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Need to change sprocket and chain.

tngw1500se

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2015 NC700X
Wife loves the bike but never hardly uses 6th gear. I'd like to gear it down and it's time for a chain anyway. I really only want to change the front sprocket. What the best setup?
 
well from what I have heard 3 teeth up on the rear is the equivalent of 1 tooth down on the front and should be a net gain of maybe 400 rpms at a given speed?
 
While probably not the answer you’re looking for, it seems like as long as first gear pulls strongly from a stop, then not using sixth often is a bonus. One only needs to usually shifts 4 times instead of 5. I would like that more bikes had stock gearing where sixth is only used in certain cases.

If you want to lower the gearing, and you go with one tooth less on the front, the chain will need to wrap a tighter circle as it rounds the front sprocket. I don’t know how that affects chain longevity. If instead you go up two or three teeth on the rear, you’ll probably need a chain that’s two links longer than stock.
 
There really isn't a need to use 6th gear so what's the problem? If it pulls away easily from a dead stop then all is well!
 
I rarely ever go 80, but I’ll have it in 6th by 50. Maybe I’m lugging the engine too much. As long as she is happy with using 1-5, I see no reason to change the sprockets. Now if first is too tall and she wants lower gearing in first than I think a sprocket change is necessary.
 
On my DCT model, with the transmission in "D" to shifts into 6th around 35 mph. If the factory thought that such a low RPM in 6th would hurt the engine, they wouldn't have programmed it that way.

It's mostly a mental thing with us thinking that low RPM in a high gear is "lugging the engine."
 
The engine lugging idea ( mental thing) has a long forum history going back to 2012. The long stroke engine witha lower red line and abrupt rev limiter seems to be part of the history. The NC has a relatively low rpm at 65 MPH cruise.

The weird part is there’s maybe an equal of members that wanted a larger front sprocket to lower the cruise RPM even more.

But there’s a vast majority that are OK with the factory gearing. Also mods and making it your own are part of the game.
 
Many people have been brain-washed into thinking that lugging the engine is a terrible thing sure to cause a connecting rod to fly out of the cases at some point. Maybe it belongs in the scrap heap with the "3000 mile oil/filter change"?
 
Many people have been brain-washed into thinking that lugging the engine is a terrible thing sure to cause a connecting rod to fly out of the cases at some point. Maybe it belongs in the scrap heap with the "3000 mile oil/filter change"?
If studying and practicing mechanical engineering is "brainwashing" then I am one of them.
I don't have to be a specialist in internal combustion engines, but when I see a convincing explanation of the process, I consider it an evident event. Otherwise, studying wouldn't make any sense.
For almost 50 years I have driven mostly vehicles with a manual transmission. Lugging, knocking and pinging are quite common at first with little experience. You learn quite quickly how to avoid it.
I have not come across the claim that lugging the engine can suddenly damage the engine. But it shouldn't be ignored. How this affects the operation of the engine is quite extensively described and I see no reason to discuss it here.
 
Part of the issue is that "lugging" is a poorly defined. Is it WOT at low rpm? How low exactly? Would WOT at 3000 rpm be considered lugging? What about low RPM but light throttle? Or low RPM light throttle but low vacuum and high load? Is idling the engine at high elevation technically lugging? Does there have to be audible detonation for it to be considered lugging? What if the engine, at a given throttle setting, loses speed up a hill? Is it only lugging if that throttle setting is over a given value?

Etc...

The genesis of the term probably comes from single cylinder engines, with light flywheels, mechanical ignition, and crude carburetion - it's definitely possible to ride those engines outside of the ideal load/RPM band and cause detonation, misfires, NVH, inadequate oiling and so on. It's harder to generate those conditions on EFI multi cylinder engines these days, but the term is making a comeback with modern boosted engines where you can create "superknock".
 
If the NC had any remote chance to damage from detonation ( spark knock) they would have used a knock sensor to control the spark curve.
Reality is the it has a relatively low compression ratio of 10.7 compared to other engines with 12.0.
The goal was novice/entry level riders, commuter, high MPG, regular fuel, medium to low power, DCT with high gear ratio and very very low shift points.
 
Honda recommends shifting up to 6th at 60km/h and down to 5th at 45km/h. Of course, this doesn't account for all conditions, such as applying significant power or up/downhill.
The engine was specifically designed to have vibrations. The 270-degree crank and uneven valve timings are intended to produce the "feel" of a V-twin. I'm thinking this is mostly marketing spin and the real reasons were to cut cost and maybe to squeeze more fuel efficiency out of the motor. No matter why it was done, the engine is designed to be "lumpy" when operating normally.
I agree that "lugging" an engine is bad. There are many serious problems that it can cause.
The NC700 engine vibrating and making noise at 1500RPM (45km/h in 6th) is unlikely to fit the definition of "lugging" unless you hammer on the gas, in which case you would downshift before accelerating. And even then, I don't think it would really be "lugging" vice "lumping" as designed.
I think a major part of misunderstanding the concept of "lugging" a motorcycle engine comes from high revving bikes being more common. Note that 45km/h in 6th on my Ninja 300 is over 3100RPM. Trying to operate THAT bike at 1500RPM is very very different from trying to operate my NC700 at 1500RPM. Just like how trying to operate my NC700 at the same RPM as the redline on the Ninja 300 (13,500 I believe) would be very different...

