Lugging below 2.5k revs

[Smallville]

Once you get to a certain size piston you have no choice unless you want your fillings to vibrate out of your mouth. 650cc pistons is about the upper limit for a single cylinder design wise. I read an engineering article about it years ago but don't remember the specifics well enough to repeat. With the increased piston size in the 750 they were probably forced to go with the dual counter-balancers.

You know the 700 and 750 are twin cylinder right?

 

[johnakay]

well here's my 2 cents on what I think regardless whether its a 700 or 750.
the 'D' mode is ideal for motor ways or longer straight roads than normal..
the 'S' mode is ideal for town etc or twisty roads where on the normal bike you would go up 'n' down the gears.
yesterday we did a 178 miles trip.
on short twisty roads I kept it in the 'S' mode but soon as I see a good straight 1/2 mile or more I put it in 'D' mode.
and still return a good mpg,don't forget I ride two up all the time rarely do I ride alone.
when we got home there was two and a half bars left on the clock.
the reason I said 21/2 is when I move the bike reversing into the garage using my feet it shows 3 bars then 2 etc.
the 'D' mode is designed to give better mpg but not at lugging speed.

 

[ste7ios]

Exactly! I use 'D' mode most of the time, and 'S' only in windy roads because I need engine braking to retain speed and more controllable acceleration in turns for weight transfer.

 

[670cc]

My engine lugs badly below 2.5k revs and in every gear, my bike's a DCT and in D mode it's very obvious and consistent, it feels almost like a misfire that travels through the bars and I wonder if this is part of the vibration problem that these bikes are known for. When the bike's in S mode it's very smooth.

Reyno, other posts indicate you have modified your bike's intake and exhaust. Don't be offended, but the obvious question is, we're your lugging symptoms present before your mods?

 

[Todd L.]

You know the 700 and 750 are twin cylinder right?

I edited so you can understand.

 

[scrumpymike]

well here's my 2 cents on what I think regardless whether its a 700 or 750.
the 'D' mode is ideal for motor ways or longer roads than normal..
the 'S' mode is ideal for town etc or twisty roads where on the normal bike you would go up 'n' down the gears.
yesterday we did a 178 miles trip.
on short twisty roads I kept it in the 'S' mode but soon as I see a good straight 1/2 mile or more I put it in 'D' mode.
and still return a good mpg,don't forget I ride two up all the time rarely do I ride alone.
when we got home there was two and a half bars left on the clock.
the reason I said 21/2 is when I move the bike reversing into the garage using my feet it shows 3 bars then 2 etc.
the 'D' mode is designed to give better mpg but not at lugging speed.

That's a really good way to do it and just what I did at first, but then I got obsessed with playing tunes on the darn thing - it's so much fun!!

 

[Skeleton]

Personally, I allow my bike to work hard starting at 2000 rpm. Yes, I can feel the elevated effort (torque pulsing) of the engine at that low rpm, but I know the available torque is still high (80% of maximum). I suspect that ill effects would arise only at much lower engine speed, say 1500 rpm.

Enclosed is the torque and power curves for the Honda NC700 engine (sourced from MCN in 2012).

The torque curve is very flat from 2500 to 6200 rpm. That means to me that the effort-per-speed (HP/rpm) is the same throughout the range, regardless of vehicle speed. The bike should not strain any different over that entire rpm range.

Even at 2000 rpm, the torque (35 ft*lb) is still significantly high (80%) in proportion to the maximum (44 ft*lb). Strain on the engine should be no more than 25% higher (1 - 1/0.80) than nominal.

But at 1500 rpm, the torque (25 ft*lb) is significant low (57%) in proportion to the maximum (44 ft*lb). Strain on the engine should be very high, at 75% higher (1 - 1/0.57) than nominal.

When a bike is coasting along at a steady speed (or slowly accelerating), there is less power delivered to the rear wheel than the engine speed would suggest. While engine speed is up, the rate of consumed fuel (and thus work done) is low. The forces in the cush drive on the rear wheel are small, because only little force is required to keep the wheel turning at constant rotational speed.

