De-Cat and Air Filter

[Reyno]

I just fitted a de-cat pipe and DNA air filter, I've not replaced the silencer so I'm still using the Honda can.

My engine feels less bogged down and it accelerates a little quicker but my top end (max speed) has been reduced by 10%, what's going on?

Also will I notice and increase in performance if I change the Honda silencer for a Scorpion?

thanks.

 

[casualmatt]

In my experience with motorcycles, which includes quite some time as a professional Ducati mechanic, I have always been convinced that when you modify exhaust in any way, it is a trade off. If you gain in one area, you will always lose in another. In my opinion, there is no header/muffler that will improve your performance at all RPM ranges on any vehicle. What you are describing is that you gained torque(acceleration) at low and mid range RPM and lost horsepower(max speed) at higher RPM. To me, that sounds normal. Also, when you put on a filter that flows more air without some form of fuel injection modification, you made the bike run slightly leaner. Remember that this is on a bike that is already set up to run lean from the factory both for emission standards and fuel economy. That might also be affecting your top end loss.

 

[Lou Wambsganss]

THat is a big change to the way the engine moves air. The effects are more noticeable at high RPM since that is when the engine is moving the most air. You would probably see a benefit from installing a Fuel Controller such as Bazzaz. As far as I know, they are the only one on the market so far for the NC700. Power Commander is not available yet.

Most people whop just change a muffler or air filter will not see a significant improvement in performance by installing a fuel controller. However, installing a CAT delete pipe and aftermarket air filter probably has enough of a total change to make the fuel controller worthwhile. Our bikes use a narrow band O2 sensor and an open-loop fuel program. This means that the bike cannot fully adjust to major airflow changes. It can only make minor adjustments to account for fuel types, temperatures, engine load, etc. The Bazzaz controller and map are tuned to supply more fuel in most of the RPM range, and actually slightly less at WOT at high RPM.

I know a lot of us, myself included, would be curious to hear your results if you install the Bazzaz unit. There has been some talk about it in the past, but not many people thought it worthwhile. You, however, are one of the few who could probably actually see a benefit.

 

[Todd L.]

I have the de-cat with stock can and stock air filter and have no reduction in top speed. Did you reset the ECU? The DNA air filter is like a K&N on steroids, so you may be at the point where you need the Bazaaz fuel controller. According to the posts I've read from Bazaaz themselves, our bikes are actually rich in the top end and Bazaaz reduced fuel in that range for more power. The low-mid range area was very lean from the factory and they increased fuel. Do a search on here for the Bazaaz and you can read about it. Since our bikes are actually rich in the top end, I think you need to reset the ECU or wait for the computer to do it eventually on it's own. I didn't do the reset procedure and just let the bike remap itself. If you replace the stock muffler too you will really benefit from fuel programming. The PCV has been cancelled from Dynojet because they weren't smart enough to find a way around the O2 sensor like Bazaaz did. E-mail them for an answer and that's what they'll tell you.

 

[itlives]

Maybe it's my age but I'm happy with my NC just like it is.
When I read of all the "try this, now you have to try that" stuff to try for a little better performance, I'm glad I'm satisfied.

 

[maxwellian]

Folks always say modern engines run lean, but I thought a cat only works if the mixture isn't lean. Maybe it stays hot enough being so close to the engine, doesn't need so much fuel to keep the reaction going?

 

[ray]

I have tried DNA air filter, LV de-cat header and end-can combo. Loss of low-end torque but strong above 4krpm. But not suitable for my riding pattern, so reverted to DNA, LV header and stock end can.

 

[Reyno]

I have the de-cat with stock can and stock air filter and have no reduction in top speed. Did you reset the ECU? The DNA air filter is like a K&N on steroids, so you may be at the point where you need the Bazaaz fuel controller. According to the posts I've read from Bazaaz themselves, our bikes are actually rich in the top end and Bazaaz reduced fuel in that range for more power. The low-mid range area was very lean from the factory and they increased fuel. Do a search on here for the Bazaaz and you can read about it. Since our bikes are actually rich in the top end, I think you need to reset the ECU or wait for the computer to do it eventually on it's own. I didn't do the reset procedure and just let the bike remap itself. If you replace the stock muffler too you will really benefit from fuel programming. The PCV has been cancelled from Dynojet because they weren't smart enough to find a way around the O2 sensor like Bazaaz did. E-mail them for an answer and that's what they'll tell you.

I did the ECU reset but I now believe that it doesn't do anything since my 10% top end loss is no more and I now have a 10% increase some 100 miles later. I believe my ECU has adjusted itself in its own time, actually the bike seems to change its character and habits every time I ride it, yesterday 3rd gear felt flat as did 6th but today they all felt fine, only problem now is I've lost a bit of low end in 1st and 2nd.

I've got Bazzaz coming back to me to advise about their fuel controller and if it will work well enough with my bike as it's a DCT, I'm suspecting not. My DCT was really unhappy the first two days without the cat and standard air filter but it's now as smooth as ever, again I think any reset method done without software is a myth or we're all doing it wrong? I've only been able to find one advised method of doing it :

Disconnect battery for at least 30 minutes followed by turning on the ignition before reconnecting.
Allow to idle until the fan kicks.
Hit kill switch.
Turn off ignition.

