Burgman 400 & 650 new models 2013

[Data]

I remember the Zephyr Z750 Kawasaki. It was the GT750 without a shaft and it did significantly more mpg's from what i remember. I used one on several occassions but never checked the fuel economy and couldn't tell you for sure what the figures were. Our network manager had the GT750, piled it up and bought the Z750 version afterwards. I'm only going by what he used to say about how much better is was on fuel. We were all very keen bikers back then and took note of anything and everything relating to our bikes. That was way back in '93'. But the only way you will be able to make a fair test is to compare like for like. We have done that on our new engine and tranny (only on the bench) and it was a very noticeable difference. But not huge in mpg terms. As a percentage it was an average difference over the test cycle of 8% point something or other (we did these tests over 18 months ago!), on that engine and transmission and for that test cycle that we adopted compared to the chain tests we did with the very same engine and modified tranny. The tests were designed to work out the losses and later we tested the engine and transmissions to destruction. On the bench the differences were significantly higher at times and of course much lower at other times, so depending what speed and type of riding you are doing your mpg could be quite abit down or hardly any different to a chain in some riding conditions. But to be clear, this means in real practical terms the bike will overall suffer quite a bit compared to a chain driven version under normal riding conditions. There is something else too. The engine were are developing is a mulitcyclinder diesel engine, the likes of which no one will have seen before. It's revolutionary. Can't say anymore. A petrol engine would have suffered much more.

But you are no doubt right about your ciggy packet comparisons for those other bikes you mention. However, in real test conditions if you compared them to an identical chain driven version there would be a noticeable difference for lots of reasons and it would be variable depending on the type of riding being carried out by each rider. But you are right gn. A shaft doesn't necessarily mean bad economy if the engine and tranny are designed right, but it does mean more pumping losses than a chain, but maybe it doesn't matter too much if the weight can be kept down and efficiency maintained as best it can.

[gn2]

The Zephyr 750 came along ten years after the GT.
My memory of the Kawasaki GTs is that the mpg was almost identical to the twinshock Z and GPz.

CVT and belt has an even bigger mpg penalty.
Chain drive manual scooter anyone?
No, thought not.

[MrGrumpy]

Since we are getting technical.....is a chain in oil bath (eg TMax) as efficient as a 'naked' chain??

[gn2]

Efficiency isn't really the problem though.
Simplicity in use, reduced maintenance and longevity is where it's at.
An oil bathed chain is a complex solution for a problem which can and should simply be eliminated.
My fag packet says that if the chain is immersed in oil there will be increased drag on the chain making it potentially less efficient than a well maintained one in fresh air.
But the bathed one won't rust and wear should be much reduced.

[Data]

I would disagree there gn. An oil bathed chain is not a complex solution. It's the most practical in most cases, and the least complex. But it's lightweight and efficient. The chain doesn't need to be oil bathed though, and few have ever been oil bathed, but just enclosed. Oil bathing is unnecessary and a complete waste of time in this day and age. Enclosure though that's different. We found toothed belts to be the most efficient with minimal losses. The main problem we had was longevity. Our engine is very powerful and has so much torque it shredded them very early at the testing stage (it has 100% torque available at 1350rpm!). Initially, we were only a very small concern and dev costs were a big consideration and having a special belt made to take the strain was enormous in terms of cost as it would have been low volume. I don't know about the efficiency of the cvt though. Anyone done any research on it apart from the manufacturers. It must be pretty good as my Burgman is amazingly economical however I ride it.

[gn2]

I appreciate the difference between an oil bath and an enclosure.
The enclosure is less complex than a bath, but neither is as anywhere near as good a soution as a shaft.
CVT frictional losses are very well documented, if you have a poke around you should find plenty of info.
I think the Burger's economy is due to good mechanical and aerodynamic design.
For me the ideal motorbike would probably be a modernised version of the BMW K75.
An 80mpg 120 triple with shaft drive and 10,000 mile service intervals, now that would be something.

[Bluebottle]

I don't know about the efficiency of the cvt though. Anyone done any research on it apart from the manufacturers.....

If I can dig it up I've got some independent figures comparing direct drive electric to CVT losses.
Comparing with your work gets a bit apples and oranges though - it would need to be losses in the whole drive train and gearbox not just the shaft if you are comparing with a CVT.

As I see it, the big plus points for the NC S/X are the fuel consumption....and price.

Efficiency isn't really the problem though.

I can't follow this at all:
Efficiency is a big plus but efficiency doesn't matter?
Price is a big plus but add pricey components?

what are you going to do about the handling problems of a shaft drive on a lightweight bike? More weight and expense?

[gn2]

I'll try to explain.

Efficiency:
Do I want good fuel consumption? Yes
Do I want chain drive? No
Am I prepared to accept a small mpg penalty (if indeed there is one) for the convenience of shaft drive? Yes

Expensive transmission componentry:
Would I pay more to have shaft drive? Yes so long as it wasn't excessive
Would I pay more for DCT? Absolutely no way

As for handling problems of shaft drive, well I'm sorry but this is just an urban myth.
Shaft drive bikes handle perfectly well for road use, just follow any Police motorcyclist on a boxer twin up a bendy road for confirmation of same.
Interested to know what lightweight bike you are talking about, the NC700S is heavier than the four cylinder Hornet.
Back to the Kawasaki GT550 and my fag packet, it was only a few kilos more than the Z550 so weight penalty not really an issue.

[Bluebottle]

As for handling problems of shaft drive, well I'm sorry but this is just an urban myth.
Shaft drive bikes handle perfectly well for road use, just follow any Police motorcyclist on a boxer twin up a bendy road for confirmation of same

Urban myth?
If this copper is on a BMW he's got a paralever to reduce shaft effect problems, or is he on a Yamaha with its telelever?
If its an urban myth, how come it needs these extra features to prevent it happening?

Try riding a vintage shaft drive without these features and your urban myth might just plant you on your face - that makes it real enough for me

[gn2]

I was thinking of a pre paralever one, maybe I'm showing my age.
As for riding older shaft drive bikes I have ridden a GT550, Yamaha XS750, Suzuki GS850, BMW K100RS and a Kawasaki Z1300(DFi) extensively both in the UK and on the continent.
Is that enough of a try?
All handled perfectly adequately, some better than others but none presented any real problems attributable to shaft final drive.
Anyway you seem to have shot down your own argument, a modern bike with shaft drive wouldn't handle like a "vintage" one, unless some committee of clots decided to engineer in some bad handling as a "character" feature to match the shitey vibrating engine.