It's a big forum, I definately wasn't specifically engaging you Ron, I'm glad you are happy with your decision.

 

No one knows for sure? Who are you kidding. I have seen this crosstalk in action. So have a LOT of other folks.

Fine... you don't know me. That's OK... but how about calling Doc in Florida, Jamie at fuelmoto or Steve at Fullsac and ask THEM. PM Lonewolf176 and ask HIM!

WTF, who gives a crap if someone used to tune carbs... this is NOT carbs... this is PID fuel control that is running in the MS range. For the English gentleman... removing the cat will allow pulses or fresh air to engage the WRONG O2 at the wrong time. This is a wobble fire engine, not a Vee nor a straight. All exhausts have multiple pulse waves. Between these pulses, with a common collector like on a stock bike or even a D&D 2-1.... the exhaust always inhales as well as exhales. When cylinder 1 is inhaling and cylinder 2 is ready to fire, cylinder 2's O2 is active and gets the 'breath of fresh air' that is does NOT need. The 135* of crank rotation without a firing event allows the free air 'room' to climb back up the pipe. A V8, etc with even fire... the successive pulses force the free air back out before it can be seen by O2s.

Same old same old. on 07s and 08... the y-pipe played havoc with closed loop, too. Some here MAY remember this... the Y allowed fresh air in to contaminate the O2s. This is the WHY they made the 09 pipe... fixed those issue (Best pipe for a stockish bike is an 09 pipe BTW).

It sounds like a way to 'richen' the bike right? Not so, the extra oxygen isn't always present for both cylinders at any given moment, so when the ECM commands more fuel... it expects more fuel to be seen, and when it commands less fuel it wants to see less... It IS PID control after all. When the ECM doesn't see what is expected... not the best running engine. Can you... English Dude... see this? You KNOW how PID works and it is the 'expected' results that make everything happy, right? It would be like a draft of air inside a unit using PID temp controls... what would happen if that draft wafted by the temp sensors... what would the controller do? Same thing here...

Folks HERE do not understand what fuel control really is... the bike does NOT go down the road all happy at the same throttle setting ... you guys think it is spraying the exact same fuel load when the throttle isn't moved. NOT so. PID involves feedback, and what the ECM does is spray minutely MORE and then minutely LESS fuel with each and every squirt of the injector... the O2s are supposed to 'see' this slight variation and it self adjusts in THIS way. Cross talking and manipulators inside of the circuitry are NOT helpful to this PID action.

One HAS to have each pipe semi separate from each other. The Fuelmoto pipes and the Fullsac pipes accomplish this.

If others want to believe in snake oil, so be it. They THINK it runs better. And... the MOCO, Dynojet, Steve Cole, Doc, Steve, Jamie, etc are ALL dumber and stupid as compared to the king of kings... they Yahoos at XIEDville.

Train... NOBODY, except hopefully English Dude even knows what PID stands for without googling it and TRULY doesn't understand fuel control like FBRR does, right?

Just give it up... HDF is THE untechnical forum, remember? You can lead a horse to water, but old retired dudes, dentists, etc can NOT be made to drink.... just buy more chrome.

Nobody here has even SEEN a dyno. They do NOT even use their Butt Dynos... The STandard in this thread is the Wallet Dyno... I spent money so it must be good... HAHAHA!!!!

 

I'd really like to get rid of the cat in my bike (09 ultra). Anyone in the Sacramento/Folsom/Roseville CA area that's removing them??

 

Wurk_truk, your explanation does make perfect sense to me - thank you.

I would be interested to hear your opinion in the opening question, namely whether removal of the cat improves performance (putting aside other changes that are often made at the same time).

It seems to be universally accepted that there is a temp reduction, but as that is not an issue for me I don't need it for that

 

or use this heat to keep a tea kettle warm

Kidding aside, I have both cat and active exhaust valve. Heat from the engine becomes annoying only after 20 minutes of stop and go traffic during our summer conditions (85°F). My wife feels the warmth of the exhaust pipes on her right leg as we ride but she doesn't complain or say it's excessive.

I will keep the original exhaust as long as I will keep the original cams. I always bought the better parts for preventive maintenance, but I think money is best used when we buy a 'tailored suit' understand a full modification of the engine and it's accessories done by people who have expertise.


BTW, the bottom picture of my post was taken just across the Channel, a few miles South of Great Britain and we didn't suffer from the cat

 

I once had a Pontiac that came with a 305ci V8 engine and had to remove the cat that was falling off the vehicle. After removal, the impression of having additional power was purely subjective and I was told I could have 15 extra HP.

On my 96ci I should perhaps get 5HP if I change the header pipes ???
Is it really worth the risk to de-tune the engine?

You may profit more from learning better trajectories. I come from a flat country where the 1/4 mile race was the reference and had the chance to ride behind Swiss Police officers through the Alps. In the first case you laugh or cry, in the second you swet or suffer as you learn from Pro's. Believe me, the additional 5HP are not very important when you understand how to use what you already have.
Cheers

 

In an effort to try and summarise what we have in these posts, this is what I believe is a reasonable conclusion, if we limit these conclusions purely to:

Gutting the Cat
Putting the head pipe back on and making NO other changes

1. It does appear to be universally accepted that there is a reduction in engine temperature. No one has posted specific data on this in this thread, but it does seem to make a significant difference in high ambient temperatures combined with stop start driving conditions.

2. There are some dyno charts we have seen. Performace increases in the order of 5Hp are indicated by these charts, but there are some questions as to whether the before and after tests were solely limited to "gutted cats". For every person that argues "significant" improvement in performance there is another that says "no" improvement, so it is probably best that we follow the dyno charts and hope that one day someone will post a chart which specifically limits the test to this.

3. There is enough smoke out there reference the cross talking issue to believe that there is a probability of fire. Based on the subsequent explanations offered by Wurk_Truk, Fabrik8r and Joflewbyu2 personally I am satisifed that this is a legitimate concern - but then each person needs to make up their own mind on this. What I would be interested to hear next is how one can recognise this cross talk issue whilst riding? I am guessing it would be a missfire or timing but I am no expert in that.

The other issues discussed were all interesting in their own right but really smoke and mirrors in terms of understanding this issue.

Me personal conclusion - I won't be gutting.

 

Gutting the CAT does not reduce engine temps, it eliminates the extra heat caused by the CAT. The CAT is what causes the extra heat.

Good luck for all riders. I don't believe in de-CATed headers, I'd rather buy an engineered header. That's just me. Enjoy what you have and go out and ride.

 

Understood and good point

 

for you tuning savvy guys, what happens if you gut the cat(to eliminate excess heat on rider and passengers leg-not motor heat) and have the dealer do a stage 2(normally used when changing cams) download...leaving mufflers and air cleaner stock?