Do I need to remap for stock exhaust with decat link pipe?

[Drstimpy]

Got a Leo Vince link pipe and I’m wonder if I need to remap for just that...
I would prefer not to if it isn’t an issue.


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[Chuditch]

yes I would use a PCV or other piggy back to get the best out of it. Any mod that increases flow will result in leaning out. Probably run, but not in a performance kind of way without altering fuelling and ignition.

Not too fond of remapping.... I run a decat before the 'tea pot' and a stock exhaust with an open air box on my 2017 RC, got to use a PCV or bad things might happen with those mods without one..

 

[Drstimpy]

Any symptoms of “bad things?”


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[mattv]

Performance will suffer and your engine will run hotter. It may stall, not idle well, power could cut in and out, etc. The bike runs lean from the factory; decat will make it worse.

If you just want more noise, use a slip-on, or remove the baffle from the stock exhaust. If you want performance, decat and piggyback ecu.

Removing the baffle from stock: https://www.youtube.com/watch?v=Ck-d6RKa9nc

 

[Drstimpy]

I would prefer stock levels of noise.
Maybe I just need to do the experiment and ride it with a link pipe.
I mostly wanted to save the weight and don’t need any change in performance really

 

[TylerH]

My 2017 did not have the lean symptoms that other people report, no part throttle surging, no running hot (south Florida). with the cat delete pipe installed it did not run any different...the noise level with the stock pipe did increase, and the closed loop fuel mileage dropped a little. It did not seem to run any hotter as it is a street bike and was in closed loop mode. After 3 weeks I installed the Power commander V with the mod map, and the wide band 2. after 2 weeks I have noticed it runs smoother at lower rpms and has better throttle response .( I filled in the tables for the WB2). Thanks to Hard Racing for their help.


2017 RC390
2006 Derbi GPR125R
2005 Raw ZX6RR

 

[mattv]

My 2017 did not have the lean symptoms that other people report, no part throttle surging, no running hot (south Florida). with the cat delete pipe installed it did not run any different...the noise level with the stock pipe did increase, and the closed loop fuel mileage dropped a little. It did not seem to run any hotter as it is a street bike and was in closed loop mode. After 3 weeks I installed the Power commander V with the mod map, and the wide band 2. after 2 weeks I have noticed it runs smoother at lower rpms and has better throttle response .( I filled in the tables for the WB2). Thanks to Hard Racing for their help.


2017 RC390
2006 Derbi GPR125R
2005 Raw ZX6RR

Good info. I should have stated in my previous post, that I was just taking my best guess. I hadn't actually tried any exhaust modifications without a piggyback.

 

[Drstimpy]

OK… Where is the mystery fastener that is holding the catalytic converter after I’ve removed all the obvious ones? I know you know[emoji48][emoji48][emoji48]


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[mattv]

Can't remember any hidden bolts. I do remember it was a pain to get out once all the fasteners were removed.

Maybe the clamp on the header pipe?

Here's a video that shows the removal: https://www.youtube.com/watch?v=_RqHaf1Yyu4

 

[Drstimpy]

Thanks!
There wasn’t a fastener there might as well of been because of the interference fit from the sleeve between the brackets in the catalytic converter. A lot of back-and-forth working it finally got it out.
Man the cat is heavier than my real mammal cat!
I’m going to take it for a ride today and see how it is fueling. Hopefully there won’t be a lot of difference


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[Drstimpy]

Well the big issue is resolved. At least for me.
I installed the Leo Vince link pipe last night and rode it all day today in every possible way. It was 70-80 degrees. I rode it cold and hot. Short shifted and revved it out. Hard cornering and 100+ for 10 min on the freeway. WOT and every manner of part throttle. Slow city riding and country lane cruising.
What did I notice?
Zip, zilch, nada, nothing, zero...except for slightly more pleasant exhaust tone.
No backfires, no surging, no overheating, no change in performance or throttle response.
So, my informal conclusion is...either the stock map is fine or the link pipe doesn’t change the flow characteristics enough to matter in a real world application.
Research done for now.
You’re welcome[emoji482]


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[Formula390]

Butt Dyno is horrible for accuracy.

Stock map is lean. Period.

