Data wrote:<snip> Higher revs nearly always equals lower mpg in our tests, <snip>

In the same engine yes, but in two different engines one can spin faster while using less fuel than the other one does at lower rpm.

well i'm not going to rule out SYM.seing as i'm on my second GTS(250 and now 300).there awesome...not seen a SyM 400 in the flesh yet..but far better quality than piaggio.IMHO.

gn2 wrote:

StephenC wrote:I have not seen mention of the weight in this thread. And as I believe that acceleration is a function of torque versus weight assisted by gearing, it is quite important, I think.

Aerodynamic drag also plays a part.

Off the line acceleration is going to be about weight.
Aerodynamic drag is going to restrict attainable airspeed significantly, and then it gets complicated.

A shape optimised for one speed is not going to be the best at other speeds so it is always a compromise but broadly speaking: at scooter speedsweight will give the big acceleration gains, drag will give you the big airspeed gains.

gn2 wrote:

Data wrote:<snip> Higher revs nearly always equals lower mpg in our tests, <snip>

In the same engine yes, but in two different engines one can spin faster while using less fuel than the other one does at lower rpm.

Yes gn, sometimes that can be the case. Like you I've been riding for a long time (43 years). I've had every bike you can think of from 50's to 1400's, and some bikes you can't. I'm a motor engineer, ex-tech and now I'm on a motorcycle engine design team. That doesn't by the way, make me any sort of eggspurt, but I understand your enthusiasm. It's clear you like the X10 and the 330cc in particular. It's a nice bike by the look of it and what's not to like! But be careful about believing the hype on it competing with the 400's, the area it's aimed at by Piaggio. If you just want one for what it is then brilliant, but if you really want 400 performance and economy at speed, and carry a load then it's not quite as simple as that. Engine designers know that the more rpms used in any engine the more fuel it will use. That's the benchmark to understand. But fuel economy is a complicated equation that takes in many factors, weight, aerodynamics etc etc, but if you are saying the 330cc X10 could do the same as my 400 Burgman on the NEC run regarding speed, load, and use of fuel they you will be sadly disapointed. It would most likely be near flat out for most of the trip two up to the NEC to match the speeds I was cruising at, and it wouldn't be able to accelerate like my Burgman either with a passenger on. I weigh 13 stone, my passenger was 13.5 stones plus our equipment. The Burgman didn't flintch. It worked hard at times up the hills but it didn't show it too much because the torque was plentiful (36.3nm @ 5800rpm) and set at a good place in the rev range. The torque for road use is actually more important than total bhp. And surprisingly, sustainable torque is not dependant on total bhp either. A smaller bhp figure can be arranged to produce a much higher sustainable torque figure at lower revs than a bigger engine if the designer wishes. But torque (as you prolly know) is a measurement of the engines ability to do work (whether accelerating or climbing hills etc), and in the context we all know it from the brochures, at a specific point in the rev range where it is shown as it's maximum sustainable figure. Once past the max torque revs/figure, it's the bhp that takes over the job of propelling you along as torque drops off. When that happens the engine internal temps start to rise dramtically and efficiency starts to drop, using much much more fuel. All engines only produce the book bhp figure for a very very short time, sometimes just a few seconds due to temperature rises, and sustained large throttle openings, such as on a high speed cruise has the same effect. So an engine producing power and torque at high revs (X10 330cc) will always use a lot of fuel when pushed hard than a similar engine, or bigger engine (Maxsym400/B400) with it's power and torque lower down the scale under similar riding conditions. That's just how the benchmark is. So my B400 will produce 34ps for probably no more than 4-5 seconds and then it will start to drop. At full throttle with maximum load, where it drops to and by how much is dependant on how the engine designer used his skills to fix the 'sustainable' output (this is published as the torque figure). But a power graph normally gives some idea where it is. It's that figure that is published in the brochures. As Stephen says, we really would like a look at the dyno maps to see how each engine performs but from the specs of the Piaggio, it will be a nice engine to ride, but won't punch in the 400 class for higher speeds and load. It's specs say it has to rev to be any match at all, but it will compete nicely with other similar scoots on that front. This seems to match up with what I've read about the 330cc X10 also. It seems to lack mid range punch. Again showing the designer had to put mostly everything at the top of the rev range to get the speed to try to match the 400's. Now the 500cc X10...wow, that's a different matter! Just make your choice carefully and make sure to get a 'good' test ride before buying.

