Do you remember?

[Recovered]

Do you remember the 4 stroke nationals?
I do. They were GARBAGE (and that's an insult to garbage). Very low attandance, minimal coverage and mostly no name riders. Now were stuck with 12 times a year. Keep banging away on the AMA. Don't support manufacturers who don't support 2 strokes. I'm having a hard time with KTM, as it looks like they say one thing (they love 2 strokes) but they do another (have almost everyone in off-road racing on 4 strokes). Please don't tell me they are developing something for the future. They have competitive 2 strokes RIGHT NOW!

[JohnN]

I remember!! The four stroke Nationals were not very high on my list of interests, so I never paid much attention to them.

The "new" advanced four-strokes are so much better....

They're so much better that they need to be double the displacement of the two strokes they compete against! I must be from another planet because that does not make any sense to me.

It's not just the AMA, the Big 4 manufacturers have a huge say in what happens in Pro Motocross racing. From the information I have heard, if they don't get their way, they threaten to pull out of racing. So the AMA and the promoters give in and they get what they want.

 It's a vicious circle, that will not end until people make some changes and stand up for what they really believe is right. What do I mean by that? Well you'd never believe how many racers I talk to that currently race four-strokes because they feel they would be at such a disadvantage by racing the smaller two-stroke. The problem is that these guys prefer the two-stroke and feel they are forced to race the 4 bangers...

Another instance is attending the Pro Events. I've tried a few times over the years, mostly when I heard rumors that someone was going to attempt to compete with a two-stroke. Every single time I'm disappointed. Not just because there are no two strokes, but because the racing is so boring and deafeningly LOUD! So often it's like watching a conga line.

The worst is when a racer stalls, and he kicks, and kicks, and kicks, and kicks, and kicks and nothing happens. He basically gets a DNF because he can't start the bike because it's hot. What kind of crap is getting a DNF because you can't re-start your race bike? You don't mind of the guy broke his frame in half or a wheel exploded or even that the bike seized, but you DNF'd because you stalled? That sucks! Even more so for the fans. Remember James Stewart at Anaheim 1?

From the reports that I have heard, KTM has fuel injected (DI or EFI I don't know) two strokes ready to go. Test riders say they work great, but there is no real talk of when they will be released.

Yes all the manufacturers have competitive two strokes right now. They just choose to allow the four-strokes to be bigger so they win and can sell more of them to Joe Public....

Man I feel like a broken record! :'(

[JETZcorp]

Well, I have to hand it to the Big Four, they have done a lot to improve a shitty engine.  A while back (and I do mean a while!) I went to an AHRMA race in Eugene and the dominant guy that day was on an open-class Yamaha thumper.  He spent the entire day battling a Husqvarna 390, and all eyes were wondering just HOW in the HELL that guy kept the Husky from passing?  Everyone knew that Yamaha had far, far less power and a good fifty extra pounds to carry around.  It was generally concluded that this four-stroke guy must be the second-best racer in all of Vintage MX, behind only the one-armed bandit (who only has one arm, and places in the top three on every moto.)

The point is, looking at the numbers of the older four-strokes makes one marvel at how much they've advanced compared to how little two-strokes have.  I mean, Maico's 250 made 42 horses in '81, and if you buy a new YZ250 today, you'll get an extra four.  That's all that 28 years of advancement buys you in the engine department. But then, look at the difference between an early-80s four-joke and compare it to a modern thumper at you'll note a lot more of a change.  Whatever change was left over from the massive marketing swindle really did do a lot to improve the pigs.

Imagine if that could have been put into two-strokes!  Like I've quoted before, Honda could be running 400 horses per liter if they hadn't axed their innovative little two-stroke.  That means we could be seeing bikes on the MX track with more power than a Volkswagen, with no peakiness in the delivery.  On the other side of the coin, imagine what sort of impact it could've made if someone decided to crank it up to 3000cc and put it in, say, an NSX.  If the power increase was linear (which I don't believe) you'd be seeing somewhere in the very broad neighborhood of 1200hp stock.  Take it further, let's put a 500 cubic-inch version, run it on nitro and get some Don-Garlits-esque expert to tune it for the quarter-mile.  I don't see any reason why all the great cars of the world wouldn't be even better with a nice, injected two-stroke under the hood.

