Catalytic converter?

[Æon]

I read in the Tiger forum that a guy had removed his cat and the bike ran WAY better afterwards. Does the Street3 have a cat in North America?

[t3ckfr3ak]

Yes, its just before the o2 sensor

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[hatfielddj]

I've been reading on this and had it on my mind for a while. I know it violates US emission standards to remove the cat unless it is registered as a track only bike...All that aside though, does anyone know if it really would increase performance? I'm getting ready to put her up for the winter and do some upgrades while she's resting:

New exhaust, haven't decided on which yet
Modifying the air intake
new air filter
iridium plugs
Michelin PR3 tires front and back

and possibly removing the cat and replacing it with a equivalent SS pipe with a tapped hole for the O2 sensor.

Thoughts?

-Dan

[Wayne's Striple]

The ECU needs the O2 sensor for proper fuel mixture; only race-track professional tuners should mess with that IMO. On my STR I have drilled a lot of extra holes in the plastic air intake, installed a K&N air filter, iridium plugs (same power as the originals but keeps gap integrity longer), titanium DanMoto GP exhaust with baffles ($300, weighs less than 5 lbs and LOUD - use tight fitting ear plugs), and Triumph tune 20589 for aftermarket exhaust. Bike runs flawlessly from idle to redline. Leave the cat in cos it is not worth the hassle just for a hp or two. Also installed a Vortex 520 conversion with 49T rear sprocket; shortens the wheelbase by almost a half inch (axle in middle of slot). A Shorai 18Ah lithium battery cranks like crazy and saves 5 lbs. Btw blow the bucks for the Triumph Quickshifter; you won't regret it! Oh yeah go to the TuneEcu site and order the OBD2 cable with correct ftd chip ($17 using Paypal), and download the program and files and study up while you are waiting for the cable, and you can install the tune yourself. - Wayne

[SkyAdam]

I thought the arrow 3-1 removed the cat. Am I wrong? I know there's still an o2 sensor where the stock should be...

[bira]

Originally Posted by SkyAdam

I thought the arrow 3-1 removed the cat. Am I wrong? I know there's still an o2 sensor where the stock should be...

If I remember right, the O2 is before the cat so yes, I believe the CAT can be removed while retaining the O2 sensor.

[Orangeman]

Originally Posted by Wayne's Striple

The ECU needs the O2 sensor for proper fuel mixture

I am sorry but that is not actually correct. The narrow band O2 sensor and the way it is used by the ST3's ECU is to maintain emissions standard tuning, not proper engine tuning if by proper we are talking about the most power and best running engine. Tuned correctly the bike runs better without it. For the regular street rider there really is no advantage to removing it except for much smoother throttle response due to elimination of the lean off throttle condition caused by the O2 sensor.

EDIT: As a side note you can only remove it if you have also removed the CAT and turned it off in the ECU programming. Do not turn it off and leave it installed, it will quickly ruin the costly sensor.
.

[Nimbus]

Originally Posted by SkyAdam

I thought the arrow 3-1 removed the cat. Am I wrong? I know there's still an o2 sensor where the stock should be...

Yes the Arrow 3-1 lowboy exhaust removes the cat. It is labled as an "offroad/race" exhaust only.

[David L.]

I have remove my CAT on my 2011 speed triple, and don't see ANY difference. And believe me, it's a pain to remove

[bira]

Originally Posted by Orangeman

I am sorry but that is not actually correct. The narrow band O2 sensor and the way it is used by the ST3's ECU is to maintain emissions standard tuning, not proper engine tuning if by proper we are talking about the most power and best running engine. Tuned correctly the bike runs better without it. For the regular street rider there really is no advantage to removing it except for much smoother throttle response due to elimination of the lean off throttle condition caused by the O2 sensor.

You're right orange, the point of the O2 sensors is to maintain close to stoichiometric fuel/air ratio, at low loads anyway, in order to get the cleanest, or most complete, combustion and most out of the catalytic converter for emissions reasons. The stoichiometric point would/should be the optimal air/fuel ratio for performance as well but it's too hot burning and at high loads can cause detonation and damage to the engine which is why the fuel maps are rich at high loads and fuel system is not in closed loop mode at high loads.