prior to doing anything else. Anecdotally, on 2 other bikes with NO fueling mods, a triumph sprint GT1050 and my 14 cb1100, I decatted the triumph and swapped the entire exhaust on the cb, never remapped. its fine. Better performance on all 3 as a result.

remember: back pressure as a positive is a myth. Period. however, scavenging is required for power and efficiency. for example, cars are a good example: long tube headers will -always- make better power vs short tubes due to the ability to scavenge. And, you will -always- get better scavenging with the cat removed.
.02

 

[Misterprofessionality]

That's good information. I was just worried about making an irrersponsible purchase without knowing what I was up against. Frankly, I'm not gonna change an exhaust to try and get more speed or power on this little bike. I'm happy to do so on my bigger CB1100 (and I have), but i wouldn't spend all that money just to get a half a horse. Mostly i'm looking at systems with a delightful noise and a more practical shape than the stock exhaust. Some have cats (takegawa) and some don't (yoshi) and you can really tell the difference.

 

[m in sc]

I heard a yoshi pipe on a trail last week. Jack, owner of 006 is local to me, we had them both at our local bike night. it sounded pretty darn good. wasn't as obnoxious as i expected, at all. Me? im keeping mine in whisper mode.

 

[Misterprofessionality]

nice....did he have the GP machine song or the black cyclone pipe? yoshi makes two different ones for the CT.

 

[m in sc]

had a silver muffler cover if i remember correctly, by the time we got out there it was dark, was not the all black unit.

 

[Misterprofessionality]

yep, that's the Machine Song. I've seen videos of that it really does sound phenominal. I'm not so jazzed about buying it though because it seems a little impractical....too easy to damage on trail.

 

[dmonkey]

yep, that's the Machine Song. I've seen videos of that it really does sound phenominal. I'm not so jazzed about buying it though because it seems a little impractical....too easy to damage on trail.

I have the same concern, I like the Outex exhaust and know there are fall protectors for it, but even then if it doesn't fall on a perfect surface or brushes against something you'll end up with cosmetic damage. I have the Japanese version of the heat shield over my Takegawa exhaust and both are marked up already. We had "hurricane force winds" (74 mph+) out here that pushed it over parked on gravel. Don't even get a good crash story to tell, just the dang wind.

 

[Misterprofessionality]

yea...that's my fear for sure. my aim is probably going to be to get the Takegawa classic scrambler exhaust. That's a safe choice, and it's very small and low profile. it also fits under the Exhaust crash bar you can buy on Beez. even better, it's low-profile enough that you could hang a side box ammo can off the right-hand side and protect it using your steel storage box.

 

[m in sc]

.. if you mount a metal side case (ammo box) wouldn't that protect the pipe as well? as long as it just sticks out past it.

 

[Dover_MA]

computer will still aim for same afr, just takes time to adjust. its fine.

This is true in closed loop, is it also true in open loop (i.e. heavy acceleration)? I'd read open loop uses look-up tables and ignores O2 sensor feedback.

 

[m in sc]

it interpolates it from closed loop. it's not a static table in open loop per-say. if it were I would have holed a piston a long time ago.

 

[Finding Neutral]

I installed a Yoshimura GP Magnum exhaust only. No power loss. Love the looks and sound. Utilized my exhaust guard as well for drops.
I did the same on my Monkey - Yoshimura RS3, CB500X - Leo Vince, and former Yamaha XT250 - Delkevic. Prior to purchasing all of these exhaust I contacted the manufacturer directly and inquired if they recommended a remap or air intake modification along with these exhausts. All said negative. Only odd issue I've noticed is you will smell a bit more exhaust fumes due to the cat being gone. I was always hesitant to swap out the oem as well, but after doing so was always happy I did. Just sharing. I also have a couple videos on You Tube about my Trail125 exhaust.

 

[Misterprofessionality]

Ah thanks. That's good info. I personally didn't want the yoshi GP because I just had this feeling like it would be too easy to damage off road. I decoded on the Outex exhaust because it comes with really robust heat shields that can be fixed or changed out if they're damaged. It's also a really reasonable price and a decent sound.

My wife on the other hand is getting the Yoshi GP for her super cub. I'm excited about that.

 

[Finding Neutral]

Good call. Especially if your going to be carrying cargo bags and gear. I think the Yoshi's lack of big heat guards would cause problems melting stuff. Happy wife happy life re: Yoshi

 

[B18CXr]

nice....did he have the GP machine song or the black cyclone pipe?

I have the Cyclone and love it thus far. Oil temps are a tad lower and it picked up a solid 3-4mph on the top end, plus it revs out a bit higher so getting around traffic with the 4 speed is slightly easier.

 

[Finding Neutral]

I enjoy my GP as well. Love the looks and note. I'm still waiting on my ecu to do it's thing and am hopeful to see those 3-4mph. Do you know about how many miles you had to put on it before your's kicked in?

 

[m in sc]

nice....did he have the GP machine song or the black cyclone pipe?

I have the Cyclone and love it thus far. Oil temps are a tad lower and it picked up a solid 3-4mph on the top end, plus it revs out a bit higher so getting around traffic with the 4 speed is slightly easier.

Jack.. I was talking about your bike. It was dark, so i couldn't quite see it very well. lol. -Mark