[Recovered]

Let's discuss the "actual" improvements made to the modern 4T.
1.Liquid cooling. This does entirely more for the internal combustion engine than I care to sit here and type out. Just like it did for 2T's. Compare late model 250F at a claimed 45-46 HP to the 55-56 hp from a late model 250 2T. That's a BUNCH, in fact, if you aks Mitch Payton (of Pro Circuit) it takes $25,000.00 to acheive those power levels with a minimum required DURABILITY. That's right...twenty five THOUSAND DOLLARS (not pesos) to get to that power level with SOME reliability. So what does that mean. Well, Mr. Payton said you need 3 (three) engines (at $25,000.00)   That means you have one in the bike, one in the trailer, ready to go, and one in being repaired. Is SEVENTY FIVE THOUSAND DOLLARS for 3 engines that won't make a full MX season (each engines survives one full MX race................maybe ) "modern" or better for the sport, or an improvement in ANY way, except it lined the pockets of the big 4, cottage aftermarket companies that would not even exist were it not for these turds and the magazines who slurped these up like they were the savior of off road motorcycling (Jody Weisel and the whole industry don't get a free pass from me now because they are coming around).
2. Engine geometry. Things such as bore/stroke ratio, rod/stroke ratio and other geometries. These factors influence cam timing, available valve area (net) exhaust demands that are easier to meet. I could go on. But we are talking serious things that 99.9% of riders have never heard of, let alone have a minimum of understanding. Don't get me started on camshafts and why early late model 4T's start easier that their late model counterparts (generally).

That's enough for now, but I can't defend a single point for single cylinder 4T dirt bikes.

I want to add one more point. There are some who think that spending in ANY form is good for the economy. This is false. People who didn't need new bikes, went out and bought one of the pigs for several reasons. Now, they are replaced more frequently, and maintainence is not nearly as enviromentally friendly.
I digress...

[JohnN]

Who perpetrated the idea that you need to buy a brand new bike every year?

While this was what was needed in the 1970's when the bikes were changing radically almost weekly and the cost of the bikes were around the $1,000 mark, this was sort of understandable.

Over the course of over 30 years the advancements made on bikes is incredible. In the early days you could wear things out like the foot peg mounts and you would need to replace the frame or weld to have level pegs! Now the bikes last a very long time.

The manufacturers struggle to come up with advancements that will entice customers to buy more and more. The media screams when something is not updated and the only changes are BNG (brand new graphics) but how much further can we go?

Even more important how much are we willing to pay for a motocross machine?

From the feedback that I have received from this site and by talking to people at the races, many folks keep their bikes for more than one year. They still run great and with the cost of the bikes being high, it's a smart thing to do.

For a few hundred dollars you can freshen your machine up for the new year. If looks are important to you, there are plastic kits available where you can make you bike look brand new or even change it to another color.

With a two stroke it's pretty easy for backyard mechanics to freshen up the motor and perform the required maintenance to get another year or two out of your machine.

It sounds like the market is changing.

What's really important here? Do you need the latest and the greatest? Or just the newest looking machine? Or do you care about performance more than anything else? Or is your purchase a fun machine?

Do two-strokes need fuel injection? It's kind of unknown at this point. Why? Because it's not on any motocross bikes yet. I don't know about you, but I'm not interested in buying something unless I KNOW that it will be an improvement that would work for me.

I know that from the tests and commentary I have heard about fuel injection, that it could improve the emissions significantly and help to ensure that motocross survives into the future. But still until I see a fuel injected bike that works well for motocross, I'm not interested.

Back to buying new bikes, everyone has their own reasons for buying, but why not look at this purchase like it's something that you will own for more than a year. Something that you are investing in and will be using for more than a year. How would that affect your decision?

