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Decatting

30K views 83 replies 37 participants last post by  iarapilot 
#1 ·
My dealer has had these made for the speed twin and is in the process of producing them for the Thruxton R.
His opinion is that they run fine with the standard tune/map.
Apparently a two hour job to install as the left side frame tube needs to be unbolted to get the cat out.

Anyone else got something similar or done this? Planning to get it installed next week at 1st service.
Skiddy
 
#9 ·
They have one installed on a street twin with V&H cans and I'd rate it as offensively loud. I have a pair of cheap reverse cone mega's on my air cooled Thrux so I know loud and this had me having second thoughts.

I plan to stick with the standard cans. on the R.

They have had them made in the past for the Thunderbird, which apparently took 2 or 3 retries before they got no code failures etc. This one worked first time.

They are having them made by a known local exhaust supplier, his name is on the plate, but have a 12 month exclusive sales arrangement with him.

I let you know how it goes next weekend.

Skiddy
 
#10 ·
Thanks McSkids!!!

I am very interested to 'hear' what you have have to say! I guess I would get this 'mid-pipe', and then get the Vance&Hines 'off-road' cans, just because they look smaller in size... And I would leave the removable baffle in.
 
#18 ·
Oliver Motorcycles
Address: 1098 Ipswich Road, Moorooka QLD 4105, Australia, Brisbane QLD 4105
Phone:(07) 3193 4444

Usual disclaimer that I have no connection with them other than as a customer, no guarantee that they will work etc.

Number of comments about straight through pipes would be better, I agree but the intent is that no modification is made to the existing headers or silencers, this piece is hidden behind the existing covers and retains a balancing function.
It is not a Triumph part and not Triumph approved. It is an after market widget and its in the shop now. That's more than can be said for Triumph or any other aftermarket parts supplier.

YMMV
Skiddy
 
#13 ·
According to what I have read on the Triumph website, it seems that that The E-Marked slip on exhaust cans are street legal, with a non-removable Db killer… And the Off-Road exhaust cans have a Db killer inside of them, but they are also removable.
 
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#16 · (Edited)
I would be very surprised if they used a different cat on the T120 and the Thruxton/R....That de-cat looks good but it would be far better with a straight flow from the front to the back without the bend, But I'm sure it will work pretty well for most people...
I've gotta say I'm not convinced with the no re-tune part, if it it was with the E-marked silencers I'm sure it will be fine, but the off road ones, maybe not so good...

Why is this thread not in "technical talk"?
 
#25 ·
Because this subject has been flogged to death in other threads.
There are many "cat-eliminators" or "X-pipes" to remove the cat, but none are official. Some people report extremely lean running, and some mechanics have reported that the bikes they worked on with the cats removed run terribly, while some owners bought them and say that their bikes run fine.
We've not yet seen a before-after dyno chart from anyone other than a salesman, Triumph say it will void any engine warranty claim if fitted (although they haven't seen any issues yet), so you can feel free to buy and fit one if you like. You can also perform your own ingrown toenail surgery, vasectomy, or any other procedure you like so long as you are prepared to accept the risk yourself, but for any of the above I would either seek the advice of a professional with no vested interest, or review scientific measurements from multiple independent sources. I certainly would not take the opinions (often mistakenly referred to as "advice") of members of the public on an internet forum.

Now, I'm going back to browsing "www.diy-vasectomy.com" and see if the 'two-brick' method mentioned there has any side-effects. My doctors has strongly recommended against it, but several people there say they are very happy with the results!
 
#28 ·
The only thing is that the new bikes require the RFID in the key, so are essentially already RFID enabled.
Sticking the key under your skin is probably not feasible :)

I have some active RFID devices here that take a battery and so are more powerful than the skin-embedable ones, and you could use these on your keychain to do the same thing as you approach your bike. That would be neat, to disarm the alarm and turn on the ignition when you stood next to the bike, but again we can't do this without the ECU based security system transponder being deactivated. I suppose you could epoxy the key transponder to the sensor, but then hot-wiring it would be a awfully easy :)
 
#29 ·
I can't help but chuckling to myself when I read this, and similar, threads. I am not against anyone doing anything they want to their bike. After all, it is there bike. But if you want a muscle bike, for gosh sakes, why not just buy a V-max or whatever it is that tickles your fancy. And if you wanted to remove the Cat converter on a V-max or similar, I could understand this testosterone induced logic. But to take your mildly tuned new Triumph and do an out-of-character mod like this that probably ruins the bike's resale value, creates a potential tuning nightmare, all for a very marginal performance benefit..... it blows my mind. Again, people are going do what they want to their motorcycles, but sometimes I just totally fail to see what motivates them.
 
