500cc

<div class='quotetop'>QUOTE(waterfire @ Nov 19 2007, 12:26 PM) [snapback]101401[/snapback]<div class='quotemain'>
Hello to everyone.

Can someone explain why can´t we go back to the 500cc?


But why would you want to??

<div class='quotetop'>QUOTE(waterfire @ Nov 19 2007, 02:09 AM) [snapback]101408[/snapback]<div class='quotemain'>
Ok
So why did they change to 990cc and then 800cc???


That was for safety reasons the bikes where getting too fast.

Two Strokes are too expensive so going back to 500 would be a problem, they want to get rid of 250s for the same reason.

<div class='quotetop'>QUOTE(waterfire @ Nov 18 2007, 10:05 PM) [snapback]101413[/snapback]<div class='quotemain'>
Ok I think I haven´t made myself clear. What I would like to know is why can´t we have 500cc with 4-strokes. The same for 125cc and 250cc.
Is it not possible with the present tech to maintain the same perfomance, or close?


Not so much. A 2 stroke engine of say 500cc will make roughly the same power as a 4 stroke of 1000cc, because they make power every 2 strokes (hence the name), while 4 strokes make power every 4 strokes. This is why you see 4 stroke 250cc dirt bikes replacing 125cc 2 stroke bikes, as another example.

<div class='quotetop'>QUOTE(waterfire @ Nov 18 2007, 10:05 PM) [snapback]101413[/snapback]<div class='quotemain'>
Ok I think I haven´t made myself clear. What I would like to know is why can´t we have 500cc with 4-strokes. The same for 125cc and 250cc.
Is it not possible with the present tech to maintain the same perfomance, or close?


Wow, you guys are gettin' me con-fused!! the change from 500cc 2-stroke to 990cc 4stroke was two-part: 1) the 500s had reached a point at which there was no room for further technological development, and 2) 4-stroke near-liter bikes were more in line with what the world was/is buying from the manufacturers. It was decided, then, that techno-trickle down would make more sense if you started with something a bit more closely-related to production bikes. Keep in mind, all of these MotoGP rides are strictly prototype, hand-made one-offs. They are much more advanced than what we're able to buy The major drawback for the racing teams is that 4-stroke bikes have more moving parts, and are a wee-bit more complex to design than the 2-strokes. This has driven the cost of running a race team sky-high, and that is certainly not a good thing when proper sponsorship is at a premium !!

For the same given displacement, a 2-stroke engine will make about twice the horsepower that a 4stroke would make. So, a 500cc 4stroke would make about.... 100hp, maybe a bit more. That would not be all that exxciting a race to watch.....unless, they were TURBOCHARGED!!
Forced induction would be the only way to make a 500cc 4stroke competitive with a 500cc 2stroke.

Hmmm.....I may be on to something here turbos and superchargers would make things interesting, no? It just may well be possible with today's 'electronic throttle control' and fuel-injection advancements in recent years...

<div class='quotetop'>QUOTE(waterfire @ Nov 19 2007, 02:05 PM) [snapback]101413[/snapback]<div class='quotemain'>
Ok I think I haven´t made myself clear. What I would like to know is why can´t we have 500cc with 4-strokes. The same for 125cc and 250cc.
Is it not possible with the present tech to maintain the same perfomance, or close?


Oh sorry ..... 500 4 strokes in place of the 250 2strokes ...... sorry.

Well Yeah originally I think they assumed 2 strokes were like 2 times the power but I think that has been somewhat reassessed now.

In that respect I thing Dirt bikes are in advance of street bikes ..... they originally said 500 ( 4s ) = 250

then it went 400
then 430
then I think the latest seems 450

so yeah 400 does seem a bit small

however .... most dirt bikes are single cylinder and there are advantages in multicylinders so maybe they think they will get simillar power from a 400 in a year of development ....


Good question really ..... sorry for the initial "not getting it" ..... but we have folk on here asking why they don't bring back the old 500cc 2 strokes ....


