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Advanced 4-stroke? Whats advanced about cams, timing chains/gears and valves opening & closing? There isnt one piece of 'new' technology in those thumpers that I can see. For the most part no different than a typical Honda XR excepting water cooled. Only difference is they are just being ran to the very limit on tolerances - and that is how they are getting 'performance' out of them. Wind 'em tight and hope they dont grenade. Meaning they are turning super high RPMs, and in the Factory bikes, they are running very high compression and cam-grind specs that are doubtless bouncing the valve on the seat with higher lift/duration and steep ramp-rates on the lobes. That is why I had to run a Rev-Kit on my sprint car engine, when you open/close valves at those kinda RPMs and have that steep a ramp-rate, you are gonna bounce (and/or float) the valves if you dont use something to hold it all down.
If there is anything 'new' in those noisy thumpers, Id love to see it. But your gonna have to come up with some pretty cool stuff to impress this old dirt-tracker. Its all been done before on the dirt track, and in the end all you can do is make 'em lighter and wind 'em tighter.
I know Suzuki won't.
Advanced 4-stroke? Whats advanced about cams, timing chains/gears and valves opening & closing? There isnt one piece of 'new' technology in those thumpers that I can see. For the most part no different than a typical Honda XR excepting water cooled. Only difference is they are just being ran to the very limit on tolerances - and that is how they are getting 'performance' out of them. Wind 'em tight and hope they dont grenade. Meaning they are turning super high RPMs, and in the Factory bikes, they are running very high compression and cam-grind specs that are doubtless bouncing the valve on the seat with higher lift/duration and steep ramp-rates on the lobes. That is why I had to run a Rev-Kit on my sprint car engine, when you open/close valves at those kinda RPMs and have that steep a ramp-rate, you are gonna bounce (and/or float) the valves if you dont use something to hold it all down.
If there is anything 'new' in those noisy thumpers, Id love to see it. But your gonna have to come up with some pretty cool stuff to impress this old dirt-tracker. Its all been done before on the dirt track, and in the end all you can do is make 'em lighter and wind 'em tighter.[/quote:volazhi6]
While I'm really not a big fan of racing 4 stroke dirtbikes, you saying a CRF450 isn't much more than a XR400 with liquid cooling makes about as much sense as saying that a new YZ250 isn't much more than a DT1 with a radiator. Come on, you're smarter than that. Technology has benifited both the 2 stroke and the 4 stroke, but due to the 2 stroke being limited to a few niche markets (dirtbikes, pwc, snowmobiles, chainsaws ets), it hasn't seen the development the 4 stroke has. It wouldn't surprise me at all to learn that more money is thrown at a single Formula 1 car's 4 stroke engine in R&D in 1 year than KTM spends on ALL their 2 stroke R&D in 1 year.
Hey, think of it this way- you probably ran a SBC in your dirt track car, right? That basic motor was introduced in 1955. I don't care if you worked for GM, had Tinkerbell herself as a engineer and she had a whole bucket of magic pixy dust, the 1955 version of that motor would never make the power that your roundy-round motor did, right? There haven't ever been any "massive'" breakthroughs in the development of Chevy's V8, but rather steady improvements year after year. But after 40 years, that really adds up (and all the basic improvements made to the SBC's have been applied to every other 4 stroke). The 2 stroke simply hasn't received that kind of development.
You have hit on something significant with your RPM comments. Next to increasing displacement, raising the rpm level is the best way to make more HP, and the 4 stroke is better at reaching higher rpm's. Honda was hitting an obscene 18K with their 250cc Grand Prix racer- in 1966!
Understand, I'm not campaigning for the 4 stroke, I'm simply stating some facts. I personally think that MX racing was better off with only 2 strokes in there, and without question the off-road crowd was much better off with only playbike 4 strokes (not so loud or expensive to fix). But given the $ generated by 4 strokes for the mfg's, the unfair rules, and the "greening" of much of our society, I'm not surprised the 2 stroke is up against the wall, so to speak.
