Pipe dreams and conjecture.

[Blurredman]

Gents,
But I can't remember having said that 'it's all about the swingarm length and subframe', I think I said "the spine of the frame (which runs below the tank) being longer on the 250".

I had a feeling this might be picked up and pondered my sentence structure. As is the way of the English language, that particular sentence could be construed as either a provocation of wrong info, or a confirmation that it was right.

I said "It's not all about the swingarm length and subframe, as puffs says."

Which I meant to say, 'Puffs was correct in saying that there are also measurement differences from the swingarm spindle forward'.

[nice2day]

Hi puffs...Regarding the KINETIC energy chat. All I was (trying) to say was that a mass ,when, moved has stored energy. The bigger the mass the more kinetic energy for any given speed. Then that same mass also possesses a reluctance to be accelerated, a property called INERTIA.

By adding a heavy weight to the handlebars we load the handlebar and change its response to the small centering force created by the steering geometry: CASTOR effect.

Since the castor effect has a certain "fixed" value, then if we ADD MASS to the object it has to turn, the response must be slower due to the INERTIA. You know that motorcycle steering is incredibly sensitive ...just pull or push on ONE side of the bars a couple of grams pressure and see what the effect has! Be very careful... ..you could end up shooting off the road!

So bottom line is: Add a big mass to your handlebars and the bike will steer differently...that's all.

By the way did you see the similarity of kinetic energy formula to Einstein's Famous equation E=MC²?...basically its saying if something is moving at 90,000,000,000Km every second and then stops instantaneously (vanishes /is destroyed) the energy it contained is released and is massive...I know you knew that but I often consider this fact..... especially when I'm hammering in nails...
Les

[Puffs]

Some bikes have a subframe, and by that they commonly mean part of the frame that is bolted-on; it's the bit that carries the seat & rear mudguard. The (mono-)shock then goes from the swingarm linkage to the spine. The subframe carries nothing (or little) of the bike, and is not structural.

These MZ's have no real subframe in that sense, what you could interpret as subframe is structural, as the shocks attach to it. Anyway, until recently I said nothing about any MZ subframe. But maybe I have my terminology all mixed up...

Yes Les, momentum p = mv. F = dp/dt, so with a constant mass m, F = d(mv)/dt = m dv/dt = ma. See https://en.wikipedia.org/wiki/Momentum.

On e=mc², it reflects the equivalence of mass & energy, with the constant value c² just indicating the proportionality. Not to be confused with kinetic energy ½mv², the origin of which is not so much in the mass, but rather in the velocity thereof.

On further reflection, I suspect your Saxon's steering suffers from a chronic Heisenberg uncertainty infliction. I'd make it lighter & go faster.

[nice2day]

Nice one Puffs...its fun to have a bit of scientific trivia thrown around

Oh yes coming back to Einsteins Theory ...I can only imagine then that everything that exists has a built in property of travelling at the speed of light even though to us it is unmoving?
Its about relativity isn't it.

Les

[Puffs]

Uhh.. No I don't think so Les. Or at least I don't know what a "built in property of travelling at the speed of light" means.

His special relativity builds on earlier work by particularly Hendrik Lorentz and deals with the consequences of the speed of light being equal for all observers. General relativity details the consequences for the space-time continuity & gravity. There is more to be said on this, but it's a bit beyond the scope of an MZ forum.

I'd try the Saxon without that fairing, or with a bigger front tyre - that should make it more stable, both by raising the front a bit, and also by increasing it's angular momentum. What tyre does it have now?

Edit: a programme I saw yesterday made me look up the wheelbase of Marquez' RC213V, it is 143.5cm = 56.5". So indeed 10cm longer than the 251.

[nice2day]

Hi Puffs...It was hard to describe what I meant about the speed of light within matter. I didn't mean it was actually traveling at the speed of light!
However, the immense amount of energy released when matter is destroyed is closely linked to the equation for kinetic energy and that figure is huge because we have the speed of light squared. I am pretty sure if you actually did accelerate any matter to the speed of light and then let it impact into an immoveable solid object (Impossible, I know) the energy released would be similar to that of what is released when matter is lost through fission. I'm talking in very approximate terms but this is a way to visualize the massive amounts of energy fission can provide. Although A heavy mass of uranium/plutonium was used in WW2 bombs the energy created was from the loss of a few grams of matter. This is also why I mentioned hammering in nails...You can't push them into wood, but by releasing the stored kinetic energy from a moving hammer they receive a much greater force and get knocked in.
There is plenty of info out there to agree with what I am saying for example: https://physics.stackexchange.com/quest ... tic-energy

The Saxon tyre is a 2.75" Metzeler M22 I think....but not to worry I will not be riding it for now as I will be riding the preferred MZ ETZ 250.