Any changes to the intake or exhaust without modifications for fueling can cause lean conditions that already exist to get worse. Will your motor blow up right away from opening up the exhaust... nope. Will it shorten your engine life and likely contribute to early failure... yep. There has been PLENTY of research in these departments and disregarding that is done at your own risk.

There is a REASON people were telling you to be cautious and to seriously consider making fueling modifications. {shrug}

 

[Drstimpy]

Formula 360
First of all thank you for attempting to educate me. If my goal were ultimate performance, I would tune it with a dyno and analyzer right now.

I accept that you have much more knowledge than me on this topic. But you have to respect my skepticism about the horrible lean condition. I’ve owned 35 motorcycles and had to correct plenty of lean fueling conditions...both with a carburetor and FI. ALL of those lean conditions created SYMPTOMS. Backfiring, surging, unstable idle, etc etc etc.

I’m not using a butt dyno for Power assessment so that comment isn’t really relevant but people quote it all the time.

I’m just really having trouble understanding how asymptotic lean conditions are going to ruin my life[emoji56] You, yourself state the bike runs lean from the factory and yet parts aren’t blowing all over the roads around the world. Also, aftermarket fueling schemes make a lot of money for a lot of people...including you...no offense...and that fact needs to be expressed in this conversation.

Remember, all I did was install a Leo Vince link pipe. No intake mods and stock exhaust. Also it’s a road bike that gets a few trackdays a year under a fairly slow and conservative old guy.

Right now I’m still waiting for a rational, evidence based argument as to why it is mandatory that I change my perfectly functioning, asymptotic fueling. So far all I have is quotes from the journal of handwaving [emoji48]

Finally, in those years of 35 bikes I have been down the fueling rabbit hole enough to know that better is the enemy of good[emoji85]






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[mattv]

better is the enemy of good

Never heard that one before, I like it.

So, if you hold the throttle steady at around 25 - 35mph in 2nd or 3rd gear, you don't experience any surging? Are you by chance at high altitude?

 

[simpletty]

Formula 360
First of all thank you for attempting to educate me. If my goal were ultimate performance, I would tune it with a dyno and analyzer right now.

I accept that you have much more knowledge than me on this topic. But you have to respect my skepticism about the horrible lean condition. IÂ’ve owned 35 motorcycles and had to correct plenty of lean fueling conditions...both with a carburetor and FI. ALL of those lean conditions created SYMPTOMS. Backfiring, surging, unstable idle, etc etc etc.

IÂ’m not using a butt dyno for Power assessment so that comment isnÂ’t really relevant but people quote it all the time.

IÂ’m just really having trouble understanding how asymptotic lean conditions are going to ruin my life[emoji56] You, yourself state the bike runs lean from the factory and yet parts arenÂ’t blowing all over the roads around the world. Also, aftermarket fueling schemes make a lot of money for a lot of people...including you...no offense...and that fact needs to be expressed in this conversation.

Remember, all I did was install a Leo Vince link pipe. No intake mods and stock exhaust. Also itÂ’s a road bike that gets a few trackdays a year under a fairly slow and conservative old guy.

Right now IÂ’m still waiting for a rational, evidence based argument as to why it is mandatory that I change my perfectly functioning, asymptotic fueling. So far all I have is quotes from the journal of handwaving [emoji48]

Finally, in those years of 35 bikes I have been down the fueling rabbit hole enough to know that better is the enemy of good[emoji85]






So I take it you have the understanding of open and closed loop control?
[FONT=&quot]Closed Loop systems usually operate at low throttle openings (below 20%) and below 50 to 60% of max RPM. Above those throttle and RPM points the system goes back to Open Loop operation, running off the fuel maps stored in the ECU.[/FONT]
[FONT=&quot]The RPM at which the Closed Loop / Open Loop switch happens is generally determined by the maximum speed reached during the test cycle, how hard the vehicle has to work during said test and the chosen gearing for the vehicle. This is why changing final drive ratios (sprocket sizes) is considered breaking the law – it changes the vehicle form how it was homologated.[/FONT]
[FONT=&quot]The throttle position at which the Closed Loop / Open Loop switch happens is generally determined by the relationship between engine size and the size of the throttle bodies, and by how much load (and therefore throttle angle) the test requires the engine to provide. Cruising at 100km/h on a 900 – 1000 Ducati 2V engine with 45mm throttles will see a throttle angle around 10 degrees, whereas on a 4V of the same capacity with 50mm throttles will be around 8 degrees. Not a big difference, but as all the Ducati 2V engines run the same 45mm throttles you can see the difference 620cc will give as compared to 1000cc.[/FONT]
[FONT=&quot]To show this a little more clearly IÂ’ll show a fuel map with approximated switching values, with the Closed Loop section in green and the Open Loop section in blue. This is a 916 std fuel map, but itÂ’ll do just fine for now. As you can see, the idle is also controlled by the Closed Loop system. The logic is simple - RPM and throttle inside green zone: Closed Loop, RPM and throttle outside green zone: Open Loop.[/FONT]

