Need Help Not sure how to diagnose the issue. Downshifts to first then stalls.

[Vojyr]

Hey! Im new to the forum!

I have no clue how to diagnose the problem I’m having and was unable to find anything related to it. Hoping someone can give some answers or recommendations!

The Problem

After 45 minutes or more of riding, my 2014 Honda NC700 DCT suddenly lost all power to the throttle and started downshifting all the way to first gear then stalled. I could start the bike up immediately after it stalled and ride it back home. Every 20 minutes or so the problem would happen again.

What I thought was the fix.

This is my first bike for reference. Also after this problem occurred we(my riding friend with much more experience and I) looked at the dent in the radiator the seller said was a small dent and that the radiators have a natural curve to them. Once home and looking at radiators they don’t have a curve and the extend of the dent also broke the radiator fan. We determined this was the problem so I replaced my radiator and radiator fan. Made sure the fan was working and was ready to enjoy the road again. Coolant fluid changed and with the problem fluid.

The problem recurring.

I road it 3 days to work with no problems. Work is an hour ride away. One day riding back from a 45 minute drive, it happened again. It happened 35 minutes minutes into the ride and I have no clue what the problem could be now.

The overheating light never came on(if it has one). No clear signs of overheating.

 

[670cc]

There is an overheat light on the dash on your 2014. A bad radiator would be a problem, but the fan probably not. The fan would normally only come on in warm weather if the bike sat idling with mo air flow for maybe 10 minutes. so lets forget about engine overheating for now.

One idea comes to mind mildly based on your symptoms. We have had a few reports over the past 10 years of the fuel pump going bad. I’ll have to find old posts and review, but one was on a bike owned by a guy I knew well, and he was knowledgeable about the NC. Although in his case I think the bike would not restart immediately. (To diagnose, you would probably need to have it in a failed state and test for fuel pressure. If the pump is bad, it is a rather complex repair because the pump is inside the fuel tank and the tank must be removed from the motorcycle to get the pump out).

How about a flaky sidestand switch or kill switch? Those could be tested with a meter. When it dies and you are able to restart, do you exercise or deploy the sidestand during that process?

 

[Vojyr]

First of all thank you for your response 670cc. Hopefully the fuel pump going bad is the last check on the list. Also to many people’s surprise this bike only has 2,833 miles on it. I would be very shocked if it’s the case but events like this do happen for garaged bikes after sitting so long so if I’m led to that, I’ll get it done.

For your questions, I did not deploy the side stand when problem occurred most times. I just flipped on and off the kill switch. I did deploy the side stand for the 2nd instance and the most recent instance after(and only instance after) the radiator repair, because both times I looked around the bike to see if there were any signs I could visibly see of a problem. I’m hoping it’s a faulty kill switch. That was the main thing I’ve noticed to cause remotely similar issues on forums. That will be the first thing I change out and will provide updates.

Many thanks,
Vojyr

 

[lootzyan]

You need a 12V light probe (can be mini-LED) with test leads that you can connect to a insulated wire (you can find it on the web).
Connect the probe to the Emergency Engine Stop circuit and to ground. That way you'll know what's going on while driving.
You need the help of a technician who can analyze the wiring diagram and find the connection points on the wire harness.

 

[INTHEWIND]

Honda DCT's are very sensitive to voltage,
Have you checked your battery cables for tightness and or corrosion?
How old is the battery?
Have you done a load lest to see the batteries condition?
Good luck.

When I brought my bike home after buying it, I installed a SAE connector to the battery for a maintainer to plug into,
The battery cable bolts were finger tight, very loose.
Im happy to find this issue in my garage vs being stranded on the freeway.

 

[ST13Fred]

Intermittent is hardest to diagnose.
Sounds like fuel starvation. Fully charged battery with good CCA is vital to system functions. Honda shop manual is also highly recommended. Loosen and tighten every ground point you can find.
Some F800 BMW owners reported stalling problems with low fuel level; the pump would overheat. Will look at my shop manual and chine in again if I have any further ideas. Good luck.