Burgman 400 & 650 new models 2013

[MrGrumpy]

Had one for 3.5 years and it was very smooth with no vibes, only grunty low down torque with plenty of oomph.

I'm no expert but I believe the 270 degree format isn't the issue but rather the overall design and use (or otherwise) of balancer shaft(s) to cancel out unwanted vibes.

Interesting....so it can be done, but it seems that manufacturers seem to be designing vibrations IN to give that 'authentic motorbike feel'....which they can keep IMHO.

[gn2]

[ it seems that manufacturers seem to be designing vibrations IN to give that 'authentic motorbike feel'....which they can keep IMHO.

Indeed, this is exactly what Honda claim to have done and proudly boast about.
"This provides a high-quality ride that transmits a comfortable level of vibration to the rider."
http://world.honda.com/NewMidConcept/chassis/index.html
Well the acceptable level of vibration for this rider's comfort is zero and that is what bike manufacturers should be aiming for.

[Data]

Are you saying specific bits of the NC S/X are a step in the right direction or is it just the mpg generally?

For me the "step" is towards building a modern practical standard roadbike.
As I see it, the big plus points for the NC S/X are the fuel consumption, longer service interval, onboard storage and price.
These are certainly very important but Honda could have done so much better by incorporating existing proven technology to further reduce the maintenance requirements and improve comfort.
Even simple things like tyre size, there is absolutely no need whatsoever for such wide and high speed rating tyres, narrower ones with a speed rating matching the bike's true abilites and intended usage would surely be cheaper when it comes to replacing them.
The things I would like to see in the NC S/X are a smoother running engine with rubber mountings to eliminate vibration, a shaft final drive for reduced maintenance, a centre stand for practicality, a bigger, deeper and comfier seat, bigger storage compartment and hydraulic automatic valve adjustment.
And as for the Integra, let's not even go there, It's just a complete and utter fail.

Got to agree with your sentiments on this gn2. One thing though, Honda did consider a shaft drive, but only very briefly. They calculated that it would on average loose them in the region of 8-11mpg due to the increased pumping losses of the shaft and the increased weight etc etc. This went against the ethos of the bike which is designed to maximise use of fuel and power. It shouldn't be forgotten that chain is still the most efficient power delivery system to the rear wheel as the power transfer doesn't need to be turned through 90 degrees with gears in the engine to deliver it to a shaft, and then turned back another 90 degrees at the rear wheel. That is where most of the losses occur. There was some published information on this from Honda but just can't find it at the mo, I think it was in a trade journal of mine. It used to be that a shaft drive would generally lose around 7 to 12% of total power going to the rear wheel. Modern chains lose between 4-6%. Our rubber bands are probably similar to chains although we've never ever tested a belt on our test installations. The exact figure is dependant on the power setting as the loses are variable with the amount of power being applied. It's not a linear loss across the rev or power output range. I yearn for Hydraulic Valve lifter though! But again, they add weight, increase engine cylinder head size, don't operate so well at high revs (as in motorcycles) over high mileage, and can be unreliable. Many a time I've replace the hydraulic valve lifters on CB750's just because you can hear a massive tapping noise at start up which doesn't go away until you've ridden two or three miles. Caused of course by a valve lifter draining out overnight and not refilling. In a case like that you must replace all the lifters as it's not easily possible to find out which one it is that's causing the problem. And that's expensive. Rubber mounted engines can cause a number of problems with handling and power delivery too. In the new bike we are developing (I'm only concerned with the engine design and dev) we've tried a number of ways to mount the engine. Rubber is definitely not going to be used because of the problem keeping driveline integrity. Ours will however have a shaft. Yes, a surprise I know. But the overall concept of the bike and the type of engine it is having demands we put one in. That's all I can say...otherwise I'll breach my contract. It's been fun up to now though.

[gn2]

Using your figures and simple arithmetic, the net penalty for a shaft is 3-6%, well worth it imo.
I can't help but think that overall the GT550 Kawasaki (which I have ridden and loved) is a superior bike to the NC and that just shouldn't be the case after three decades of "advances".

[Data]

Yes, loved the GT550 but adored the GT750 with that bit of extra power. They went well enough didn't they! Got to say that doing the valve clearances on the GT750 was easy and would be the same on the GT550 also. Neither had hydraulic tappets/valve lifters. But once the tank was off, just lift the cam cover, wire the cam chain, split it and lift the cams out and reshim where required. Didn't actually take very long at all and was just so simple. After it had been done the first time most engines used to go 70-80k miles before needing actual adjustmenet again and checking the gaps was a two minute job at service time. That's why manufacturers have stuck with it so long and it keeps costs down too. It's the same on my Burgman. Valve clearances on the 2007+ models are super easy even thought the cams must be lifted. Anyone with a torque wrench and the know how to use a spanner can do it. But yes, hydraulic would be nice, but probably unreliable in an engine like the Burgman that spends most of it's life above 6k rpm.

