DCT Gearing Change?

Nessuno said:

Can you change the final drive sprokets on DCT bikes or is it going to throw a bunch of error codes?

Can you get around this?

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I had a look over on the NC700 forum to see if that had come up. It did come up - very directly. http://nc700-forum.com/forum/nc700-technical/1418-sprocket-change.html?highlight=sprocket+change And in usual forum fashion everyone answered a different question - none answered the one posed. Bottom line seems to be that no one has tried.

Haven't changed sprockets on my NC700 DCT either, but can't think of a reason it would do much more than affect speedometer readings and acceleration rates. But that's just a guess. ECU's are called black boxes for a reason. Who knows what motivates them?

JustPlainBill0 said:

I had a look over on the NC700 forum to see if that had come up. It did come up - very directly. http://nc700-forum.com/forum/nc700-technical/1418-sprocket-change.html?highlight=sprocket+change And in usual forum fashion everyone answered a different question - none answered the one posed. Bottom line seems to be that no one has tried.

Haven't changed sprockets on my NC700 DCT either, but can't think of a reason it would do much more than affect speedometer readings and acceleration rates. But that's just a guess. ECU's are called black boxes for a reason. Who knows what motivates them?

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Thanks for the response Bill. My thinking was that because the bike uses so many variables to determine TC levels, incline/decline and what nots, it COULD possibly screw with the algorithms used for determining those parameters.

Had a aprilia tuono APRC before with TC and even after a tyre change you had to calibrated the system again. It took 10 sec to do the " learning in" procedure.

Nessuno said:

Thanks for the response Bill. My thinking was that because the bike uses so many variables to determine TC levels, incline/decline and what nots, it COULD possibly screw with the algorithms used for determining those parameters.

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Nessuno, I'm thinking the tendency for riders to change sprocket tooth counts is so much a part of motorcycle culture, it's hard to imagine them either ignoring it or messing with it. Anyway, since they quit using mechanical speedometers, speed is usually calculated from the engaged gear and rotation of the countershaft. Lacking sensors for the sprockets, changes external to the engine itself, shouldn't be detectable by the ECU.

Oh, and I just remembered that when you change sprocket sizes, it will affect odometer as well as speedometer readings. It makes performing regular maintenance based on miles traveled a little problematic.

speed and odo , at least honda VFR1200, is done by the ABS sensor at rear wheel. Means that they measure the wheel rotation. So changing the sprocket doen't influence speed and odo meter.
Fuel maps are calculated bij engaged gear engine RPM, speed,barometric pressure and airinlet tempeture by ECU.

Bartho said:

speed and odo , at least honda VFR1200, is done by the ABS sensor at rear wheel. Means that they measure the wheel rotation. So changing the sprocket doen't influence speed and odo meter.
Fuel maps are calculated bij engaged gear engine RPM, speed,barometric pressure and airinlet tempeture by ECU.

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You are quite right Bartho - I forgot about the speed sensors needed by ABS systems to operate, and of course the AT DCT has those sensors. So Nessuno, that makes a pretty convincing case for sprocket changes not affecting the ECU and wont cause it throw error codes. One minor item that doesn't affect Bartho's point; the VFR1200 has a shaftdrive (cardan) so it doesn't use sprockets or chains. :smile2:

I've been reading the DCT uses 3 speed sensors in the crankcase to measure shaft speeds. Also from what I've been reading the owners manual for the 700's with DCT warns against changing tire sizes or final drives as it could throw transmission trouble codes.

ricecrispy said:

I've been reading the DCT uses 3 speed sensors in the crankcase to measure shaft speeds. Also from what I've been reading the owners manual for the 700's with DCT warns against changing tire sizes or final drives as it could throw transmission trouble codes.

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I looked high and low and could find no such warning in the owners manual for my 2013 NC700. Which is curious because there are warnings for every other possible danger.

JustPlainBill0 said:

You are quite right Bartho - I forgot about the speed sensors needed by ABS systems to operate, and of course the AT DCT has those sensors. So Nessuno, that makes a pretty convincing case for sprocket changes not affecting the ECU and wont cause it throw error codes. One minor item that doesn't affect Bartho's point; the VFR1200 has a shaftdrive (cardan) so it doesn't use sprockets or chains. :smile2:

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Finally got out my NC700 Service Manual and found that the speedo/odometer use a VS (vehicle speed?) sensor positioned on top of the transmission case -- probably over the output shaft. Evidently, on the NC700, the wheel speed ABS sensors are used by the ABS to compare front and rear wheel speed, not by the speedometer to determine vehicle speed. Maybe on the VFR too?

As for the AT, better wait for a service manual for that.

The Vfr1200 is complete other system because it is a Ride By Wire bike. So the ECU controlles the throttle. All input sensors going to the Ecu . Because the AT is normal cable throttle and the NC to the system works not the same way. Because it'S cable throttle there is no Cruize control.

Bartho said:

The Vfr1200 is complete other system because it is a Ride By Wire bike. So the ECU controlles the throttle. All input sensors going to the Ecu . Because the AT is normal cable throttle and the NC to the system works not the same way. Because it'S cable throttle there is no Cruize control.

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That makes sense. But I notice that even with ride by wire, cruise control units for the VFR1200 (F or DCT) like MCCruise or Rostra use a servo motor to control the throttle opening instead of the VFR's ECU. Just have to wonder if Honda motorcycle and Honda automobile engineer ever talk with one another. Honda cars have had factory electronic cruise control forever but the Goldwing seems to be the only Honda motorcycle with a factory CC.

ricecrispy said:

I've been reading the DCT uses 3 speed sensors in the crankcase to measure shaft speeds. Also from what I've been reading the owners manual for the 700's with DCT warns against changing tire sizes or final drives as it could throw transmission trouble codes.

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I know of one who discovered his new DCT bike had the wrong (manual)chain installed by the dealer. The only way he found out was because the DCT would not work as intended.

Warning or no, the above should be reason enough to let alone what we don't understand. It's an expensive bike to experiment with, unless you do like wasting currency.
What we do know is that DCT equipped models will shift according pre-mapped algorithms that take into account shaft, vehicle speed and throttle input to shift up or down; try and fool the computer with one of these, the ECM will not be happy.

If you know what you're doing and have to change sprockets, buy the standard version or the manual model.