Why 4-Strokes?

It was easier to build and sell bikes the EPA would like and pass on the cost to the consumer, who was willing to pay it.

In other motorsports, the buyers werent buying the hype, and where weight is a concern, 2 strokes still rule, aka Power boats/outboards.

On top of that, the OEMS made 2 strokes burn cleaner than the 4s, with more power and easily got CARB approved.

Motocross racers have been conditioned to expect something new from the OEM's every few years and two stroke development was nearing the end of it's curve. Oversized four stoke engines gave the OEM's something new to market to the masses and because the economy was booming from 98-08, the consumer didn't mind paying for the 20% price increase that came with all the extra moving parts.

Actually the price increase makes sense if the bikes are sold by the pound just like potatoes or meat.

"...and apparently forced everyone to buy them."

Nobody held a gun to my head when I walkd in the Moto shop. The consumer is to blame. The rules said we could run a 250 4 stroke in the 125 class so we did. Racer's are always looking for an advantage, the 4 stoke was an advantage.

"Global Warming/Climate Change" has given rise to a Political Climate that mandates a change towrds "Cleaner Technologies"...

2-Strokes have been branded "Dirty"...so...the rest is history.

Funnything: The Question about "Resources" and how much of those resourcres go into keepin' a thumper runnin' v. a 2-stroke...has THAT been asked and Answered?

There are parallels in this argument that are jus' like the Hybrid v. effecient "typical" std internal combustion engine comparo.

Oh, well...the battle's been "written", played out and "Won"...by the Manufacturers and their "Masters" (Masters=Politicians and Global Opinion of the Ignorant Masses...which is "us").

On top of that, the OEMS made 2 strokes burn cleaner than the 4s, with more power and easily got CARB approved.



Two strokes are only going to burn cleaner if the fuel is mixed properly, and the jetting is spot on. That's a lot to ask of the general public, or weekend warrior.



Hell



From the sound of comments of this board, a good number of people don't even have the ability to properly perform the minor maintenance on a four stroke to keep it from shelling.

"From the sound of comments of this board, a good number of people don't even have the ability to properly perform the minor maintenance on a four stroke to keep it from shelling."

Clean oil and air filters are a tall order....

Yes, hence...the common contirbutors to CRF250R valve-train failures...

It also has alot to do with cost cutting to increase profit margins.. If the only 2 strokes you make are only usable on closed courses, you have to develope and make parts for that line of motorcycles, plus every other line you make(street/off road/watercraft).. Since 4 strokes are the only thing legal to use on some state lands, or waterways, the 4 stroke appeals to a larger market. Because of this the manufactures are building motorcycles that can share parts with other bikes in their product line.. This saves them money since the part has to only be engineered once, and used on several models.. They also save money on the parts as its cheaper to mass manufacture or purchase in larger quantities..

This concept is what made KTM's enduro bikes so dominate for so long, as they were basically their MX bike, with a larger tank, and different susp. settings

The reason is simple. Four strokes have twice the amount of moving parts than a two stroke so they no they will make a ton more money in the long run off the four strokes.

EFI 2 strokes have been around since the mid 80's.

Camp, 2 strokes werent at the development curve, its just the MC side failed to embrace EFI at a cost of 300 bucks back then.

Nowadays, EFI, DFI, Cleanfire etc is just that much better.

Because they are cheaper, more fun, more dependable, easier to work on, and have made the racing better.

Get over your two stroke addiction -- a million two stroke posts aren't going to change the cold, hard facts that four strokes are here, and they're here to stay for a while. It gets pathetic after a while.

deets i want some of the stuff you are having.

From my understanding, the rules allowed a displacement advantage to four-strokes, but "way back then", that was a joke, no one ever thought a four-stroke could be made competitive.

"Why did Yamaha exploit the rulebook?", is the big question. Was it because they knew they could build a four-stroke that would be faster, and with more tractible power, with that kind of a displacement advantage? Or was it that with the EPA rules or whatever, they were being "convinced" to try to build it?

Either way, Yamaha built it, it was doubted at first, but then people saw that it could indeed work. Remember '98 and '99? Yes, you saw some YZ400Fs out there, but they were rare. It wasn't an overnight switch in the big bore class.

Then Yamaha hit the 125 class with the first 250F, and man, what a game-changer that was. I think that was really major, everyone switched over because of the horsepower and torque advantage provided to a motor with double the displacement.

I was one of those guys. I had been a big-bore guy forever. I did my time on two-strokes, mostly 250s. I switched to a '99 YZ400F, but I got hurt pretty good, so I decided a 125 might keep me out of trouble. It kinda did, but jumping the thing was erratic for me, sometimes nose-high, sometimes nose-low. A friend had a 250F. I tried it, and hated it! I just couldn't see liking that thing. He had it set up way too stiff for my liking. I could hardly ride it.

Time passed, the 125 lost some luster as I crashed it quite a bit, and was generally more out of control. I finally decided to get a 250F, as it seemed like a nice tradeoff between "more power, but not too much power", and I had visions of grandeur of my "cheater bike" winning races.

This changed my riding forever. The 250F, when properly set up for a rider, is a great bike. It has very tractable power, and jumps very predictably. I just love mine.

So I think part of the success of the four-stroke is that it also "dumbs down" the experience. I'm just guessing, but I think it's like how some bike riders diss quad riders; "it's too easy". (personally, I disagree with that on a motocross track, I would never jump one of those things like those guys do!!!!) But anyway, I think some two-stroke riders don't have respect for four-stroke riders, because they are "too easy" to ride.