[Bluebottle]

Using your figures and simple arithmetic, the net penalty for a shaft is 3-6%

That isn't the total net penalty, there is more to it than simple arithmetic

The shaft itself would lose you 3-6% hp but as Data has described you would also have a bike that no longer does 80mpg and is now below 70mpg which is looking a bit less attractive.

Then it gets worse, because you have lost up to 6% on your hp figure your design may no longer meets its brief, it doesn't match up to the target bhp. To solve that you have to either enlarge the engine to a higher cc or change its design so that it creates more hp. Either way the upshot is that your losses will increase even further and leaves trying to sell an "economy" bike that does 60'odd to the gallon and unimpressive speed for the cc - and that is only after the first "improvement", do we still want to look at the valves etc.?

Do we want the 80mpg bike or the 65mpg bike?

Data's post makes excellent points and illustrates how the design compomise works and that he has genuine experience in the development world.

On the other hand the 270 crank does baffle me. If I'd wanted a V-twin I would have bought a V-twin. Maybe the unmatched pistons would never balance anyway and it was better to be properly out than as bit out due to resonnance or impulse waive benefits at the exhaust valve or something but It seems to be getting toward a gimmick to me.

[gn2]

The GT550 did 65mpg and easily broke the ton which is more than enough.
With four cylinders and a shaft drive.
That was 30 years ago.
It should be possible for Honda to buid a vibration free low maintenance 80mpg shaft driven middleweight right now.
Today.
I want one.
Not interested in opinions why it can't be done, I just want it done and I don't want to hear half arsed excuses.
Moto Guzzi can deliver a 65-75mpg shaft driven 750 so Honda should be able to improve on that?
What I really don't want Mr. Honda is a gimmick motor with gimmick nintendomatic transmission and a bloody chain final drive.
Ah well, just have to stick to scooters.
Which leads to rant number two.
Sort out your UK scooter range please Mr. Honda, can we have a sexy looking 250-350 single cylinder maxi please?

[MrGrumpy]

Got to agree with your sentiments on this gn2. One thing though, Honda did consider a shaft drive, but only very briefly. They calculated that it would on average loose them in the region of 8-11mpg due to the increased pumping losses of the shaft and the increased weight etc etc. This went against the ethos of the bike which is designed to maximise use of fuel and power. It shouldn't be forgotten that chain is still the most efficient power delivery system to the rear wheel as the power transfer doesn't need to be turned through 90 degrees with gears in the engine to deliver it to a shaft, and then turned back another 90 degrees at the rear wheel. That is where most of the losses occur.

This is interesting - thanks. However, I read an interview somewhere with the Honda Integra designer or project leader or someone, who seemed to imply that they chose chain drive because it was cheap!! Which makes more sense to me.
I found some dyno tests on scooter-station - one of the interesting things was whilst the Honda DCT + chain drive combo was efficient (in terms of how much of claimed engine bhp found its way to the wheel), it wasn't apparently that much more than the Tmax mk4 cheapo belt CVT and final belt drive setup, which itself was notably better than the BMW CVT + wet chain system, and a lot better than the Aprilia CVT and crude chain.

There again, we seem to be joining the car world where the only important thing to manufacturers is to claim a high mpg figure! This seems to be the underlying snag with the NC and Integra, everything has been sacrificed for a headline mpg figure. In reality though, would I accept 10mpg less (from a very high figure) for shaft drive??? Well, yes.

[Bluebottle]

...seemed to imply that they chose chain drive because it was cheap!!

that is the other part of the dilemna isn't it

You can get a 50cc bike to do 150 mph on not much fuel - but I wouldn't want to be the one picking up the initial bill

[gn2]

I've been having a think and I am unconvinced that in the real world shaft drive automatically means a significant mpg penalty.
The previously mentioned GT550 and 750 Kawasakis did similar mpg to their chain drive counterparts.
So did the Z1000ST and GS1000G.
A Moto Guzzi Le Mans also did similar mpg to a Ducati Darmah.
An NTV650 gives similar mpg to an SV650.
etc.
Re chain costs, they are only cheap for the manufacturer, not for the owner.