FUEL MAP (milliSeconds)

THROTTLE degrees​

7.1​

7.1​

8​

8.8​

9.1​

9.2​

9.4​

9.4​

9.6​

10.2​

10.6​

11.8​

11.8​

11.7​

10.9​

10.7​

79​

7​

7.1​

7.5​

8.1​

8.8​

9.1​

9.3​

9.3​

9.5​

9.8​

10​

10.6​

10.6​

10.6​

10​

9.5​

57​

7​

7​

7​

7.9​

8.7​

9.1​

9.1​

9​

9​

9​

9.2​

8.9​

8.4​

8.1​

7.8​

7.6​

42​

6.4​

6.4​

6.8​

7.5​

8.3​

8.9​

8.5​

8.3​

7.9​

7.5​

7.3​

7.3​

6.8​

6.5​

6.3​

6.1​

33​

6.3​

6.4​

6.4​

7.2​

8​

8.8​

8.4​

8.1​

7.6​

7​

7​

6.6​

6.4​

6.1​

6​

5.9​

29​

6.1​

6.1​

6.2​

6.8​

7.8​

8.6​

8.2​

7.9​

7.3​

6.6​

6.7​

6.4​

6.1​

6​

5.8​

5.7​

26​

5.7​

5.6​

5.6​

6.2​

7​

7.5​

7.4​

7​

6.4​

5.9​

5.9​

5.5​

5.3​

5.3​

5.1​

5​

21​

5.2​

5.1​

5.2​

5.7​

6.3​

6.6​

6.2​

6.1​

5.5​

5.2​

5.2​

4.8​

4.6​

4.2​

3.9​

3.5​

17​

4.6​

4.7​

4.7​

5.2​

5​

5.3​

5.2​

4.9​

4.6​

4.3​

4.3​

4.3​

4​

3.4​

3​

2.8​

12​

4.4​

4.4​

4.4​

4.3​

4.3​

4.4​

4.3​

4.1​

3.9​

3.6​

3.4​

3.3​

3​

2.8​

2.4​

2.3​

9​

4.3​

4.2​

4.1​

3.9​

3.7​

3.6​

3.6​

3.2​

3​

2.7​

2.5​

2.4​

2.3​

2.3​

2.2​

2.1​

6​

3.9​

3.9​

3.6​

3.3​

3.2​

2.7​

2.7​

2.4​

2.1​

2.1​

2​

1.9​

1.9​

1.8​

1.7​

1.7​

4​

3.5​

3.3​

3.1​

3​

2.4​

2.1​

1.8​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

3​

3.2​

3.1​

3​

2.4​

2.1​

1.9​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

1.7​

3​

3​

3.1​

2.4​

2.1​

1.9​

1.7​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

2​

2.4​

2.4​

1.9​

1.5​

1.4​

1.4​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1.6​

1​

1000​

1200​

1500​

2000​

2500​

3000​

3500​

4000​

4500​

5000​

5500​

6000​

7000​

8000​

9000​

10000​

<--RPM​

[FONT=&quot]Another thing to remember is that the Closed Loop system is only activated once the engine is up to a predetermined temperature.

So simply put, adding a variable to the equation such as the change in the exhaust will definitley affect your afr. When in open loop control the ecu uses the fuel table that the engineers made from factory with the factory parts. Obviously in your case the afr is probably not afftected enough to cause you any noticeable symptoms. Its totally your choice on what you decide to do, we just give advice from a practical sense. As you can see from my example graph, there is plenty of time that the bike is no longer in closed loop control and its running on a programmed set of values, with your modifications the engine will require a different set of values to operate at the correct afr. Like I had said, it may be close but there could be a point at where it goes lean enough you may cause damage. That is a risk I would not be willing to take.

