Changing gearing on a DCT model

[Guest Marcusrm]

Has anyone tried changing the overall gearing on a DCT model?
I am interested in raising the gearing for more relaxed cruising & better fuel economy.
I have done this on my previous bikes, with no noticeable loss of performance.

The problem is that both the user & workshop manual warn against changing sprockets, suggesting that the DCT control
system will not work correctly.

I can't see why this should be so, but then I am not familiar with the software algorithms in the DCT contoller.

My views on gearing go against popular opinion. In my judgement, the only reason to lower the gearing
is that you regularly use full throttle up to peak RPM and the bike doesn't accelerate fast enough.
If you don't use full throttle & peak RPM, then you can accelerate harder by opening the throttle more
& revving higher.

An observation on gearing...
The NC700 is reckoned to have half of a Honda Jazz engine, albeit with a few tweaks.
My wife's Jazz revs at 2000RPM at 60MPH, the NC revs at 3000.

 

Sorry about the blooper in the heading but I can't change it!

Edited April 22, 2013 by Marcusrm

[Guest Phil XD]

Speed sensor is not aware of changed sprocket ratio, thus assuming a different speed than there is in real. Which means, auto gearing will no longer match reality. You will get mistaken gear ups, most likely way too early. Current speed is a major DCT input parameter, I guess.

 

BTW I have done things like that myself with other bikes, but I would not do it with an NC, no matter whether auto or not. I do not believe there is any positive impact for this kind of bike, since 6th gear is fairly long already.

On the other hand, first gear should be kept as is, IMHO, since it already is quite long. Riding uphill slowly with stop&go will reveal this quickly. This needs quite some clutch slipping. So, if you increase secondary transmission ratio, this might get nasty very soon.

[bikerbampi 542]

Whatever he said, I think. 

[edgey999 115]

I have to say that having owned 2 NC700X's (1 manual and 1 DCT) I have never felt the gearing was a problem. I dont think I would want to mess with it on DCT in all fairness and having pottered around on it for the last 2 days I dont think I need to.

 

Just my view

[Guest motorboy]

Honda  has a paper out on that subject and they say NO don't do it messes with the front and rear wheel sensors makes it shift weird if I can find it I think I have it somewhere....

[michael 324]

Marcus, I too had considered the affects of a gear change. A popular gear change on my VFR was to add one tooth to the countershaft sprocket. I'm wondering if I might consider the same thing for the NC to relax the rpm at road speeds....perhaps at next chain replacement.

[Guest Emil]

It is possible and at least one rider on the German forum has done it, complete with Speedoheale. Top speed is slightly higher due to 6th being 6% shorter, and the gearbox switches to 6th earlier - below 60 km/h instead of slightly above as before. This might actually give you better fuel economy when riding in town.

There are some pitfalls involved because the control unit must still get the "uncorrected" speed signal, otherwise there will be a fault condition.

If you really need this info I can translate it.

[Guest Stu]

It is possible and at least one rider on the German forum has done it, complete with Speedoheale. Top speed is slightly higher due to 6th being 6% shorter, and the gearbox switches to 6th earlier - below 60 km/h instead of slightly above as before. This might actually give you better fuel economy when riding in town.

There are some pitfalls involved because the control unit must still get the "uncorrected" speed signal, otherwise there will be a fault condition.

If you really need this info I can translate it.

Just for clarity, did he get a higher top speed from going up on the front sprocket (that is more teeth)? or down?

[Guest Emil]

One less, 15 teeth. Top speed is slightly improved because the 6th gear (that will never hit the limiter) is shorter then. Only by a few km/h though.

[Guest Stu]

One less, 15 teeth. Top speed is slightly improved because the 6th gear (that will never hit the limiter) is shorter then. Only by a few km/h though.

Ahh I understand, that makes sense.

I wonder how that would make the drivablity of a manual? Better acceleration or just running out of revs all the time in the lower gears?

Sounds good for a DCT, although claims of better MPG might be a bit hopeful?

[deecat 318]

I have been running my manual 700x with one tooth less and for me I would not go back to standard gearing.

 

The bike is better of the line and around town it feels a lot less of a struggle in top gear.

 

I have been having some runs out with my son on his new to him 600 hornet and taking it steady as he has been of the road for some time so we have kept mainly to the speed limits and my bike has been averaging 78mpg with the lower gearing

which I am happy with.

[Guest Emil]

Sounds good for a DCT, although claims of better MPG might be a bit hopeful?

Outside town range will be reduced, but in town it could well be higher. Most people here drive about 60 km/h (speedo value), about 57 for real. That is because that kind of speeding (above the allowed 50 km/h) will only cost you €15 in Germany. Therefore I often have to stay in 5th gear in town, while with the shorter 6th gear it could be engaged much more often.

[wozza 967]

Well towns in the UK are so overcrowded you can forget 6th gear in town no matter how low the gearing. Surely on a DCT getting into 6th gear at around 40mph is pretty good anyway to my way of thinking.

Edited April 25, 2013 by wozza