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Losing One Cylinder

Naked_Duc

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Weird thing happened on the way to work today. Engine all of sudden lost some power and exhaust tone started to sound like a thumper (similar to the CBR1250R I used to have). So immediately I thought I had lost a cylinder. I could still manage to ride along. Luckily, the traffic was heavy so I just keep the RPM high and stay with the slow moving traffic. Occasionally, the power would come back and then go back down. Engine would idle low but that's about it. Made it to work just fine.

It's a 2012 with 35K miles. This had never happened before. I am probably half way to the next oil change. The spark plugs are still original.

So what's causing this? Plugs going bad? Loose coil and connection? Fuel pump going bad?

I will double check the coils before I leave this afternoon. I will probably replace the spark plugs this weekend. It's due for replacement, right?
 
Sounds like a coil, but that is a layman' guess. I have heard once if the coil is going out, it will happen once the motor heats up. Don't know if that is true or not. Let us know the outcome.


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Back when I had my GS500 Suzuki, I had the carb rebuilt because it had no miles on it & it had clogged up. I had exactly the same thing happen and it was a loose wire from the coil....[emoji106]Reattached it and no more problem!


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Now I am really puzzled...

I checked on the coils this evening. Both of them seemed pretty secure. So I pushed on them to make sure they are on tight. One of them may have to moved a tiny tiny bit. Maybe it was my imagination...

The sputtering continued as I rolled out of the parking lot. I thought crap, it's going to be an exhausting ride home in evening commute. Then I remembered I am low on gas. Went and put in 3.5 gallons of gas. According to Fuelly, I have not put in that much gas in 6 months, as I later found out. A couple of blocks down the road, the power started to cut in and out, almost every second the power comes back and then the next second it cuts out. DAMMIT! The morning commute was just 1 cylinder alone.

Got on the freeway and after a couple of miles, the engine would be fine as long as I go above 3000 RPM. Bumper to bumper traffic meant a lot of feathering of the clutch because I never know when the power would come back on.... 5 miles later, traffic starts to open up and I begun to cruise a lot smoother. By the time I am almost home, the 2nd cylinder is back to normal.

So now I am beginning to wonder if it wasn't the spark plugs or coils; it might be the crud at the bottom of the gas tank. This morning I ran the gas tank to the lowest point in 6 months and maybe the fuel pump picked up some crud and clogged up the fuel injector to one of the cylinder. Or maybe that in conjunction with a worn spark plug with weak spark.

Regardless, I am glad I made it home ok. I am changing out the spark plugs this weekend. They are due for replacement anyway, after 35K miles.
 
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That's rough...hopefully new plugs will remedy your problems. Take a good look at the plug wires while you're in there. ;)
 
[...It's a 2012 with 35K miles....The spark plugs are still original.]

Normal change interval for the NC700 spark plugs is 16k miles and I'm sure you could stretch that a little but perhaps not double?
 
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[I am quite sure that the spark plug interval on the NC is 32000 miles.]

Oops, I stand corrected! I misread the service manual chart: at 16k miles it is only an "inspect" and at 32k it is a "replace."

Thanks!
 
My guess would be one of the coils is faulty. As the coil warms up is when it will show the problem. Did your check engine light ever come on? I'm not sure if the NC monitors misfires. One thing for sure, you shouldn't continue to ride it while it's missing. Unburned fuel in the cats can damage them.
 
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I vote intermittent electrical issue (the worse kind), but I would still drain the fuel/replace filter:
coil
lo/high voltage wire short/open
loose connector
weak/fouled plug(s)
computer failure (hitting the rev limiter?)
low system voltage due to alternator/battery issue
rpm sensor failure.
But that's just me sitting here with not much to go on. You need to go through a methodical diagnostic approach unless shotgunning parts works better for you (sometimes it is warranted!). Jim
 
So now I am beginning to wonder if it wasn't the spark plugs or coils; it might be the crud at the bottom of the gas tank. This morning I ran the gas tank to the lowest point in 6 months and maybe the fuel pump picked up some crud and clotted up the fuel injector to one of the cylinder. Or maybe that in conjunction with a worn spark plug with weak spark.

The fuel pump's pick up is at the bottom of the tank. Fuel is always pulled from the tank off the bottom. It's like drinking from a straw in the bottom of the cup. You're always drinking what's on the bottom first. If there was crud at the bottom of the tank, it would be the first thing to be pumped whether the fuel level is low or not.