Maybe it's my age but I'm happy with my NC just like it is.
When I read of all the "try this, now you have to try that" stuff to try for a little better performance, I'm glad I'm satisfied.

It's all part of the fun and the journey unless of course your vehicle is no more than a tool. I've nearly always enjoyed myself making vehicles more reliable, more powerful and prettier, I'm seriously impressed by my NC and I'm sure I'll be able to get all of the extra power I'm looking for because it's not far off now.

 

[showkey]

I think your right the ECU reset and changing the FUEL MAP is a myth. The fuel MAP on tha NC is not that wide......and stock fuel system has no or limited learned trim values.

I also think BAZZAZ concluded the Honda did a pretty good job on the stock Fuel MAPPING and they could make very little improvement........plus it cost a bunch of money for little or NO improvement or even a decline in performance as you have found.

I also think your "seat of the pants dyno" is not reliable indicator of performance gains.. BUT
BAZZAZ dyno charts were less than impressive.......especially when see what they charge for these modest to nonexistent gains and or potential problems.

Then you add your bike is DCT........that adds a whole new level do complexity to tuning.

Good luck.........

 

[Reyno]

Not what I wanted to read showkey but it is what I'm suspecting too. Over the next week or so I will be trying combinations of air filter and exhaust to feel the difference for myself, I've never been a firm believer in air filters making much of a difference over stock, I've pulled some seriously clogged filters only to find the engine runs the same with a new one and only ever noticed a difference in sound and not responsive power when using K&N filters. I would have thought if the NC reacts well to improved air flow it would contradict the very limited air flow adjustment theory? anyway I will be trying the DNA filter + Honda cat exhaust, then I'll go back to Honda filter + Honda cat exhaust, then Honda filter + de-cat by which time I should have heard from Bazzaz and if they aren't highly recommending the fuel controller I'll get a Scorpion end can and find a combination that suits me best. Also I'll be visiting my local race tuning specialists to see what they think and possibly set up some dyno runs, I'll keep the thread updated.

 

[Todd L.]

I also believe the ECU reset could be myth, and that's the reason I didn't do it myself. But there are many people on the UK forum who had a DCT with shifting problems that were cured by doing the rest, so who knows. Since you have a DCT I bet that is the reason things are different for you. The computer has shift points programmed based on the factory settings, and unlike a manual you have no control over how it will react to the changes. Since it is a much more complicated system, the results are unpredictable. Arrow has a full exhaust system and a dyno chart to show its impact, and no where is there a power drop in the low end or anywhere. If I had a DCT I honestly would be scared to change anything. On my manual I couldn't be happier with the decat, with better power everywhere and a nice mid-range surge when you open it up. Try just using the decat with stock filter and muffler. It's a much better choice than just changing the muffler unless all you want is more noise. I'm sure the Bazaaz would make you happy, but the installation for the DCT is much more complicated than the manual if you look at their instructions. As long as you're comfortable with the installation give it a try. Or just trade in your DCT for a manual!

 

[wozza]

Have you tried just using your bike in manual mode for a few trips to see if there's any difference?
I'm just wondering if the bike is in manual mode then it isn't programmed to change gear at a certain point.

 

[Reyno]

Today I had the bike put on a rolling road but wasn't able to have the test completed as the bike wouldn't move out of 1st gear.

It would switch from N-D-S and AT-MT but would not change past 1st, the ABS light was on so I suggested turning it off and putting it back on the dyno but the technician wasn't happy about subjecting the DCT to the unusual drive steps of the roller and feared the DCT could get confused and damage could occur.

He's asked me to find out more information on the dyno procedure for DCT bikes but I can't think of anywhere to ask other than here or Bazzaz.

 

[ray]

Thought it should work as the speed sensor is on front wheel

 

[Todd L.]

I remember from early periodicals on the DCT that you couldn't put one on the dyno. That's why early reviews of the DCT could only go by the manual's power rating on the dyno. Manual has 51 bhp vs. the DCT's 47 bhp, but when on the dyno the manual has 47-48 rear wheel power so it makes sense. It has to do with a sensor on the front wheel. The front wheel must be spinning for it to work which is not possible on the dyno.

 

[wozza]

Out if interest which decat pipe did you fit, the Arrow, or the Leo Vinci? The Leo Vinci has what looks like a cannister fitting where the cat was, whereas the Arrow seems to be just a straight through pipe. I know people on the UK forum who have used the Leo pipe are very happy, whereas I haven't come across anyone fitting the Arrow decat pipe yet.

 

[Reyno]

Out if interest which decat pipe did you fit, the Arrow, or the Leo Vinci? The Leo Vinci has what looks like a cannister fitting where the cat was, whereas the Arrow seems to be just a straight through pipe. I know people on the UK forum who have used the Leo pipe are very happy, whereas I haven't come across anyone fitting the Arrow decat pipe yet.

Hi Wozza

I've got the Leo Vince pipe

 

[wozza]

Ah right then. I wonder if the problems are purely down to your bike being DCT. I haven't heard of anyone (other than you) fitting a decat pipe to either the 750, or DCT.
You're probably the first on both counts.