Thanks again.

Les

[Blurredman]

I will be riding the preferred MZ ETZ 250.

Speaking of which, I would like to see some pictures

[nice2day]

Appreciate your interest Blurredman...All I can find at the moment is a sellers photo of it. I might find more but when the rebuild continues I will take some updated ones. I have to say just looking at this photo spurs me on...I reckon the ETZ 250 looks wonderful...

Les

[Puffs]

Nice!!!... but it would benefit from some clean-up, as you are doing.

OK, in the 301 I'd try a bigger tyre next time. I know the standard is a 2.75"x18", but I think I always used a bigger one, as said currently a 90-100x18", Metzeler Perfect ME77, which would be about a 3.50"x18", which was the previous one too.

[Blurredman]

I think it looks pretty sweet as it is- but I'm well known to abuse my bikes very badly on the appearance front....

[Puffs]

Coming back to the wandering & hesitant steering (viewtopic.php?f=19&t=10745&sid=e6de041668dde1213c024bcde9a7fa13#p52114) you perceived Les, I was looking inside my fork the other day, and I found some washers I had put between the stop and the (standard, original) spring. That extra thickness will give a preload, which will increase the ride hight and alter the steering angle slightly, making it less twitchy.

I looked in the forks as it dived too much on braking. After the forks were rebuild, they had an oil level of 32cm from the bottom = 42cm below the top, which is a more practical indicator. I had also given it 8.35mm preload with those washers:

Preload washers, 8.35mm.jpg (30.98 KiB) Viewed 1381 times

(The one on the spring is steel, the rest are fibre.)
Now I added 2 more washers at each side, raising the preload to 11.5mm. I also added 50cc oil to each side, raising the level to 35cm from the top (=39cm from the bottom). The preload changes the ride height, the higher oil level makes the spring action more progressive.

Adding a few washers might improve how your bike handles. It's an easy thing to try.

The other question would be: in what way are those racing springs different? Was it better with the original springs?

[nice2day]

Thanks for getting back on this issue Puffs. The stiffer springs certainly helped in curing the excessive diving whilst braking, perhaps too much so. Braking in the wet, I noticed that the tyre was more likely to skid as the normal weight transference was not loading the tyre as much and simply pushed the front tyre along in a skid rather than have the bikes weight push down harder on it to secure extra grip. The springs were the Burwins racing ones so might have been fine for crash braking in the dry but for normal winter town riding I would not recommend them. As far as the spacers, there weren't any but I can see what you mean. If money and skill was no object, I would suggest that cutting a V shape out of the frame near the steering head and rewelding to achieve a longer rake by decreasing the steering angle which would provide more stability. Perhaps one day Puffs you might be able to test ride a Saxon Tour 301 and see for yourself that the heavy bar mounted fairing is the cause of the vague steering that leaves one with no confidence. I could remove it but it would look pretty odd I reckon. Thanks again...
Les

[Puffs]

Yes, I would imagine a 'racing' spring to be stiffer, to combat exactly that diving issue.

While the spring constant says nothing about the ride height, changing the ride height by a few mm will have quite a small effect on the steering angle. So indeed, expect no miracles from adding a small spacer. But it's quite a bit easier than re-setting the steering head, and maybe in combination with a bigger tyre it's just enough? At any rate, the handling of my 251 is fine.

Looking at pics of the Saxon Tour 301, I have difficulty believing that little fairing would cause issues. But it might, so why not just take it off for a trial to be certain?

Btw, when I still rode the thing year round, I also had a skidding front in the wet, once or twice, with the standard springs. Taught me the poor-boy's ABS: brake with just 1 finger.
Diving will lower the centre of gravity a bit (well, moves it towards the direction it dives in), but I'm not sure that does much in preventing skidding (the forces @ tyre-road interface remain very similar). But indeed, higher compliance (lower oil viscosity, lower spring constant) may help.