For me, it just makes it more fun. I'm 38 years old. I've never been awesome on a two-stroke. I guess I"ve never been awesome on a four-stroke either, but I'm way more in control.

Yesterday, myself, another friend, and Sparkalounger all went out on the ice to ride. Now granted, Sparky's 100cc Vintage Yamaha was not studded nearly as well as our XR100s; so it was way more "slidey". However, it was just so much easier to ride the XR100! On the XR100, the torque is not really there if you're not in the right gear, but yet amazingly more so than if I had the Yamaha 100 in the wrong gear (just nothing there).

Also, I found out yesterday that my throttle control sucks. On the XR100, once the turn-in is done, you can pretty much hold it wide open. On the two-stroke, that's not such a hot idea! Rolling the throttle is better, so the power doesn't come on so abruptly.

Could they build a two-stroke 100cc that would be just like my XR100, but superior in every part of the power curve? Probably, but I haven't ridden it yet. Every time I get on a small-bore two-stroke, it's the same... nothing nothing nothing OH YEAH HERE IT ALL COMES!!!! I like to have the power come on gradually, and controllably. Could they build a bigger bore two-stroke that makes me happy like that? Probably, but I haven't ridden it yet. I know I'm a wuss, but it's just too "zippy" of power for me, even two-strokes with flywheel weights and taller gearing. This old Vet rider just prefers the smooth, controllable nature of the four-stroke.

So I am just one of those consumers who spoke with his pocketbook. I don't consider myself a "sheeple" or whatever the haters like to call people who purchase four-strokes. I've tried both, and for my quality of riding, I prefer the four-stroke. "Just learn how to ride better, and the two-stroke is superior!" I've been riding for (sheesh, I hate to say this) over twenty years now, so when will I "get it"? I think some of us just weren't born Jeremy McGrath. I wish I was, but I wasn't; so I purchase what makes ME the most in control and have the most fun with the least injuries.

Also, my maintenance costs have been basically the same. I don't buy two-stroke oil any more, but I use more engine oil because I change it more often. I have not had a catostrophic top end blow-up. I have been riding Yamaha four-stroke 250Fs since 2003 (a 2003, 2006, and now a 2009). No valve-eating going on here. The valves barely moved. I did all my own work on my two-strokes. With getting a four-stroke, I had to learn how to adjust valves. That was not exactly rocket science, even I caught on quickly. Doing rebuilds just took a little more time, but same parts; just the piston and rings.

So in conclusion, I think that's how they got started in motocross; the rules that no one thought would ever be exploited, talk to Yamaha or the AMA on how that ball got rolling. Another interesting question might be "when did the rules change to allow such a huge displacement limit?". Has this been going on forever, or did it change in the late nineties? That would point more towards the AMA if the rules changed "recently".

My experience on a 250F and my XR100 summarize why I stay on a four-stroke; they are just plain easier to ride (for me). Since they are easier, I have more fun, and feel more "like a rock star". I'm not scared as much about losing control, and I can concentrate more on the track in front of me.

Two-strokes are fun for sure, it's rider preference I believe, and I think we should allow equal displacement in Pro Racing like we do in the amateur ranks. I just moved up to B class, but at least in the C class, it didn't matter what you rode (we have equal displacement rules in AMA amateur racing). The best rider won, the bike was irrelevant.

Because the AMA gave them an unfair displacement advantage and the OEM's decided to take advantage of it.
End of story.

I think Honda has always liked 4-strokes. Their 4-stroke line has always sold good. Of course Yamaha saw the loop hole in the AMA rule book and used it to their advantage. Some of the other manufacturers were probably wanting to produce them anyway, so this was more than enough reason.

Was it a loophole, or was there a change in the rule?

I never, ever, heard of letting a 350 or 400 4 stroke run in the 250 class.

Somewhere, and I think it had to be above the AMA, somewhere the FIM
and the big 4 came to an understanding.

Call it what you want.

I forgot to add excellent resale on the small bores and aftermarket accessories are much cheaper as well.

You would be surprised how many people can't change an air filter with out contaminating the air boot. Two strokes can take a little abuse like that, a four strokes can't.

4 strokes have 1-2 advantages and about 10 disadvantages over 2 strokes.
make a list of pros and cons of 2 vs 4 and see what you get.

pretty much all 4 strokes got going is that they'er easyer to ride

The AMA went four strokes because Honda wanted it! Remember they did control AMA during that period. Honda was forced to make two strokes back in the day. I read somewhere the pres of Honda stated they were a four stroke company.

Several years back I went to a KTM dealer show when a big wig spoke. He stated in Europe they were losing riders due to the repair cost of the 250f's. He also stated there needed a transition bike from 85/105 to 250f. The young riders were getting hurt and losing interest in the sport. He like all of us want the sport to grow.

Nailed it.

Regardless of the reason, 2-strokes are wanted now more than ever, and hated now more than ever (by the Big 4/ and certain members of the AMA - not all the AMA is against the 2-stroke).

This thread is entertaining.

How you guys can substantiate some of the comments here is beyond me. It's like you have deep insight into the minds of the design teams in the factories.

Defintely a good point.

all I know is I used to buy a new 2 stroke every couple years. Not the case with the thumper.

its the internet age. the age of "this is how i think something should be, so thats how it is" quickly followed by "the more I say it, the more truthiness it becomes....in my mind"

1st there was 4 strokes, then there was 2 strokes, then there was 4 strokes, then there was .........

Don't worry, sit back & relax, the machine of your liking will be around - or back around - shortly.

I think I'll bookmark this thread. You've got all the conspiracy theories and other lame reasons in one page.