Stalling issue

[bigbird]

Talk of stumbling and stalling of the NC engines is rather new here on the forum. With wwriz’s comments noting at least the second 2021 model stalling example, I wonder now if the fueling has been changed for the 2021 models.

With going to Euro 5 requirements, a lot has changed with the '21 MY.
Drive by wire with the resultant electronic control of the throttle valve would result in all kinds of changes made to the intake and fuel systems.
Likely ignition has been remapped as well with the change to the different valve timing between cylinders.
This issue sounds like something that may have to be investigated by the engineers in Japan.

 

[wwriz]

I just bought a new 2021 NC750X DCT. I have over 400 miles on it and the bike has stalled on me 5 times now. Today after riding 50 miles on the freeway, then riding in stop and go traffic, taking off from the light the bike will either hesitate, or stall. The more miles I put on the bike the more it happens. It has stalled 5 times now. I took it to the shop, the mechanic said it is all computerized, there is no adjustments. WTH... Does anyone have this problem?

I have a 2021 and it stalled once at a stop sign so far. Bike has 620 miles and stumbles just off idle hot or cold. Acts like its lean. When running at any rpm other than idle it runs and carburates well. I think a tweak in fuel mapping may help. I will check for any vacuum leaks.

 

[670cc]

With going to Euro 5 requirements, a lot has changed with the '21 MY.
Drive by wire with the resultant electronic control of the throttle valve would result in all kinds of changes made to the intake and fuel systems.
Likely ignition has been remapped as well with the change to the different valve timing between cylinders.
This issue sounds like something that may have to be investigated by the engineers in Japan.

The possibility of fuel mapping changes for 2021 is reasonable to expect based on the factors you described. Except . . .

Regarding the “the change to the different valve timing between cylinders”, from my research and memory, this is nothing new. I realize Honda has recently touted this feature in 2021 marketing materials, but they also did so back in 2012. Many of those approximately 10 year old documents can no longer be found on the internet, but the wikipedia page makes reference to valve timing difference between cylinders when describing the original NC700 series engine: https://en.wikipedia.org/wiki/Honda_NC700_series. The wiki article includes 3 citations to support that statement. The Honda one I can no longer find, but an independent article cited makes mention of the valve timing difference back in 2011: https://newatlas.com/honda-integra-700-twin-cylinder-superscooter/19945/

From the article linked above and published September, 2011:
“ The engine uses branch intake ports inside the cylinder head so there is only one intake channel for both cylinders. It is designed to create deliberate interference between the intake processes of the two cylinders, and the rest of the engine is designed to use this to give it the above-mentioned engine character which sounds like it might be something special. Apart from varying the combustion timing in each cylinder, there are also changes to the valve timing between the two in-line cylinders. In deciding this was necessary, Honda then used one camshaft deliver two timing routines for the intake valve.”

So maybe Honda has again revised valve timing for 2021, but the timing being different between the two cylinders is not new.

Calling dduelin and his binder of all documents NC. I’ll bet Dave has this info in his library.

 

[bigbird]

So maybe Honda has again revised valve timing for 2021, but the timing being different between the two cylinders is not new.

Not maybe; they did revise the timing.

 

[dduelin]

The Honda press release on the 2021 NC750X attributed increased power of 2.7 hp and a red line boost of 600 rpm is due to revised valve timing and increased intake/exhaust efficiency.

The 2012-2020 NC700/750 engine has always had different valve timing for each cylinder which is unusual for multi-cylinder engines but the 2021 revision is the same but different as Yogi Berra would say.

 

[MolsonMuscle]

Almost up to 750 miles on my ‘21 and, while it hasn’t stalled, it does sometimes stumble for a split second when starting from a standstill. I noticed that right after I bought it and rode it 100 miles home.

I had a CTX700 DCT a few years ago and it didn’t do this ever. But the CTX was much more sluggish off the line than the new NC. I’ve gotten used to the throttle mappings on the NC now and I don’t notice the stumbling as much. Also I use rain mode a lot and it seems to reduce the stumbling off the line significantly.

 

[Bob S.]

I brought in my NC to the shop today for its 600 mile service and stalling problem. They said there are no adjustments. But they did reset the computer, and told me to use Premium Fuel. So I will let you know if this helps with the stalling.

 

[Deleted member 1183]

I brought in my NC to the shop today for its 600 mile service and stalling problem. They said there are no adjustments. But they did reset the computer, and told me to use Premium Fuel. So I will let you know if this helps with the stalling.

Tbh this "no adjustment" attitude doesn't wash with me in a situation where the bike is under warranty. There could be any number of things causing the issue, possible injector issues, possible ECU issues, battery issues etc etc. It seems that unless the problem is staring them in the face, some modern mechanics don't seem to want to try to trace problems nowadays. If I were You I would not accept that attitude. I would simply point out that there is a problem, the bike is under waranty, so fix it, end of !

