Losing One Cylinder

[Naked_Duc]

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.

That's pretty incredible!

 

[showkey]

Another data point...........Similar plugs in Honda car and trucks are replaced at 105,000 miles.

 

[kpinvt]

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.

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!

I think I'm hearing a distant bell ringing softly. There was something I read a while back about fuel injectors on the NC causing problems. I can't remember where I saw it.

 

[showkey]

Response to the above post^^^^^^^^^^^^The was one report of the a loose ( soft set, not plugged in completely) electrical connection on a fuel injector that I remember.

If the OP bike has any accessories it would be a good idea to check all electrical connection and ground connections for a soft set condition.

 

[rippin209]

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.

My 2012 is almost at 50,000 I'm still on the original plugs. I just got the cheap replacement NGK 3764 I'm installing them next weekend with allot of other maintenance work

 

[670cc]

My 2012 is almost at 50,000 I'm still on the original plugs. I just got the cheap replacement NGK 3764 I'm installing them next weekend with allot of other maintenance work

Likewise. I have no intention of changing mine before 50,000 miles. As showkey said, spark plugs in cars and truck routinely go 100,000+ miles.

 

[rippin209]

Likewise. I have no intention of changing mine before 50,000 miles. As showkey said, spark plugs in cars and truck routinely go 100,000+ miles.

it has been discussed there is possibly a difference between the plugs made for a car and those made for a motorcycle. I got my replacement plugs from Napa for$12 for 2 and that was for the iridium ones so it's cheap enough you could do them on schedule, but personally after hearing those cheaper ones work just fine I wouldn't pay the $45 the dealership wants per plug

 

[Deleted member 1183]

In a low revving long stroke motor like the NC, plugs should not be a problem with 35,000 miles. My focus would be on a temporary blockage of an injector or a loose connection, both of which were suggested above. I have had plenty of experience of injector problems with KTM 690's although the petrol pump was a problem with that also.

 

[ste7ios]

There is no need to purchase the spark plugs from the OEM channel. You can purchase them from the market at the half price...

e.g. https://www.amazon.com/NGK-IFR6G-11K-Iridium-Spark-Plug/dp/B005NB9ICM

 

[670cc]

The GL1800 OEM spark plug works in the NC700, too. NGK BKR6E-11. They last 32,000 miles. $8 for a box of 4, free shipping in the USA.

https://www.amazon.com/NGK-BKR6E-11...=UTF8&qid=1486834882&sr=1-1&keywords=Bkr6e-11

 

[rippin209]

$7 or $8 each at Napa

 

[ste7ios]

BKR6E-11:
BK=Thread Dimensions: 14mm / 5/8”(16.0mm)ISO Type
R=Resistor Type
6=Heat Rating
E=Thread Reach: 19.0mm (3/4")
11=Spark Gap: 1.1mm (.044”)


BKR6EIX-11:
As the above plus
IX=High Performance Iridium (0.6mmØ)


IFR6G-11K:
I=Premium Iridium
F=Thread: Thread Dimensions: 14.0mm, Thread Reach: 19.0mm, (3/4”), Seat Type=Gasket, Hex=20.8mm, (13/16”)
R=Resistor Type
6=Heat Rating
G=Firing & Construction special code
11=Spark Gap: 1.1mm (.044")
K=Vibration-resistant Ground Electrode


https://www.ngksparkplugs.com/assets/design_symbols_plugs.pdf


There are some similarities but there are also some differences. I wouldn't play with the specs on a modern engine...


To cut the cost I would choose a spark plug with the same specs but from another brand, like Denso... But from my research there are no alternatives...

 

[MZ5]

Be careful comparing spark plug life to the lifespan of automotive plugs. My Honda pickup engine turns ~2,000 rpm at 70mph. My Honda NC700X turns nearly twice that fast, so even if the plugs were the same item, I wouldn't expect the bike's to run more than about half as long as the pickup's. That would be approx the same number of firing events.

 

[Naked_Duc]

Spark plugs (IFR6G-11K) on order via Amazon. It will be here in 2 weeks. Until then, good night!

 

[showkey]

Be careful comparing spark plug life to the lifespan of automotive plugs. My Honda pickup engine turns ~2,000 rpm at 70mph. My Honda NC700X turns nearly twice that fast, so even if the plugs were the same item, I wouldn't expect the bike's to run more than about half as long as the pickup's. That would be approx the same number of firing events.