Edit..... Actually can anyone answer me this .... years ago I had a notion that the capacities 125, 250 and 500 were bound by some form of formula on piston sizes .... anyone know if this was the case??
If so maybe they are sticking to that sort of ideology too.??

The two-strokes are being ditched because the factories are no longer willing to plow money into developing technology they can't sell (due to emission regulations). The difference in CC is to compensate for 4-stroke engines being less powerful.

And nowdays it's even less likely for any 2-stroke return as it's no longer only regulations but even motor racing are starting to turn environment friendly.

And to tread starter. As mentioned before, only forced induction could make a 4-stroke as powerfull as a 2-stroke of the same capacity. I doubt turbo would do it due to lag and small size tubine and exhaust, but a super charger might be a possible way. But I doubt we will ever see a system like that. But maybe we will see MotoGP as 20 - 40 kg lighter bikes with a 600cc capasity. That would be kind of cool.
180BHP/110kg bikes that is faster than the superbikes would be nice and would make them more "true" prototypes than the current breed.

<div class='quotetop'>QUOTE(Tom @ Nov 19 2007, 12:09 PM) [snapback]101431[/snapback]<div class='quotemain'>
The two-strokes are being ditched because the factories are no longer willing to plow money into developing technology they can't sell (due to emission regulations). The difference in CC is to compensate for 4-stroke engines being less powerful.


Exactly!

In 2001 we had arrived at a situation in which there were practically no 2-strokes engines in stock production, due to the emission regulations in most countries, but all racing bikes were still using 2-strokes because they deliver roughly 160% the power of a 4-strokes of the same capacity (....not 200% as someone says...). That's the reason why 2-strokes had become dominant in racing in the first place, because of their superior power.

To make 4-strokes of 990 cc was overkill if the purpose was only to match the power of a 500 2-strokes. This became obvious when the 500 and 990 raced together - so the purpose must have been also to make the bikes more powerful than the 2-strokes.

The switch to 800 maybe brings the power of a 4-strokes engine more in correspondence with that of a 500cc 2-strokes bike, but I doubt it has made the bikes safer. What has made the bikes safer is TC, not the decrease in capacity.

<div class='quotetop'>QUOTE(J4rn0 @ Nov 19 2007, 12:14 PM) [snapback]101440[/snapback]<div class='quotemain'>
The switch to 800 maybe brings the power of a 4-strokes engine more in correspondence with that of a 500cc 2-strokes bike, but I doubt it has made the bikes safer. What has made the bikes safer is TC, not the decrease in capacity.


The safetey debate is a different story for another day, but i disagree with you on this.

<div class='quotetop'>QUOTE(Babelfish @ Nov 19 2007, 12:11 PM) [snapback]101438[/snapback]<div class='quotemain'>
And nowdays it's even less likely for any 2-stroke return as it's no longer only regulations but even motor racing are starting to turn environment friendly.

And to tread starter. As mentioned before, only forced induction could make a 4-stroke as powerfull as a 2-stroke of the same capacity. I doubt turbo would do it due to lag and small size tubine and exhaust, but a super charger might be a possible way. But I doubt we will ever see a system like that. But maybe we will see MotoGP as 20 - 40 kg lighter bikes with a 600cc capasity. That would be kind of cool.
180BHP/110kg bikes that is faster than the superbikes would be nice and would make them more "true" prototypes than the current breed.

Unfortunately this would probably put more of a premium on the rider's weight, something that I believe counts against rossi at the moment.

<div class='quotetop'>QUOTE(Tom @ Nov 19 2007, 01:16 PM) [snapback]101442[/snapback]<div class='quotemain'>
The safetey debate is a different story for another day, but i disagree with you on this.


OK, I'll wait for some other day to know how decreasing the capacity to 800cc has made the riding safer...

My opinion is simple: the switch to 4-strokes was overdue, because racing bikes could not continue to be something completely removed from production.