I don't know about you but I look for the best VALUE for my money. Sometimes that's not always the cheapest one. It's the one that I feel will give the biggest bang for the buck!

[JETZcorp]

I would like to go back to the comment about water-cooling for a moment.  Here's my take on it.  In the '70s, cooling never seemed to be a problem.  Everybody had bikes with great big cylinders that did an excellent job just so long as you weren't taking it up to 9 grand in first and holding it there.  Weight was coming off the bikes in massive fashion, suspension was increasing, and power was becoming more plentiful and easy to manage.  Then, around 1980, they ran into a bit of a brick wall.  Anymore suspension would make a bike way too tall.  Anymore lightening of the frame would sacrifice handling, and something had to give way, especially in the 125 class where 8oz saved could mean victory.  So, they started hacking away at the cooling fins, until the cylinders were pale shadows of their former glory.  Weight was down (slightly - aluminum isn't that heavy) but cooling plummeted.  Everyone complained to high heaven about how power would go down over the course of a race.

Aha!  A marketing trick was on the horizon!  Water cooling would provide all the cooling you needed for a long race, and all you had to do was accept a bit of extra weight (hey, what?) and tote around a bunch of fluid and some delicate radiators.  And by the way, those radiators have to be mounted high-up, to avoid rocks and make the center-of-gravity as awkward as possible.  Then, bang!  The cooling problem (which wasn't there five years before) was fixed.

Open-bike cooling in 1974:
http://www.amsracing.com/index/large_pix/new-bikes-001.jpg

Open-bike cooling in 1982:
http://motorbikearchives.com/images/thumbnails/bike%20tests/1981%20Honda%20CR450R/1981-Honda-CR450R-3_4108b63dc969dc6c71dc1b3592f90790.jpg

Open-bike cooling in 1986:
http://www.vintagefactory.com/1986%20cr500.jpg

[Recovered]

There is WAY more to liquid cooling that what you are supposing. Look at a Bultaco head, a Maico, maybe a CZ, Husky or any jap bike and then look at 99.999% of liquid cooled heads (looking at the combustion chamber), then, see if you can dig up some SAE papers on 2 stroke engine design.

You would learn more than I want to type here.

[JohnN]

JetZcorp, I'm going to have to disagree with you on the water-cooling thing.

Since I don't know all the technical reasons like madscientist does, I stick to what I do know.

Back in the stone age 1975 - 1976 when the Pro Motocross races were 40 minutes plus two laps, the 125's especially suffered from power loss due to heat and many had seizure problems. The introduction of watercooling allowed the 125's to run more reliably and for longer periods of time before experiencing power loss.

The benefits were real. Even in local racing at the time with shorter motos, (15 to 20 minutes) the fast guys would experience the same benefits. Yes I was one of the first buyers of the 1981 Yamaha YZ125 water bike. Even with the extra weight up high on the triple clamps the bike handled well. Another side benefit was that the engine was quieter than the air cooled bikes.

Plus they looked so damn cool! And it looked like you had a toy engine instead of a racing machine.

I just was treated to a tour of Hugh's Bultaco and one of the motors there was a factory works motor used by Jim Pomeroy. Hugh handed just the head to me and I almost dropped it! It weighed almost 15 pounds!! This was an Open bike head and a factory part at that, and in comparison the water cooled heads weigh much, much less than that.

My feeling is that water cooling was a step forward. At the beginning there were some issues, but as it was refined, it made a huge difference.

[jft67x]

i think that 4t is SLOWER than 2t. in off road i raced my kdx200 an outdated trail bike against klx 300s . the tanks were getting stuck. i loved there faces when a 90 pound kid flew past them on a outdated trail bike

[Out of Order]

$25,000 for a four stroke engine with all the goodies to last.... let me see... maybe one moto. But I could rebuild my two strokes top end in 10-15 minutes for about $150-200. I will keep my two stroke please. The 4 poke is just to much up keep, plus rebuilding the top end every 20 hours(the same for my two strokes). I'm afraid to even touch the CRF250 engine with all the tiny top end parts like the cam, followers, springs, valves, and other precision made parts.