gn2 wrote:

StephenC wrote:I have not seen mention of the weight in this thread. And as I believe that acceleration is a function of torque versus weight assisted by gearing, it is quite important, I think.

Aerodynamic drag also plays a part.

This is also true. but only Peugeot publish their drag figures so that would be down to guesswork for everyone else.

phantom309 wrote:well i'm not going to rule out SYM.seing as i'm on my second GTS(250 and now 300).there awesome...not seen a SyM 400 in the flesh yet..but far better quality than piaggio.IMHO.

From the viewing I had of the Maxsym 400 in February, the quality is superbly 'lush' with good fit and finish. The engine build and quality is beyond reproach. The whole bike felt solid like a Burgman, nothing flimsy about it. And I gotta say this...quality way way beyond the new BMW scooters I have seen! The Maxsym 400 had the bigger wheels too that are an obvious advantage over my Burgman when it comes to ride comfort etc. Seat height was slightly higher than the B400 but nothing onerous. The one I saw did not have abs. In short, I liked it a lot and I won't hesitate to go for the 600i version when I need to change next, subject to the dealer situation continuing to improve. The 600 is coming here anytime now. But, it's unlikely I will need to change just yet having just bought a new 400z abs, which I just love! Can't wait to see the new B400 next year.

Phantom, how do you find the service from your Sym dealer? How many of them are there near you?

Bluebottle wrote:A shape optimised for one speed is not going to be the best at other speeds so it is always a compromise but broadly speaking: at scooter speedsweight will give the big acceleration gains, drag will give you the big airspeed gains.

Drag squares with speed which is why to raise top speed progressively bigger horsepower increases are required.
(I used to have a PPL and instructed in gliders so I understand drag)
What it seems Data and myself agree on and the point I was trying to make is that there is currently not enough hard facts in the public domain to decide whether the X10 with it's 330cc engine will be able to hang with the big 400cc boys at UK legal speeds.
I think it will be close enough, Data provides a good and reasoned argument for why he is sceptical, but as of today it remains to be seen.
As for speed, 70 is the limit so for me as a boring old law abiding phart who is done with touring abroad, anything above 70 is really not too important.

I think we might be surprised by the X10s off the line grunt, dont forget it has a new transmission which supposedly eliminates the drag on dry clutch CVTs. But like Data says, it cantpossibly have the top end grunt. If it was that good, then why have they bothered with the old 500 still?

gn2 wrote:

Bluebottle wrote: As for speed, 70 is the limit so for me as a boring old law abiding phart who is done with touring abroad, anything above 70 is really not too important.

I suppose I'm a bit of a boring bastard, but I very rarely rush on the motorway and generally keep my speeds to 60-65. Sometimes I have a burst upto 80ish, but then gradually slow down to around my normal cruising speed. A 250-350 scoot is perfect for me.

I think we all pretty much agree on most things actually, we all seem to know a bit of stuff and as a collective on this site we eventually seem to get the answers we are looking for. That's what's so good about this site. I think the X10 will be a revelation too. Won't be long before someone puts it on the dyno for sure and then roadtest it. Then we will have an even better idea of what it's like. As things stand and as far as I can see there won't be anything much to touch it in it's class, and I expect fuel consumption will be a class leader if ridden sensibley.

Did anyone see it at the NEC show last year, or was it not out at the time? I went to the show and remember the BMW's but I don't remember the X10, but I was a bit preoccupied with other stuff at the time relating to work and engines and was busy getting info on the competition.