If for no other reason than the owners manual says that 50-ishkm/h in 6th is fine, I'd say it's not going to harm the engine. Recall that manufacturers often impose stricter limitations and additional warnings on things printed in order to prevent legal action. If I consistently operated my NC700 at 50km/h in 6th (1660RPM or so) and it was proven that this was the cause of damage to the engine, I could EASILY go after Honda for the repair bill, as I was operating within their established parameters. Not only that, word would get around that Honda builds a shitty engine since using it as designed destroys it. I doubt they are going to intentionally print information that will cause damage to the machine, especially considering Honda engines in general have a reputation for being reliable.


NONE OF THIS IS TO SAY YOU SHOULDN'T GEAR DOWN/UP THE BIKE AS YOU WANT TO. The bike is yours do do with as you please. If you want to change the gearing so most of your riding is done in 6th instead of 5th, power to you. Depending on how much time you spend in other gears, and how close to the shift point, you might find you actually lose fuel economy overall. From a chain wear perspective, more teeth on the back is preferred to fewer teeth up front, but I can't say how much of an impact it makes. The final ratio is 2.687, so 3 teeth on the back is a little more than 1 tooth on the front as far as end result.
If you're already doing the chain and looking to change the front only, I assume the front sprocket needs replacing but the rear is still serviceable?
 
A long, long time ago, using low RPM at modest speed would have been "lugging the engine," especially with high performance cars and bikes.

We no longer have that situation unless you have a homebrew hot rod of some kind. Most or nearly all the modern Honda
motorcycles and autos are designed to run on Regular gas and they don't seem to really mind running at low RPM.

Circling back to the original post, using or not using the NC's 6th gear is not going to make much difference either way. :)
 
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I would not change the the gearing because first and second gears already have a very short range before the rev limiter. Gearing it down further will require more frequent shifting. Gear it down by adding a much larger rear sprocket and add a cage -- if you want to learn how to do wheelies.
 
On my DCT model, with the transmission in "D" to shifts into 6th around 35 mph. If the factory thought that such a low RPM in 6th would hurt the engine, they wouldn't have programmed it that way.

It's mostly a mental thing with us thinking that low RPM in a high gear is "lugging the engine."
My 2021 with DCT in Standard mode on a flat road with light throttle shifts into 6th at approx 45 mph , with heavy throttle it wont shift into 6th until 70 mph. It seems to like to operate in the 2500-3500 rpm range in std mode. Of course higher rpms 3500-4500 rpms in sport mode. Neither mode or rpm range hurts the motor. It all depends on which range the rider prefers. Both are acceptable.

Lugging, in the traditional sense (chugging, bucking, clunking, stumbling) is not possible on a DCT bike

I used to say that "some guys are revvers and some are luggers" which meant some guys naturally prefer to operate in the upper range of rpms and some guys naturally prefer riding in the lower range of rpms. Personally I fall into the lugger category and will usually run the highest gear possible that a bike will pull cleanly (without actually lugging). Some of my 4 cyl liter bikes would run smoothly at 30 mph in 6th gear and accelerate cleanly from there. My CB 1100 will happily run at 2000 rpms. It will also happily run at 7,000 rpms, although I like to keep it around 3,000 rpms.
 
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If she likes riding the bike and never uses 6th gear, what's the big deal?
I'll ride around in 5th sometimes. Sometimes I'll stroll in 6th. It isn't doing any harm.
 
On my DCT model, with the transmission in "D" to shifts into 6th around 35 mph. If the factory thought that such a low RPM in 6th would hurt the engine, they wouldn't have programmed it that way.

It's mostly a mental thing with us thinking that low RPM in a high gear is "lugging the engine."
I see your point whit the DCT model, but gearbox isn’t the same on Manuel and DCT.
I don’t know the exact difference, but it’s not the same gearing setup on those to engine’s.
If’s Manuel bike going 35 in 6. Gear it for sure is lugging mine does.
If’s 6. Gear is used before 55 miles it’s lugging but over 55 miles it's just okay. But can’t say anything about how DCT model acts like never have tried one.
I might say it’s positive going up 3 tooth on rear sprocket if’s highway isn’t we’re most riding is done. On the Manuel version.
I have studied some utube videos which shows Speedo and gear positions, trying to shift like this on the Manuel bike this goes fore D position on DCT isn’t any pleasure at all, bike is constant lugging and feels jerky all the time.
But this is just what I have experienced whit my 18 model
 
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