3 questions about the exhaust

Ron Doles

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Hey Guys
I just purchased a 2012 NC700X with 8400 miles on it yesterday.
I have had a couple fuel injected scooters, (Yamaha Majesty and Honda Silverwing) but this is my first fuel injected motorcycle. Both of those scooters had simple open loop FI without an O2 sensor in the exhaust.
1. Do all years of NC700 have an O2 sensor in the exhaust stream?
2. Does the fuel system have enough range to compensate for a lean condition from aftermarket mufflers?
3. I didn't see any O2 sensor on the muffler or exhaust pipe. Maybe I just missed it, where is it?

My bike came with some carbon fibre aftermarket can on it and the exhaust pipe is a bronze color. Not sure if that color is normal or it discolored because the exhaust gas temperature is higher due to the aftermarket can. This can is not excessively loud but the original muffler came with it so I am tempted to switch back anyway.

Thanks for your input in advance.

Ron
 

670cc

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1) All NC700 and 750 engines use a closed loop EFI with O2 sensor.
2) Due to inherent restrictions in the 1 into 2 into 1 cylinder head design, air flow through the engine probably has it’s own limitations. I doubt any aftermarket exhaust could alter the air flow significantly, so I would predict the stock sensor and EFI would work fine.
3) The oxygen sensor is mounted at the input to the catalytic converter, under the lower front cowl.
 

bigbird

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2. Does the fuel system have enough range to compensate for a lean condition from aftermarket mufflers?
I am running an aftermarket can (Delkevic) on my NC750.
The cat converter provides a significant amount of resistance to exhaust gas flow, likely much more than an aftermarket muffler with baffles removed, ever will.
My engine runs the same, whether with stock muffler or aftermarket.
I do get a bit of lean overrun popping on deceleration, which sounds great IMHO.
The 700/750 engine, with its 270 degree crank, sounds so much better with a can than does a parallel twin with a 360 degree crank.
I had a Silverling 600 (360 degree crank) with a LeoVince can, and it sounded terrible compared to the NC.
 

TacomaJD

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Yep, no issues with aftermarket exhaust. The oem headpipe on mine is darker colored that the stainless midpipe of the Yoshimura that I put on it. I assume it's just different metals and tarnish over time. And the oem exhaust on those year bikes is ridiculously quiet, so if you like hearing your bike at all, you won't like the oem can. Like you won't be able to hear it at all going down the road. The 2016 and up models came with a different oem exhaust and has a little more growl to it. Still not "loud" but sounds much better than the older generation oem can. All depends on what you like. I like to hear my motorcycles, but then there are others that want theirs as quiet as possible.
 

mtnbiker1185

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Generally speaking, if you put any sort of cat-back type exhaust system on a machine (be it motorcycle or other vehicle) you won't have to remap it. It is only when you start doing full exhaust system replacements that you will run into issues.

I second wanting to hear my motorcycle. While the DCT makes it kind of a mute point since the bike shifts itself, I had a HD Seventy-Two that you couldn't hear above 45mph with the stock exhaust. With no tach it made it difficult to know where you were revs wise and thus knowing when to shift.
 
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