However, hopefully the reset and the premium fuel will solve the issue. I would have thought though that these bikes should be able to run on standard fuel, especially if one were to do a world trip on one.

 

[670cc]

I brought in my NC to the shop today for its 600 mile service and stalling problem. They said there are no adjustments. But they did reset the computer, and told me to use Premium Fuel. So I will let you know if this helps with the stalling.

The NC does not require premium fuel. Read the fuel recommendations in the owner’s manual. Premium can’t hurt it, but won’t help it either. This shop was successful in getting you out of their hair and sending you on your way, but do not expect their action and advice to make the motorcycle run any better. This shop basically did nothing to address your stalling problem.

 

[bigbird]

Hopefully, resetting the computer will solve the issue.
The shop has no idea what they're talking about as soon as they tell you to run premium fuel.
If you've opened a case with the distributor, make sure and update them with the dealer's ridiculous suggestion if the computer reset doesn't work.
The regional tech rep must be consulted by the dealer at this point if the shop foreman or lead tech is stumped.

 

[Bob S.]

I took a short ride for breakfast this morning, my NC stalled at a stop sign when I gave it the gas to go. So the resent to my ECM did not work. I doubt if premium fuel will make a difference, but I will try it on my next fill up.

 

[670cc]

I took a short ride for breakfast this morning, my NC stalled at a stop sign when I gave it the gas to go. So the resent to my ECM did not work. I doubt if premium fuel will make a difference, but I will try it on my next fill up.

It's rude to point it out, I know, but I said in post #29 that the dealer's "work" would make no difference.

Premium fuel comes into play for lessening the occurance of detonation/pre-ignition when cylinder filling and compression pressures are near maximum. If your NC stalled at a stop sign, increasing the octane level of the fuel is not likely to make any difference.

 

[Bob S.]

I’m about to take a loss, and buy and another BMW. Their service departments are top notch.

 

[MolsonMuscle]

I’m about to take a loss, and buy and another BMW. Their service departments are top notch.

So sorry to hear about the stalling issue. I wonder if there’s a lemon buyback law that would apply here, considering they’re unable to fix it. I guess the rules vary by state. Honda should really get involved and fix it.

I also think I mischaracterized the issue I have with the bike stumbling off the line. I paid closer attention today and noticed the clutch doesn’t engage until the motorcycle is a bit more revved up than the previous DCT I owned. This gives it faster pickup but is a weird feeling because the bike doesn’t move immediately whwn I open the throttle. Takes some getting used to. Sorry to conflate these two issues.

What you’re experiencing would make me want to sell too. But I don’t think you should have to take a loss on a defective bike.

 

[Bob S.]

I have a claim open with Honda USA, but they never got back to me. I will call them tomorrow. If that doesn’t work, I will look for an attorney to talk to.
I have not owned a car since 2010, I ride everyday so I need a Bike that is dependable.

 

[bigbird]

I have a claim open with Honda USA, but they never got back to me. I will call them tomorrow. If that doesn’t work, I will look for an attorney to talk to.
I have not owned a car since 2010, I ride everyday so I need a Bike that is dependable.

Legal representation would get Honda off their ass. Stalling is a huge safety issue.

 

[Bob S.]

This screen shot is from Honda's website.

 

[Bob S.]

I talked to Honda USA Powersports today, they said that none of the dealers service shops notified Honda of my stalling problem. They said I need to drop off my bike at the service department and leave it until they duplicate my issue. Ok, the shop is so busy, they might ride it around the block then let it sit, they have paying customers that are more important. Being this bike is my only transportation, that won't work. So I talked to an Attorney today, about the Lemon Law for here in California, the vehicle must be in inoperable or in the service department for a minimal of 30 days, or you have taken the vehicle to the service department a minimal of four times for the same problem to qualify for it to be Lemon. So I will do that. Thats too bad, I really like riding this NC... I should of waited for the 2022 model for Honda to work out the kinks.

 

[MolsonMuscle]

What an ordeal! Not sure which dealer was telling you to use premium but maybe try a different shop and see how it goes. There’s lots of reputable Honda dealers in the Bay Area—SF Moto and Berkeley Honda are two that come to mind. I’m sure they’ll be able to reproduce the issue. And if they do find the problem maybe they can fix it. It’s under warranty so you’re covered.

 

[Bob S.]

Unfortunately, the Honda service departments charge me $75 to pay the mechanic every time I bring in my bike for this stalling problem because they cannot duplicate my stalling issue. This is a real nightmare.