Agree^^^^^^^ but...........also note that automotive replacing at 105,000 is a maintenance interval, the plugs do not necessarily go bad at 106,000. The modern auto has sophisticated misfire detection and the slightest fire throughs a check engine light. During EPA durability testing no routine parts are changed unless specifically defined in the maintenance book. The engine must pass the emissions test after 105,000 and the slightest miss fire would cause an emissions failure.

Most likely the modern high end ( fancy tip material and construction) plugs are more susceptible to carbon and deposit build up from fuel related issues versus electrode wear. Back in the day worn plug electrodes and weak spark systems were the weak link. Simple plug inspection will tell the user a lot. Of course plug fouling from fuel mixture problems or excessive oil burning is a different problem and the plug inspection would be a key indicator.

That said, thats why there are many plugs with various tip materials are used to last these long extended intervals.

As far as the OP's problem..........I would doubt the plugs are the root cause.

 

[MZ5]

Agree^^^^^^^ but...........also note that automotive replacing at 105,000 is a maintenance interval, the plugs do not necessarily go bad at 106,000. The modern auto has sophisticated misfire detection and the slightest fire throughs a check engine light. During EPA durability testing no routine parts are changed unless specifically defined in the maintenance book.

All true.......and I expect the same applies to our emission-controlled NCXs. Durability requirement for >280cc motorcycles post-2010 is 30k miles. So, 100k for cars & pickups, 30k for motorcycles, and the plugs are spec'd for replacement shortly thereafter. Interesting, eh?

As far as the OP's problem..........I would doubt the plugs are the root cause.

Agree completely. My guess is that it's probably electrical, but it's not the plugs.

 

[Mi_ka]

modern cars usually use the plugs not only as a spark producing mechanism but also as a sensor by providing a bias voltage (80V?) and checking the conductivity that is affected by the presence of combustion related charged particles to check (and adjust) for pre-ignition knocking or for misfire

from what I have read around, this technology has not yet been employed in motorcycles while it is been decades since it first appeared on cars - maybe the less restricted smog regulations and the higher state of tune and narrower envelope of motorcycle engine output requirements put less pressure on manufacturers until now

from what I know, the NC has no such plug sensing in place

 

[AsureDawn]

modern cars usually use the plugs not only as a spark producing mechanism but also as a sensor by providing a bias voltage (80V?) and checking the conductivity that is affected by the presence of combustion related charged particles to check (and adjust) for pre-ignition knocking or for misfire

from what I have read around, this technology has not yet been employed in motorcycles while it is been decades since it first appeared on cars - maybe the less restricted smog regulations and the higher state of tune and narrower envelope of motorcycle engine output requirements put less pressure on manufacturers until now

from what I know, the NC has no such plug sensing in place

Almost definitely not on the 2012 model--it may be smart, but it's not that smart.

 

[Naked_Duc]

FOLLOW UP TO THE OP:

I finally got around to replacing the spark plugs. I got the NGK IFR6G-11K off Amazon. $14 for the pair. The process of replacing was far easier than I had anticipated. It literally took me 5 minutes.



After 34K miles, the original plugs look pretty good. Just a little worn. Checking the gaps, one of the plug is slightly out of spec. It's a little wider than 1.0mm. I don't know if this, in conjunction with crud in the gas, had contributed to temporarily losing 1 cylinder.

After plug replacement, I don't think there is much difference in performance. It might just be my imagination if there is any detectable difference. I would say the engine is smoother during hard acceleration, especially above 3500RMP, with less felt vibration.

Anyway, the bike is back to normal. I will see if mileage would improve. I've seen my mileage gradually dropped by about 5% versus the same time last year with similar riding condition and weather (I track all that on Fuelly).

 

[Mi_ka]

I'd say that 5% is too low to be considered any different out of a lab... Now, 1mm-1.1mm is the gap mentioned in the greek NC700 owner's manual so you should get pretty much away from this number to have weak fuel failing to ignite or have any weak coil symptoms show up - when the driving circuit is healthy it can easily bridge wider gaps producing even more effective sparks until the gap gets really wide and the higher jumping voltage can no longer be properly obtained. How much wider, I do not know exactly for such an engine as on the NC. If it is of any value, on my 0.7mm specified 2 stroker I had no problem with occasional 1mm+ gaps.

So, I'd say again, if she purrs ok, and no big trip scheduled over the next weeks, just ride. You can only diagnose some problems when they are manifesting themselves...