#32 ·
People also fall into the trap of assuming any modification increases power. Take the plastic mesh off the air-inlet and I'll have ram-air! Drill the baffles out of my OEM exhaust and it'll be free-flowing power boosted!
The reality is that the manufacturer doesn't cripple the power unless it's a learner bike. The bike manufacturer spends millions getting the exhaust and engine combination optimal for the emissions standards. They won't create an engine capable of 120HP then cripple it using the exhaust to meet standards, but will modify the engine to produce 90HP with higher torque, knowing that the bike is intended to produce that power, and no matter what you do to the exhaust you will not get 120HP unless you make significant engine changes too, such as modifying valve and ignition timings.

What we can do is to fiddle with the mixture to produce a less-lean setup that improves the responsiveness of the throttle. At the moment the Thruxton can be a little bit hesitant when you snap it open, probably because it's designed to be extremely thrifty with the fuel, and I'd love to have a PCV like @TriRocket3's so I could try richening it up a bit at those low RPM wider throttle settings. Certainly every carb bike I've owned has benefited hugely from K&N jet kits, even with stock exhaust. Decatting does exactly the opposite, making it an illogical way to "improve" anything other than sound.

Adjusting is tricky on the Thruxtons and T120s because we can't remap, so we can either add a PCV or fool it with a resistor on the sensor, but once we have a way of hacking the maps it will all be a lot easier :)
 
#35 ·
... The reality is that the manufacturer doesn't cripple the power unless it's a learner bike. The bike manufacturer spends millions getting the exhaust and engine combination optimal for the emissions standards. They won't create an engine capable of 120HP then cripple it using the exhaust to meet standards, but will modify the engine to produce 90HP with higher torque, knowing that the bike is intended to produce that power, and no matter what you do to the exhaust you will not get 120HP unless you make significant engine changes too, such as modifying valve and ignition timings....


You are correct, but don't forget that manufacturers are not the only ones that understand engine design and tuning. Moreover, they often are designing to a price point. So it is definitely possible to get more power out of most bikes.
 
#36 ·
Decatting does exactly the opposite, making it an illogical way to "improve" anything other than sound.
Sorry I disagree, decat when properly tuned for the increased flow, will improve efficiency.
But you don't tune a decat. That's like saying that replacing the airbox with free flowing ones will make your bike run rich... as long as you replace the injection system with a richer running one. In your case your bike can run rich or lean depending on your PCV settings. People adding a cat eliminator alone (which most are doing, and is being promoted by some of the suppliers) don't have that as an option, hence why eliminating the cat can only make the system run lean and you will have to find a way to force it richer such as splashing out on a PCV + dyno runs or a resistor bodge.

It will also hopefully be more powerful and less efficient, but I know what you mean :)
 
#37 ·
None of the naysayers have offered a shred of evidence to support their obviously biased opinions.
Let's start with solid facts
How lean is too lean?
What is the optimal AF ratio
What is the AF ratio of a std bike?
A modified bike?
How are today's lean burn engines surviving and producing so much hp?
Where did you get your engineering degree?
When?
How many years experience do you have?
Otherwise your opinion like a belly button; everyone has one
 
#39 ·
I don't think most of us here are naysayers; instead, we just want to see the facts. Personally I'd like to see baseline and modified dyno runs, including A/F ratio data.

BTW, lean-burn engines are designed to run that way. There's a complex interrelationship between combustion chamber shape, intake and exhaust port shape, valve timing, ignition timing, bore size, etc, that allows for lean burn without damage.

BSME, 1983, concentration on internal combustion engine design :smile2:
 
#41 ·
I don't think people are naysayers about the decat, but when people really really want to justify something to themselves they will argue that people have no "evidence" otherwise, like cigarette smokers point out that their Grandfather smoked until he died at 92, so anyone who points out the health risk is talking rubbish.

We have a number of people (I know of four so far) reporting running issues after a decat, and a couple of firms selling unofficial mods telling us they are fine. You decide who is most likely to give an unbiased account of the situation and make your own mind up. You don't need anyone's opinion from these forums, just any facts you can glean from amidst all the noise :)

It's a fine line between pessimism and realism.
 
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