On the other hand, if there was crud floating on top of the fuel, it would be presented to the pump when the fuel level got really low, but not much floats on the top of gasoline.
 
as others noted, either electrical (plugs/caps/cables/coils or injector/injector drive cables or fuel pump power and ecu but less probable) or fueling (injector/injector filter/fuel pump)

start from one end and work your way to the other dismissing factors along the way
if fueling is involved, some things may be a bit doable by the owner (crude injector declogging) others not so much (hooking a pressure gauge in parallel to the pump to verify it does its work properly while riding around at running temperatures since it maybe ok when cold but not later on)

electrical stuff are a bit funny in their ways: once I had an 14 year old 4-cylinder car starting to intermittently work with 3 and later in the night with 2 cylinders during the same 300 km rural trip with no one hiccup during previous thousands of kms - arrived at destination in nighttime, popped the hatch, put a working light on , checked everything, started the engine and no signs of trouble then turned the light off and voila! various dim fireworks along the spark plug cables towards the engine head after it got up to working tamperature... it seemed that the cables started to suddenly fail after 14 years of no related problems during this particular trip, so changed the cables with whatever cheapo ones I managed to source at the spot and all good
 
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I had a similar issue on my C50 Boulevard 3.5 years ago. I was on a trip to Florida, while going to Key West, when I would hit a bad bump, the engine would cut out on one cylinder. It stopped doing it after a few miles and I forgot about it. No problem again until I was about 2 miles from my home in Indiana. Got home and started troubleshooting. First thing I did was change battery (it was 6.5 years old at the time). Still cutting out on one cylinder. I removed the tank, poured all the gas out of the tank. Started checking all the connectors which were located under the tank. Eureka! The electrical connector to the Fuel Injector assembly had worked its way loose. Completely disconnected all the connectors and reconnected them. Put tank back on, refueled, and no more issue. 20,000 miles later and still running good. When it would cut out to one cylinder, some time the FI light would come on, sometimes it wouldn't.
 
My guess would be one of the coils is faulty. As the coil warms up is when it will show the problem. Did your check engine light ever come on? I'm not sure if the NC monitors misfires. One thing for sure, you shouldn't continue to ride it while it's missing. Unburned fuel in the cats can damage them.

The check engine light never came on. Idle used to be around 1200RMP. During the mishaps, it dropped just below 1000.
 
I vote intermittent electrical issue (the worse kind), but I would still drain the fuel/replace filter:
coil
lo/high voltage wire short/open
loose connector
weak/fouled plug(s)
computer failure (hitting the rev limiter?)
low system voltage due to alternator/battery issue
rpm sensor failure.
But that's just me sitting here with not much to go on. You need to go through a methodical diagnostic approach unless shotgunning parts works better for you (sometimes it is warranted!). Jim

Thanks for the list of possible causes. It will give me some ideas for troubleshooting.

I will start with the plugs, coils, and connection. Seems like the logical first step. I did have a weak battery and was replaced 6 months ago. The headlight went dim and rev dropped with weak power output. I don't think it's the case here. RPM sensor is good and I only live within 3000 to 4000 RPM. Finger crossed it's not computer failure or any wiring issues.
 
wiring issues could just be plugs needing to be removed and reattached to their matching sockets a couple of times as friction can fix eroded metal contacts
 
I took a day off from riding, due to weather. Got back on the bike today and everything is fine. It's as if nothing had happened. :confused:

Half way home on Wednesday, the power was back to normal with some occasional "hiccups". After I got off an freeway interchange, I opened it up a bit with hard acceleration and rev'ed it up to 5500RMP. That seemed to do the trick in clearing everything up. It was 100% normal after that.

Now I am pretty convinced all these was caused by 1) almost worn spark plugs and compounded by 2) very low gas tank where the fuel pump picked up some crud (somehow). The dirty gas resulted in bad fuel mixture which wasn't combusted in one of the cylinder with the worn spark plug. Once I put in more gas, the fuel injector started to clear itself up after about 10 mile or so. By the time I got home, 25 miles or so, the injector was back to normal. Thoughts? It's either that or the motorcycle god is trying to tell me something. Or the infamous electrical gremlin?

Regardless, I am replacing the spark plugs. I will post pictures of the said plugs.

Cheers!
 
Although Honda calls for spark plug replacement at 32,000 miles, NGK says on their Web site that those original iridium plugs should be good for something like 60,000 to 70,000 miles.
 
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