If the 2 stroke does well against the 4 stroke in MX racing when it's CC for CC, there's a pretty good chance we'll see a resurgance of pingers on the market. If not- you better stock up on parts, cause' it's a gonner.
I still stand by what I posted. Show me ONE piece of 'new' technology in a modern 4-stroke racer. Its the same old cam & valve design sped up expotentially to make power. If there IS anything they are tweaking is making valve train lighter and putting effort into flow characteristics to optimism volumetric efficiency. But thats not new anyway, its the same ole crapola that has been going on in sport/superbikes for decades anyway. They just are moving the torque curve around with cam grind to meet the needs of MX/SX. But is it new? Not even close. Heck they would resort to the old stand-by of raising compression if they could get away with it (because face it, every bubba out there on the dirt track, first thing they do is mill the heads and flirt with kissing a valve) but they cant do that because every weekend warrior bubba would detonate their engine into oblivion with that 93 octane pump sludge you get at the corner Exxon.
Im not trying to be argumentative, but I still dont see a damn thing 'new' about these new 4-stroke bike engines. Nothing. Its just a new/recent occurence to the motocross scene so people associate it with 'new'. Well, its not - its the same technology that farmed cotton in the 30s tweaked to fit in a dirtbike chassis.
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the advances in it taken from formula one produce some impressive results, that are even fairly reliable
but granted it is just "new and improved" nothing earth shattering in basic desgns.
matt fisher posted a very good,rational, and realistic description of "why" the dirt bike market is where its at.
quite, unusual for MD.
And you think a 4-stroke is new? Ive said it I cant remember how many times now; the whole notion of using the Otto Cycle to move a motorcycle around is antiquated as hell. Cams & valves, valve springs and locks, gears & chains, buckets & shims with lash that opens & closes. All this moving apparatus just to create energy to move a dirt bike forward. The two-stroke IS more advanced by default because it uses less parts to do the same job. Any engineer with a clue will tell you LESS moving parts is better, period. You wanna see advanced technology, go look at the Evinrude E-tec and get back to me on how 'advanced' a valve munching pig is.
So keep on poo-poo'ing the simple, reliable two-stroke for the 'new' 4-stroke. I have a 1938 Allis Chalmers 'B' that has the exact same design to get it around too, but I wouldnt call it cutting edge stuff.[/quote:d4smfvkp]
Really? You pick ANY 2 stroke bike against ANY 4 stroke, put them on an MX track and the 4 will win 99% of the tracks. Therefore 4 strokes are better motocross bikes than 2 strokes........................OH you want to talk about Supercross? Read previous sentence.
The 2 strokes are going to stay with the x games where they can compete.
Hmmm, do I want to race a two stroke against bikes with twice the displacement?
Tough "choice."[/quote:1ql09p1y]
What would you decide if they had the same displacement? cc VS cc[/quote:1ql09p1y]
Exactly, this 2 vs 4 thing is so old and it's been done to death. As far as I'm concerned people can ride what they want as long as it doesn't harm anyone else - 4 stroke riders can pay through the nose for their heavier, more expensive and less powerful (cc for cc) bikes as long as it does not affect me.
Unfortunately 4 stroke riders harm the sport due to excessive noise, which has resulted in many of my favourite tracks being closed. I can't blame the locals because I find the noise of the 4's offensive just as they do. Therefore another riders choice to ride a 4 stroke affects me.
There is only 1 solution and that is to make it a completely level playing field, and I mean completely level. In other words, strictly enforce the following...
1. displacement - a 250 races a 250 no matter what the engine design
2. emissions - set a limit, if a 2 stroke can't match the limit (cc for cc) then tough - change or develop the design, same goes for the 4 stroke
3. noise - as above - set a db limit that allows tracks to stay open and if either engine design cannot meet the limit then either improve the design, fit a q-pipe or stop racing them.
4. weight - drop this stupid minimum weight requirement - it may as well be a minimum number of strokes requirement to force riders to buy more expensive machines.