When a bike is accelerating fully, full power is demanded of the engine. Rate of fuel consumption increases to maximum. The forces in the cush drive on the rear wheel are large, because the rear wheel is resisting the acceleration encouraged by the engine. With the rubber blocks in the cush drive fully compressed, the high torque pulses of the engine get transmitted fully to the rear wheel, and this is what the rider feels - lugging of the engine. It is only here that the rider experiences the full torque that the engine is capable of. Don't be affraid of the symptoms of the torque (torque pulses - lugging).

Now, full torque under very low engine speed (1500 rpm) is a different matter. Again, lugging is felt by the rider as it is very pronounced. But something else is happening here (low vehicle speed) which have undesireable consequences. The inertia of the bike imparts a reversing of the torque under slow vehicle speed, when the engine is between stroke cycles. The bike is seen to lurch forward in repeated quick pulses. Note, the cush drive is not a true damper, because it is made of elastic rubber and not viscous material. A cush drive is actually a spring - but that alone is good enough to reduce the high pulsing loads of an engine onto its drive train. But low speed, high torque loading can over-load the rubber springs of the cush drive. In fact, there is even a potential for harmful resonance to arise (which is characteristic of all spring systems). Ouch!

 

[jesse096]

My manual model does the same, the engine RPM is too low to give the smooth operation you're used to.

-Jesse

 

[L.B.S.]

Once you get to a certain size piston you have no choice unless you want your fillings to vibrate out of your mouth. An example is 650cc pistons is about the upper limit for a single cylinder design wise. I read an engineering article about it years ago but don't remember the specifics well enough to repeat. With the increased piston size in the 750 and being a twin cylinder they were probably forced to go with the dual counter-balancers.

Honda Worldwide | Global 700cc Engine for Next-Generation | Introduction

 

[kpinvt]

Honda Worldwide | Global 700cc Engine for Next-Generation | Introduction

From the last paragraph on the second page of the article linked above:

"However, in order to achieve the emotional comfort of a slightly rough throb and satisfy the development concept of a "ride to suit mature tastes," the team made a deliberate decision keep the vibration and go with the uniaxial primary balancer instead of its vibration-eliminating biaxial cousin."

Thanks for posting the link, I don't think I've seen it before. Right under my nose is the best place to hide things from me.

 

[Reyno]

To update the thread and reply to you all I'd like to tell you that my bike was lugging before my mods but possibly slightly less, I only rode it twice before the mods and only used it in D mode once.

Two days ago I refitted my Honda air filter making my bike standard apart from the de-cat pipe and the lugging seemed the same.

Today I refitted the DNA air filter and the lugging was worse than I've ever felt it, my dash pod was visibly shaking, something it certainly didn't do before. I've only done 30 miles with the DNA air filter back in so I'm hoping this will change.

I took some 0-60 videos with a 60fps camera yesterday (since I can't get on a rolling road because of the DCT) and I was getting consistent times between 4.80 - 5.0 from 0-60mph, this was with the Honda air filter, de-cat pipe and Honda end can, I'll record some more runs with the DNA air filter once I feel the bike's adapted itself to the filter, after that I'll fit a Scorpion end can for more runs and see if there's any change to the lugging.

I'm starting to suspect the 750 doesn't respond well to engine mods and I might have been better off getting a 700 as I've read many reports of considerable gains after fitting only an air filter, as mentioned I went back to the standard filter two days ago and the bike felt no different in S mode and lugged more in D. I'm hoping once I change the end can me and the bike will be more happy, I can live with the lugging in D mode but I just want to lose as much of the bogging effect from take off as possible.

 

[L.B.S.]

To update the thread and reply to you all I'd like to tell you that my bike was lugging before my mods but possibly slightly less, I only rode it twice before the mods and only used it in D mode once.

Two days ago I refitted my Honda air filter making my bike standard apart from the de-cat pipe and the lugging seemed the same.

Today I refitted the DNA air filter and the lugging was worse than I've ever felt it, my dash pod was visibly shaking, something it certainly didn't do before. I've only done 30 miles with the DNA air filter back in so I'm hoping this will change.

I took some 0-60 videos with a 60fps camera yesterday (since I can't get on a rolling road because of the DCT) and I was getting consistent times between 4.80 - 5.0 from 0-60mph, this was with the Honda air filter, de-cat pipe and Honda end can, I'll record some more runs with the DNA air filter once I feel the bike's adapted itself to the filter, after that I'll fit a Scorpion end can for more runs and see if there's any change to the lugging.

