Even reasonably smart people do dumb things. Hitting the Minus button on the DCT in Drive

Makingitwork6999

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I have something to share that I discovered by accident. I wished it was the cure for something, but it was actually quite silly.

While accelerating quickly, I bumped the minus button on my DCT at just the right moment. The engine redlined, started backfiring, and the bike roared as it slowed suddenly. No other indication of a problem. I thought the timing of the motor was lost or something. This event lasted about 5 seconds.

Now, I have done this sort of thing in my car, but the transmission usually says. BEEP. No way. And won't let me flip to manual and downshift. My car is very good at stopping you from making dumb shifts.

Apparently, the NC700 DCT allows this.... and it can get a little scary. You can bump a button and bad things will happen.

How did it happen? I was riding with a handle-bar video camera on my bar-end. My hand was slightly out of place, and my hands are a little on the large side. I bumped the minus button when I adjusted my grip while I was on hard throttle. I got the shock of the day. Luckily I was not on the dirt.
 

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Makingitwork6999

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I did. It looks like the bike failed. You can barely hear it misfire.

Not everything on camera is catchable. The videos wont load.
 

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670cc

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The rev limiter has very abrupt engagement on the early models. If the DCT did allow the downshift to redline territory, the rev limiter shuts off the spark. This should not be considered scary. Up shift and move on. No harm done.

It would be interesting to try to duplicate this scenario. It probably takes precise timing to trick the DCT into a downshift when it shouldn’t.
 
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Makingitwork6999

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Well. The way I experienced it, the engine was so unhappy, it was dumping fuel into the pipe and igniting it. The tune was way out of position. So. I would not try to do that again. I thought I broke the bike. I almost blew my home-made silencer out of the tailpipe. So embarrassing.

What it does say is… keep your hand and thumb away from that thing… at least on the 2013 DCT nc700x model when in Drive and accelerating. Automatics are so damn complicated to use!!! :).

Do not put a camera directly on the bar end. Or a bar mirror. Or a hula girl figurine.

To be clear, the bike recovered without issue. And I am going to mount my GoPro on a stalk. further away from my hand and probably from the bar end top.

This was a quick camera mount thingie I did and it worked. But when pulling out onto the roadway from a stop, my hand got out of position. The tight space on the grip pushed my hand too far to the right.

This can also happen in a wooded environment. I would call this, “knocking on the trees” or “clearing the underbrush”.

So. Do not do what “Thunder” does in this case. He is human like everyone else. He has a way of precisely timing some crazy failures. The fact is, if you do something enough times, you shake out the bugs.

Watching a video of yourself screwing up is interesting. You say things you never thought you would say.

There seems to be a vulnerability there in the Auto to Manual mode switch when hitting the minus button.

There are lots of mechanical people and experts who will say, that cannot happen. Then it does happen. Then it happens again. Remember the GM ignition switch thing? It happened on the test track while new cars came off the line very early on. Then it was a shock when it hit cable news.
 

TacomaJD

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I call b.s.....

#1 it didn't redline on downshift and #2 it didn't backfire....unless something is wrong with your bike. Caught you off guard with an unwanted downshift, yes.....but neither of the other 2 things happened.

I have a 2013 NC700X DCT I do trackdays with. It has a Yoshimura exhaust. Stock engine tune. Every time I am on track and going into turns, I am constantly hitting the downshift button at high rpm's until it finally allows me to downshift into the next gear...in no way form or fashion can you downshift a 2013 DCT bike and be at redline in the gear below....the computer will not allow this to happen. And it definitely isn't backfiring, unless something is wrong with your bike, because these mediocre performance engines are tuned so well that there isn't any backfire or popping on deceleration, even with an aftermarket exhaust.

I also have a 2016 NC700X which has a different generation of the DCT and although it seems to allow downshifts at very slightly higher rpms, it still won't downshift to a gear on the redline....again the engineers that designed these bikes knew to safeguard against this and there are conditions that must be met before the computer will allow downshifts.

Here, with the camera mounted behind me, you can hear more of the exhaust than the vids with camera mounted on the front. No backfiring, popping, etc...just smooth deceleration.

Skip to about 2:45 mark, as there was a supermoto bike I was chasing and you can hear his exhaust over mine at times, he finally let me pass at about the 2:45 mark.

 

Makingitwork6999

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Ok. So you are a track person.

Please be nice. Glad you are testing the limits of the minus button. This is why we have forums. … to shake out the bugs.

I have a clone of your exhaust and my tailpipe may be a different diameter than yours. Insert joke here

My tune is not your tune. So maybe something is going on with the tune that made the transmission do what it did.

Maybe the bike took too many bounces. Or I shook the heck out of it before making my turn in traffic.

You push the limits your way. Good for you. I push them my way. Good for me. I am a old racer just like you. But I am not you.

I would not have brought it up if I imagined it. I had the footage. I had to pull over and assess the situation. I could hear myself cursing. The bike needed a moment to do a reset.

I owned enough bikes and made a lot of bad shifts in my life. That one event was quite peculiar. The DCT almost never makes a bad shift. I like it like that.

This forum is for everyone.
 

Makingitwork6999

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I agree that the transmission is very safe. I could not ride at 70mph standing on the pegs with a 20mph headwind if it was not safe. This ramp is over three stories up with a low concrete barrier. People have flown over these barriers and onto the roadway below.

Good to know that you have some experience. Good skills I see in your video. A hallmark of an experienced rider.

Your pipe sounds like a fully open pipe. No quiet pipe attachment. Just a guess.

Mine was like that... and was sluggish. I smeared some epoxy in there until I got the effect I liked.
 

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Makingitwork6999

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Did it again. And I got a roar and a repeated popping. I was clearly at the redline.

And a... whah whah whah whah in a decreasing tone. Sounded like a sport bike rev limiter.

My thumb knuckle keeps brushing the minus button. I think I have it on video during my night ride. I have about 4 hours of video to wade through on that one. It really is not a big deal when it happens. It is really my fault. Long thumbs. It was not dangerous at all. No different than blowing a shift on a manual shifter or a false neutral.

This time I felt myself brush the minus button in Sport mode. I was well into sport mode gear 2. I think I am going to file down the button or add a cushion ring to the grip to force my hand to the left. There is always a solution.

When it happens, you either quickly hit the plus button or pull over and go back to neutral I guess.
 
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