With all the above in place, over the next 5 years we will see which bike is best and give people a choice - if people prefer the hookup of the 4 stroke and are prepared to pay more money and sacrifice power and lightness/flickability then that is their choice. At least it will be a fair contest and if the 4 stroke wins according these rules then I will be the first one to buy one.
Wow, I didnt realize! Thanks for telling me how much I dont know about race engines. Here I was all thinking all the wrong stuff, whew. Thanks !
At least all the "wah wah i want to ride my 2 stroke wah wah" will stop.
At least all the "wah wah i want to ride my 2 stroke wah wah" will stop.[/quote:4leet07j]
Dont be mad that your 250 4 Stroke cant keep up with my 250 2 stroke. They both have the same CC's so whats the problem?
I didnt say anything about my speed. I was talking about the bikes. If you want to bring speed into this I vote one of these days there should be a MOTODRIVE race just to see where everyone stacks up on the track. Whos down???
Id line up if it was close enough. With clouds of Motul 800 belching from my exhaust.
Id line up if it was close enough. With clouds of Motul 800 belching from my exhaust.[/quote:4j86jad4]
Thats the spirit!
Id line up if it was close enough. With clouds of Motul 800 belching from my exhaust.[/quote:1x0ovahb]
I'll match your Motul 800, and raise you by mixing it with Sunoco 110 LEADED!!
KTM already has prototype of DI-2stroke. It is matter of time when new kind 2-stroke motocross bikes arrives and then it is payback time
Expensive, heavy and loud 4-stroke motors are old school stuff already.
I hope that 125 class don´t dead now when they are focused about 250vs.250. 125 class is very entertaiment class.
Pit Row
I still stand by what I posted. Show me ONE piece of 'new' technology in a modern 4-stroke racer. Its the same old cam & valve design sped up expotentially to make power. If there IS anything they are tweaking is making valve train lighter and putting effort into flow characteristics to optimism volumetric efficiency. But thats not new anyway, its the same ole crapola that has been going on in sport/superbikes for decades anyway. They just are moving the torque curve around with cam grind to meet the needs of MX/SX. But is it new? Not even close. Heck they would resort to the old stand-by of raising compression if they could get away with it (because face it, every bubba out there on the dirt track, first thing they do is mill the heads and flirt with kissing a valve) but they cant do that because every weekend warrior bubba would detonate their engine into oblivion with that 93 octane pump sludge you get at the corner Exxon.
Im not trying to be argumentative, but I still dont see a damn thing 'new' about these new 4-stroke bike engines. Nothing. Its just a new/recent occurence to the motocross scene so people associate it with 'new'. Well, its not - its the same technology that farmed cotton in the 30s tweaked to fit in a dirtbike chassis.[/quote:21xw2nvk]
Inadvertantly, you're making my point.
If viewed from a simplistic level, neither the 2 or 4 stroke has changed very much in decades. Your comments on high rpms, making them lighter, etc, all apply to both engine types. I'm saying that the top technology for 4 strokes far outstrips what passes as top technology in 2 strokes- thereby defining what the future will hold.
And when trying to define what engine is more "advanced", it doesn't make any sense to use what technology is currently being offered on production dirtbikes- because there's nothing truly advanced about any production dirtbike motor on the market today. Try comparing them to a production BMW car with it's continuously variable valve lift and duration- it's about like having 1000 different cam profiles sitting inside the cylinder head. Low rpm's get low lift and small duration for great emissions and torque, while high rpm's get much more lift and duration for big hp numbers. Works well enough that there's NO throttle body- it's wide open from air filter to exhaust tip like a diesel is. And that's on a production car, let alone pnuematic valves, variable intake runner lengths (R1 & R6 for example), and so much more.
Yes, a 1936 flathead Ford still has the same basic idea of piston, valves, cams, and block as a 2008 Ferrari F1 car, but there's a world of difference between the two. Look at the F1 car for an idea of where 4 stroke technology is headed (that does include both good and bad aspects).
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