I'm starting to suspect the 750 doesn't respond well to engine mods and I might have been better off getting a 700 as I've read many reports of considerable gains after fitting only an air filter, as mentioned I went back to the standard filter two days ago and the bike felt no different in S mode and lugged more in D. I'm hoping once I change the end can me and the bike will be more happy, I can live with the lugging in D mode but I just want to lose as much of the bogging effect from take off as possible.

Honda also geared the 750's a bit taller, any thoughts of experimenting with a new sprocket tooth count combo to get it out of the shudder mode it's doing now? That might be a "band aid" fix so to speak, but it's a relatively cheap way to alter the bike's lugging at lower (subjective) speed/RPM

 

[johnakay]

you shouldn't do any mods while the bike is under warranty.
if it goes pear shape and they find that you have modded it ..you will find that you will not be covered under the warranty.
also you'll not be covered insurance wise either unless you have informed them.
if the police pull you over and notice that you have mods(exhaust) on your bike ,they will check your insurance and you'll know what happened next??

 

[Reyno]

Honda also geared the 750's a bit taller, any thoughts of experimenting with a new sprocket tooth count combo to get it out of the shudder mode it's doing now? That might be a "band aid" fix so to speak, but it's a relatively cheap way to alter the bike's lugging at lower (subjective) speed/RPM

I did start a thread about this but it didn't conclude anything, I was told the gearing may confuse the DCT, I'll try it after I've changed the end can.

you shouldn't do any mods while the bike is under warranty.
if it goes pear shape and they find that you have modded it ..you will find that you will not be covered under the warranty.
also you'll not be covered insurance wise either unless you have informed them.
if the police pull you over and notice that you have mods(exhaust) on your bike ,they will check your insurance and you'll know what happened next??

I know very well how manufacturers and dealers try to distance themselves from problems. It was the Honda dealer at my first service who I asked if a de-cat would affect the warranty and they said no, I further asked if an FI controller would affect the warranty and again they said no and explained that those mods would not cause any problems and if my engine did have any problems it would be an issue that started from the factory, they also explained that if I changed or reworked the internal parts then this would affect the warranty and if for example if I broke my exhaust or any other part whilst changing it I would be responsible.
I don't trust dealers at all but what he said makes sense, besides if I did have any problems I would convert my bike back to stock just to be safe, it would take less than an hour.

As for insurance I've never had any problems telling them what they need to know and more, I've always found bike insurance to be cheap and mods to have little effect on the cost. I'm not sure what police force you're used to but I've never heard of anybody having their exhaust insurance status rang through by the police, I've heard of plenty of defect notices and for noisy exhausts but I'm quite sure the usual undeclared mods are only of interest to the insurance company and their assessors.

It may seem unusual trying to get a little extra out of what is already a great bike with acceptable power but that's part of the fun for me, I'm having an interesting and enjoyable time finding out what works and what doesn't and if I find that extra power it's going to be very satisfying, also I think my experience will be of help to anybody modifying or thinking of modifying a 750 or 700 now or in the future, I thought that's what forums were about.

 

[johnakay]

believe it or not one guy here so I'm told got done exactly like that modifying the pipes.
must have had bad insurance.
I to never had problems but then again I hardly do any mods other than adding stickers.racks,chain oiler etc.
as for warranties well thats your risk.

 

[mgmirabelli]

Just out of curiosity, what is your impression of your NCX versus your Sportster, engine feel-wise?

It's interesting, the NC and the Sportster 883 are both 50 hp, 45 ft.lb torque bikes but feel completely different. The Harley has a ton of low end torque so it is much faster than the NC from a stop. However at 40-45 mph the Harley is out of torque and the NC has plenty to spare. I just enjoy riding. I love my Harley and my NC. Two totally different experiences. We have a cool hobby!

 

[Wild ill]

What Fuzzy said.....What is lugging?...I have always thought it happens when you give the motor more fuel than is can use.....These motors are low RPM and VERY HIGH TORQUE.....They are maid that way on purpose......to get fuel economy.... 1 Reduce weight 2 slow the motor down.....

 

[Old Can Ride]

There is no motorcycle that puts out the pure low end torque of a big thumper. These are two great examples.

BSA Victor


Yamaha WR400


However, KING KONG, is required in kick starting either of these bikes.