NC750X DCT shift points. Is this normal??

[Therapy]

Just some follow up: the local Honda dealer tested it, and confirmed: something is wrong. I left the motorbike in the service on 9th Nov, and I did not see it since then They asked the the help of Honda representative after they run out from own ideas. Honda did a lot of measurement, track recording, re-programming, they replaced many parts (whole cable system, sensors, etc.), but they did not find the reason of the strange behavior. I hope they will repair it before summer

That is really strange. I hope they solve it.

 

[lootzyan]

I agree, it must be very frustrating. They should have an answer for you already, especially when they have all right diagnostic equipment.

... for example. I want to overtake a speed of 50, and I give rapid gas, then it switch back to fourth grade from five (that's fine), but after overtaking it stucks in the 4th gear at speeds up to 100-120 / 6-7,000 rpm as well and the +/- switches do nothing, they are not respond. ...

I read again your original tread (#34) and I have a question. You went from speed 50 km/h to 100-120 in what way? Was it one rapid twist of throttle grip until almost full open and you hold in this position or first partial rotation and after that steady acceleration?
If this is one "rapid gas" as you described it, PCM program may respond accordingly. It takes two throttle positions, before and after, and time between those two point then calculates acceleration ratio. Next compares this ratio to preset parameters and selects appropriate gear. If acceleration ratio doesn't change (you keep throttle in the same position) PCM doesn't change a gear because on higher gear acceleration would drop. 100-120 km/h (62-75 mph) are not critical speeds for NC. Maybe this is programmed reaction. Maybe if you'd try different way to overtake: after your rapid gas, when you reach something like 80 km/h, level off your speed. If DCT up-shifts, that's normal reaction. If not - you've got trouble.

 

[Fenyvessy]

I read again your original tread (#34) and I have a question. You went from speed 50 km/h to 100-120 in what way? Was it one rapid twist of throttle grip until almost full open and you hold in this position or first partial rotation and after that steady acceleration?

The problem exist only at "rapid gas". If I use it in retired-stlye very gently, then everything working fine...
They did re-programming PCM, but this "reset" did not change the strange behavior, it seems it is not a software related issue.
I still have not get back the bike from the service until now I hope they can solve the problem before spring

 

[lootzyan]

The problem exist only at "rapid gas"....
They did re-programming PCM, but this "reset" did not change the strange behavior, it seems it is not a software related issue...

I bet that there is no problem at all. They can change DCT, if Honda agrees (I doubt it). More likely they'll give you "sugar pill" reason to make you feel better. When you find out that there is middle way how to effectively accelerate, without turning on hidden afterburners, you will really feel better.

 

[Fenyvessy]

I bet that there is no problem at all. They can change DCT, if Honda agrees (I doubt it). More likely they'll give you "sugar pill" reason to make you feel better. When you find out that there is middle way how to effectively accelerate, without turning on hidden afterburners, you will really feel better.

They confirmed, that the problem is definetly exist. They were able to reproduce it many times.

 

[lootzyan]

They confirmed, that the problem is definetly exist. They were able to reproduce it many times.

If transmission get stuck in one gear and DTC code is not generated that's bad.
Your DCT "must learned" some very bad behaviour.
Sooner or later your service shop guys have to make a decision.

I will try to reproduce the same soon. I'm still in break in period.
Riding about 30 mph give bike rapid acceleration (full throttle?) till about 62-74 mph. What next? To stay on that speed or decelerate with different ratio?
Good reason to use video camera.

 

[Fenyvessy]

Good reason to use video camera.

https://youtu.be/XSeDT2AkAUA

This a video which I recorded in November using my mobile phone, so the quality is horrible bad, but you can see, that until I arrive to highway (around 2:00 in video) it is working fine. After the rapid acceleration it get stuck in 4. gear, so I tried to switch everything: auto-manual, D-S, +/-, but nothing happened until I slow down to the speed which is normal to 4th grade (around 5:00 in the video). After the slow down it is working fine again (until the next full throttle...)

 

[lootzyan]

Bela, I downloaded your video and tried to analyze it in slow motion.
I'm not sure now I'd want to do the same what you did - ride for about 1 min. close to red line.
Acceleration was impressive. From 66 to 120 km/h in 5 sec. and you reached 150 on 4th gear. It changed gear only when you slowed down to 75 and 2800 RPM.
I see you have a problem. But maybe we all have the same problem you just discovered. You may found flaws in PCM programming. It should up-shift when bike is not accelerating but didn't when in 4th gear and over 6200 RPM and later when gradually slowing down.
I think you should take your bike from your dealer and wait for response from Honda. Otherwise they might kill it with this kind of testing.
And let us know. Good luck.