Apart from this basic change, all the rest was more or less dictated by mama Honda. They wanted to make sure their new 4-strokes bike would beat the old 2-strokes, so they made it 990cc. It did beat them!

Then, they realized everybody, even Yamaha, could make a 990cc bike with enough power to be competitive. They had lost an engineering advantage. So after 2004 (a nightmare year for them) they thought, let us make it more difficult, let's decrease the capacity to 800cc wich is a better match of the old 500 and will give us a technological edge - plus we have Pedrosa who is small, we'll make a super-compact bike and kick ... again.

Ducati and Stoner, however, have marred their plan, at least for one year. Let's see... ALl this is to say that safety was only a pretext for all these changes, never a real reason.

My opinion is simple: the switch to 4-strokes was overdue, because racing bikes could not continue to be something completely removed from production.

For sure.

But a stroke is the ultimate engine. So much power, so little moving parts - an incredible engine.

Perhaps they should have introduced an emissions test rather than banning them altogether? Then maybe the manufacturers would have concentrated on cleaning them up ?

Even the this years new rules are eating into innovation with the 4 stroke 4 cylinder rule. No more triples, 2 strokes, V5's etc

This is a prototype series after all.


Snorvey

4 Strokes sound better.

<div class='quotetop'>QUOTE(phleg @ Nov 19 2007, 04:22 PM) [snapback]101498[/snapback]<div class='quotemain'>
4 Strokes sound better.


Yeah, when they are set up as 'screamers'....these darn big-bang engines all sound like single-cylinder dirtbikes (4stroke, of course) on steroids

Now, when MotoGP came to Laguna in '05, if I remember correctly... the Yamaha R1-based WCM machine and the KR V-5 were shrieking like banshees!! Awesome sounds they were making!

All the other bikes sounded all too similar to one another...

<div class='quotetop'>QUOTE(michaelm @ Nov 19 2007, 02:12 PM) [snapback]101445[/snapback]<div class='quotemain'>
Unfortunately this would probably put more of a premium on the rider's weight, something that I believe counts against rossi at the moment.


I agree, not only Rossi though but anyone above 160cm and 50kg, but the cure is simple enough, minimum combined bike and rider weight as in 125. Even better, both a minimum bike weight and a minimum combined weight. The minimun bike weight will keep the cost down and cover the actual advantage a bigger guy have on those powerful machines. The minimum combined weight will stop guys like Pedrosa to get a too big advantage. You can see how pedrosa strugle, but also how fast his bike is compared to Hayden, so today I think the two balance out pretty well. But a smaller capasity and lower weight would change that.


<div class='quotetop'>QUOTE(J4rn0 @ Nov 19 2007, 03:09 PM) [snapback]101449[/snapback]<div class='quotemain'>
OK, I'll wait for some other day to know how decreasing the capacity to 800cc has made the riding safer...

My opinion is simple: the switch to 4-strokes was overdue, because racing bikes could not continue to be something completely removed from production.

Apart from this basic change, all the rest was more or less dictated by mama Honda. They wanted to make sure their new 4-strokes bike would beat the old 2-strokes, so they made it 990cc. It did beat them!

Then, they realized everybody, even Yamaha, could make a 990cc bike with enough power to be competitive. They had lost an engineering advantage.


You forgot how they dictated the nice weight limit on the 5 cyl configuration they had on the drawing board.

<div class='quotetop'>QUOTE(Snorvey @ Nov 20 2007, 07:52 AM) [snapback]101496[/snapback]<div class='quotemain'>
But a stroke is the ultimate engine. So much power, so little moving parts - an incredible engine.

Snorvey


But the one thing a 2 stroke can never be is .... as efficient as a 4 stroke .... I think that was a big reason for 4 strokes as well.

<div class='quotetop'>QUOTE(Babelfish @ Nov 20 2007, 01:26 AM) [snapback]101510[/snapback]<div class='quotemain'>
.............
You forgot how they dictated the nice weight limit on the 5 cyl configuration they had on the drawing board.


Interesting can you expand on this a little bit?