Can a cat become restrictive, you decide
Outstanding HDF Member
Joined: Mar 2009
Posts: 2,216
Likes: 102
From: Central Illinois
If you want to remove the cat, that's awesome but personally I would replace the entire headpipe and hang onto the original headpipe with the cat intact. It is very, very likely that nationwide emissions testing of vehicles, ALL vehicles that use public highways, will become a reality. If the present President gets re-elected, expect it very soon. Without the cat, you will not pass, most likely be fined and not be able to use the vehicle on a public highway. May be worth it to keep that intact cat in case it has to go back on.
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
Likes: 884
From: 'Noke, VA
If you want to remove the cat, that's awesome but personally I would replace the entire headpipe and hang onto the original headpipe with the cat intact. It is very, very likely that nationwide emissions testing of vehicles, ALL vehicles that use public highways, will become a reality. If the present President gets re-elected, expect it very soon. Without the cat, you will not pass, most likely be fined and not be able to use the vehicle on a public highway. May be worth it to keep that intact cat in case it has to go back on.
But at this point in time, is there anywhere in the country that emissions tests bikes?
Thread Starter
|
Road Warrior
Joined: Mar 2008
Posts: 1,783
Likes: 10
From: Oh
Based on that Toyota article it does seem if you run a overly rich afr that damage can occur to the cat. But by whose definition is overly rich? Xieds? Is that overly rich? By using a Super Tuner or a PCV or TTS with either a map from Fuelmoto or a canned map is that overly rich?
Seems to be a lot of variables involved and overly rich would need to be defined
Seems to be a lot of variables involved and overly rich would need to be defined
With that said, most cats are setup with 02 sensors that recognize the standard (14.7 AFR). When we change any of the variables, (i.e.: AFR, AC or mufflers) the O2 sensors will try to lean the AFR as stated in the article. So my point is, by making the change to enrichen the AFR by use of another piggyback ECM or download in order to accomodate a high flow AC, we in fact create a problem with the talk interface between the O2 sensors and the ECM. We are trying to richen and the bike is trying to lean it self out.
IMO this will cause premature failure of the O2 sensors and or the ECM. Only time will tell if this is correct as they haven't been out that long on our bikes. Also IF your cat goes bad, quess what? You have to buy a whole new headpipe, not like a car where you just replace the cat.
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
Likes: 884
From: 'Noke, VA
Just to clear the record, the EPA does't mandate any particular AFR. The EPA does't care what AFR you run, as long as the bike meets emissions standards.
I'd also question why you'd want to run as rich as 13.3:1 across the board. I'm running much richer at high MAP and RPM, but much leaner at low-load cruise. I don't see a need at all to dump that much fuel into the motor and crush my gas mileage.
I'd also question why you'd want to run as rich as 13.3:1 across the board. I'm running much richer at high MAP and RPM, but much leaner at low-load cruise. I don't see a need at all to dump that much fuel into the motor and crush my gas mileage.
Seasoned HDF Member
Joined: Aug 2010
Posts: 5,173
Likes: 177
From: East Coast
A Cat will always be intrinsically restrictive. It is an obstruction in an otherwise empty tube. Try mounting a cat in a brass instrument and try to play it! I'd like to hear a trumpet solo myself.
I'd also be interested (though it does not precisely apply) in seeing how much liquid could be pumped though pipes with and without cats, both by gravity and under pressure.
If it made no difference, why don't racing bikes have them? Excess weight, eh?
I'd also be interested (though it does not precisely apply) in seeing how much liquid could be pumped though pipes with and without cats, both by gravity and under pressure.
If it made no difference, why don't racing bikes have them? Excess weight, eh?
Thread Starter
|
Road Warrior
Joined: Mar 2008
Posts: 1,783
Likes: 10
From: Oh
Just to clear the record, the EPA does't mandate any particular AFR. The EPA does't care what AFR you run, as long as the bike meets emissions standards.
I'd also question why you'd want to run as rich as 13.3:1 across the board. I'm running much richer at high MAP and RPM, but much leaner at low-load cruise. I don't see a need at all to dump that much fuel into the motor and crush my gas mileage.
I'd also question why you'd want to run as rich as 13.3:1 across the board. I'm running much richer at high MAP and RPM, but much leaner at low-load cruise. I don't see a need at all to dump that much fuel into the motor and crush my gas mileage.
Outstanding HDF Member
Joined: Jan 2010
Posts: 2,916
Likes: 31
From: earth
I just had a long interesting conversation with one of the techs at Random Technologies, the guys who build high flow cats for performance automotive applications. My take away was there are too many variables to say what a given effect will be. There is no rule of thumb to say what degree of enrichment will be tolerated by the cat, 14.2, 13.8, 13.4 or whatever, the efficiency of the engine, the cam, and the resultant effects on the catalyst need to be measured to determine what will work for a specific application. I realize that guy who makes and sells the XIEDs said testing was done and reported that the 13.8 was good to go. but I'm a little apprehensive about testing results published by the same folks selling the product, it would be interesting to see the entire test, conditions, variables, and results so you can make your own decision about what is acceptable. Interesting note, that in normal operation running a factory near stoich tune, the temp of the catalyst will be around 1200F, when you start dumping unburnt fuel, as in enrichment or decel effects, the catalyst temps can get over 2000F. So, if you are running an enriched tune for the purpose of heat reduction, and you are still running the catalyst, you are probably actually creating more heat in the catalyst. How much enrichment actually causes undesirable effects is hard to say, for a given application. I'm an a advocate of the near stoich tune for my streetable machines, the power gained from enrichment can only be noticed on a dyno sheet, you'll never feel it on a relatively small displacement 2 cylinder engine like ours. Yeah, running rich technically makes more power but it's not enough to make a noticeable difference with small displacement engines, and most of us aren’t trying to squeeze out an extra 10th of a second on the street for the big win and payout. But running rich is cooler; down to 13.8 the only thing cooler is the exhaust gas temps, CHTs are the same, if you want to run cooler, change cams and keep the lean, clean, crisp, efficient, factory EPA type tune, or put one of those nut shields on. No matter what you do, you are still straddling the rear cylinder and its exhaust headpipe; I don't know why this bike is so hot.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Outstanding HDF Member
Joined: Jan 2010
Posts: 2,916
Likes: 31
From: earth
You can see in my signature what I have done. The bike was tuned at the dealer with the SEPST and I get a consistant average of 43-48 mpg depending how fast and where I am riding. Not that this makes a difference but, this bike runs very smooth throughout the power range, much less heat than stock and I am very happy with the tune. My only purpose in this thread is to discuss the changing of the AFR to accomodate changes from mods while still running a cat and how that will affect flow through the cat down the road.