But this is just advice and take it for what it is, ultimately it is your decision on what you want to do in the end. [/FONT]

 

[Drstimpy]

That’s really cool information...you have a fun job!
I was wondering where the close loop open loop switch happened....interesting how it is very engine specific.

My duke 690 ran like crap stock with stuttering and generalized unhappiness under 4500 rpm so my hand was forced with a Kev O2 mod that helped. My 390 has never really behaved the same way and perhaps it’s because it’s spending more time in open loop as you say. Though I’m sure the fueling isn’t perfect in open loop, it isn’t continuously trying to lean it out more in the closed loop...like my 690 was.

All in all, if I’m going to spend 10-15% of my purchase price on PCV and tuning, I want to be able to perceive a big, positive gain. I’m worried I won’t. Because it just isn’t very bad now. I’m also worried about selection bias because the people who have spent $500-$1000 on these modifications are going to exaggerate the benefits. If there were a lower cost alternative for people that just want to be safe, I’d use it.

Ps I’m at sea level and about 80 degrees that day. Maybe I would notice more symptoms if it was colder outside ,but you would expect the open loop to compensate for that as well.


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[mattv]

If there were a lower cost alternative for people that just want to be safe, I’d use it.

I came across this in the past: https://rapidbike.us/products/rb-easy-ktm-390-duke-rc-2012-2017

I don't know much about it, though. But, if you're not experiencing the lean surge at low RPMs, maybe it's not worth it [FONT=&quot]¯\_(ツ)_/¯

[/FONT]If you're still curious, maybe somebody can loan you an AFR gauge.

 

[Drstimpy]

Looks a lot like kevs O2 mod for 690...


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[Formula390]

[FONT=&amp]But this is just advice and take it for what it is, ultimately it is your decision on what you want to do in the end. [/FONT]

Exactly.

Drstimpy, running on the Dyno to test your modifications isn't just to get your HP but your AFR. If you aren't getting this feedback, you are poking at something dangerous in the dark with a sharp stick. You have a number of people here, all basically telling you the same thing, and all from a basis of many years of experience with THIS SPECIFIC MOTORCYCLE. The 390 is a unique beast, and has a number of peculiarities unto itself. I to have far too many motorcycles and years under my belt and have not had the sort of issues we REGULARLY deal with for the 390. Bajaj and KTM made a great bike, but it has a few VERY well documented concerns, which are all quite easily addressed. I would not design an exhaust without access to a Dyno and the AFR. Doing so is asking for Bad Things(tm)! Using your experience with prior motorcycles is NOT a safe way to proceed. Do so at your own risk level... but know disregard of the forum experience is begging for an expensive failure. $0.02.

 

[Formula390]

I’m just really having trouble understanding how asymptotic lean conditions are going to ruin my life[emoji56] You, yourself state the bike runs lean from the factory and yet parts aren’t blowing all over the roads around the world. Also, aftermarket fueling schemes make a lot of money for a lot of people...including you...no offense...and that fact needs to be expressed in this conversation.

Also, you are making an assumption that I make ANY money from "aftermarket fueling schemes" here. I do not. Not one cent.

I don't sell the power commander, or any other piggyback fueling components. Why? I don't have a dyno and I can't create the maps. I do sell the Tyga exhaust, yes. I do have a map for the Tyga Exhaust, which was made by MattP there at Tyga there at the factory. That map was made with auto-tune and is good for a basic starting point, but not something I recommend using without putting the bike and tuning for a customers specific bike and state of tune. I don't make a cent from any of that. I pivot on my heel and point to those who I DO recommend one buy their PCv from, who can adequately support the unit based on their having a dyno and having the time, and extensive experience, to build these custom maps. People like Chad and Paxton, our other forum sponsors here who have engine development programs.

There is a REASON I recommend the PCv, and there is a REASON I also defer to those who make maps for the 390. I do not profit from this however. I have had many people ask me to carry the PCv and become a power commander reseller. I have not done this, and don't anticipate I ever will. At least for as long as I don't have a dyno. Right now, my energies are directed towards the areas I have experience. Namely, machining parts and suspension, and being the US Tyga distributor.