 

[jangermann]

https://youtu.be/XSeDT2AkAUA

This a video which I recorded in November using my mobile phone, so the quality is horrible bad, but you can see, that until I arrive to highway (around 2:00 in video) it is working fine. After the rapid acceleration it get stuck in 4. gear, so I tried to switch everything: auto-manual, D-S, +/-, but nothing happened until I slow down to the speed which is normal to 4th grade (around 5:00 in the video). After the slow down it is working fine again (until the next full throttle...)

Mine never get stuck in 4. gear. After going from massive acceleration to constant speed, it might keep in 4 gear for a short while, but after that it will shift to 5/6 gear.
I am sure there is a problem with your bike. This it not normal and I have never experienced that.

 

[Fenyvessy]

Mine never get stuck in 4. gear. After going from massive acceleration to constant speed, it might keep in 4 gear for a short while, but after that it will shift to 5/6 gear.
I am sure there is a problem with your bike. This it not normal and I have never experienced that.

The dealer confirmed, that they could reproduce the same behavior in 2nd and 3rd gear too, so it is not depends on the 4th gear. I'm very curious to see what is wrong, what will be the solution...

 

[jangermann]

The dealer confirmed, that they could reproduce the same behavior in 2nd and 3rd gear too, so it is not depends on the 4th gear. I'm very curious to see what is wrong, what will be the solution...

Well it's a computer......

 

[Therapy]

Change some parts eh?
What else?

 

[Fenyvessy]

They finally managed to solve the problem.
The problem was that there was a manual transmission chain sets equipped with the automatic transmission motorcycle.
They replaced the chain wheels to the correct size, and from that point it is working fine again

 

[670cc]

They finally managed to solve the problem.
The problem was that there was a manual transmission chain sets equipped with the automatic transmission motorcycle.
They replaced the chain wheels to the correct size, and from that point it is working fine again

That's good!

That would also be worth noting to someone with a DCT that wants to change the final gearing. It sounds like perhaps the DCT has limitations in how much change it will accept and still function correctly.

 

[dduelin]

That's good!

That would also be worth noting to someone with a DCT that wants to change the final gearing. It sounds like perhaps the DCT has limitations in how much change it will accept and still function correctly.

The gearing mistake makes perfect sense.

The owners manual and service manual both warn against changing tire sizes and buried in the DCT portion of the service manual is a warning not to change tire sizes or gearing because it can cause the ECU to display trouble codes or prevent transmission operation altogether. As you mention the DCT bike is not very tolerant of these changes. The ECU compares data from two transmission sensors that measure gearshaft speeds and vehicle speed to make gearshift decisions. The larger rear sprocket of a manual bike would cause the transmission shafts to turn at higher speeds compared to vehicle speed.

 

[Therapy]

Nice to have an answer.

 

[Fuzzy]

That's good!

That would also be worth noting to someone with a DCT that wants to change the final gearing. It sounds like perhaps the DCT has limitations in how much change it will accept and still function correctly.

Didn't HondaBikePro change his sprockets on his DCT?

 

[Fuzzy]

Here is the post.

For all you dct guys, just dropped front sprocket one tooth to a fifteen, from the stock sixteen. This is a very nice change, d mode works much better with less chain snatch, and lugging, and motor has better pulling power. It is more fun to ride with the sprocket change. Speedo is off 4 mph at 60 mph on the slow side. I will leave it this way, makes me think i am going faster then i really am. Cant tell you the rpm changes, had them on a piece of paper but lost the paper when i opened the trunk at 60, oops. When i install new sprockets and chain will go up four on rear, and back to 16 on the front, and keep the 15 for off road use, in Colorado on some of the high passes would have liked a little more pulling power when loaded. Dale

 

[Therapy]

Here is the post.

Maybe he hasn't held it wide open to see what it is going to do?

 

[dduelin]

Here is the post.

There is obviously some tolerance designed in for tire wear and differences in tire sizing from nominal but there is still the warning in the service manual and the list of associated DTCs associated with transmission sensor anomalies. Perhaps the slightly larger diameter rear tire Dale favors made up enough of the gearing change of the different sprocket so as to not throw a DTC. If the differential shaft speed changes are large enough the DCT shuts down.