Engine Fluttering Sound

[SergeantChuck]

Confused on what that is in your picture ? I thought you have. 2013 model ?

The O2 sensor on the NC is directly above the item in your picture at least on 2012-2013 model.

Item 12 in the parts diagrams

View attachment 37934

View attachment 37935

Edit after MZ5 post: is that the O2 wire harness hanging off the edge of coolant recovery bottle ????

Yes, the harness runs through a slot in the recovery bottle. At least mine does.

 

[SergeantChuck]

Yes, what showkey said^^^
It doesn’t appear (I’m looking at a small screen in bright light) that you’ve disconnected the O2 sensor.

If or when you do disconnect the O2 sensor, the ECU will be forced to run in open-loop all the time. Aside from any codes, it will run based on pre-programmed fuel maps. There is no learning and no time delay for an adjustment in this mode. Fueling and thus running quality should be pretty good in this mode, but not quite optimized (at least from an exhaust emissions point of view).

***EDIT***
Upon further review, maybe it is the connector from the O2 sensor that’s hanging down? I’ve decided I can’t tell.

Haha, The hanging harness leads up to the round heat shield that protects the O2 sensor. It is still unplugged and no lights after 90 miles now. Rode bike again today. Still runs the same as it did prior to unplugging. Exactlyt the same.

 

[SergeantChuck]

^^^^^^^^^Not sure I agree on not going to the dealer, I understand the lack of trust, cost, inconveniences............but........ good Honda trained tech witha Honda factory scan tool could verify every sensor in 3 minutes time by looking at the live data. There would be no guessing if the air (IAT) and water temp (ECT) sensors are working, the MAP and O2 values would be verified, throttle position sensor and Idle air controller ( IAC) checked, injector duration checked and the fuel pressure would be indirectly verified by the fuel trim and O2 wave pattern.

I do agree finding a good tech with that tool that knows what good and bad data stream looks like could be a challenge.

I don't disagree. Unfortunately, I have good reason not to trust the shop where I bought my bike. Maybe it's because they don't work on them enough but they really jacked mine up twice. I'll have to find another and the closest is about 1 hour away from where I live.

 

[showkey]

Another data point.

Unplugged my O2 went for a ride. No check engine light and the engine performance was unchanged.

Shop manual also states if the O2 sensor codes..........engine performance is not affected.

 

[SergeantChuck]

I'd like to clarify something. I decided to investigate another avenue. I read a couple post from a few years ago where guys had a cam chain tensioner spring break. I decided to recheck my timing marks. On page 3-10 of the manual it says to make sure the "1" mark is aligned with the "lower" cylinder head index line.

To me, the lower line is the line closest to the rear tire. Both lines are more to the side of the hole than the top or bottom BUT they would be one above the other if the heads were vertical. So, in my opinion, the line on the left of the hole (nearest the rear tire) is the lower line.

I bring this up because my "1" and "2" mark were both aligned with the line closer to the front tire when I had both the 1T and 2T marks lined up on the index notch.

 

[Jt105]

The cam rotates 1/2 turn for every 1 full turn of the crankshaft. You may have the piston at TDC, but on the exhaust stroke. This would explain the mark lining up opposite from what you expected.

If the cam was truly 180 degrees out of alignment, the engine would not run.

JT

 

[670cc]

I'd like to clarify something. I decided to investigate another avenue. I read a couple post from a few years ago where guys had a cam chain tensioner spring break. I decided to recheck my timing marks. On page 3-10 of the manual it says to make sure the "1" mark is aligned with the "lower" cylinder head index line.

To me, the lower line is the line closest to the rear tire. Both lines are more to the side of the hole than the top or bottom BUT they would be one above the other if the heads were vertical. So, in my opinion, the line on the left of the hole (nearest the rear tire) is the lower line.

I bring this up because my "1" and "2" mark were both aligned with the line closer to the front tire when I had both the 1T and 2T marks lined up on the index notch.

There was an early version of the 2012 Honda service manual that had the description of the camshaft markings reversed. That may or may not impact your concerns about the marks.

 

[SergeantChuck]

An update for those that were watching this thread. The NC has decided to start running better all by itself. About two weeks ago, I started the bike in the parking lot and was headed for home. The on-ramp to the interstate is uphill so it requires a little more throttle than level ground and I can normally feel a decent little shake while accelerating. This time the shake was barely noticeable. I immediately began to question myself if I was imagining things so started riding the bike a bit more harshly. Sure enough, there was a major difference. She still isn't 100% but dang close.

 

[1wiseguy2]

An update for those that were watching this thread. The NC has decided to start running better all by itself. About two weeks ago, I started the bike in the parking lot and was headed for home. The on-ramp to the interstate is uphill so it requires a little more throttle than level ground and I can normally feel a decent little shake while accelerating. This time the shake was barely noticeable. I immediately began to question myself if I was imagining things so started riding the bike a bit more harshly. Sure enough, there was a major difference. She still isn't 100% but dang close.

HUH???? major head scratcher! Maybe a loose connector? Well let's hop it keeps healing itself!

Sent from my SM-N960U using Tapatalk

 

[D_SC]

Anything else to report since the last update SergeantChuck?