Why not 2-strokes anymore??

[longtime coming]

To say that four strokes will rule forever and two strokes are dead is ridiculous. Everything changes back eventually. Original thinking is very rare. It is all about selling stuff. No more. No less. If it wasn't, supercross racing would not exist.

Simple, effective engineering is always the best, but not necessarily the most lucrative or stylish.

my 2 cents :ride:

 

[ignition retard]

I think the manufacturers should compromise and come out with a 3 stroke to make everyone happy.

 

[steve.emma]

Some people parrot what they read in the magazines or online, and others know things from actual experience.
Some know things from research or experiments that comes from being around bikes or in the industry for many years, not just a couple.

i agree, some people on here are just repeating any old rubbish that they have read or heard..... doesn't mean that they are wrong though. Especially when the thread is about a subject that has only been a fairly recent occurence.
As for experience in the industry, you're right cant be beat. However some things can be understood without years of first hand knowledge and if that helps form an opinion then we are all the better for it.
For example ive never met Micheal Jackson but i wouldnt let him babysit my kids.

 

[mkelly04]

His cornering was much faster on the 125 but he had a major disadvantage when running down straights or on hilly tracks.

I thought the same thing when I switched from my 250 2-stroke to my 450..... But when I paced myself through the corners following a friend I'm much faster on the 450.

I think the 2-strokes just sound faster, and of course when you dump the clutch and blow up a berm it looks fast........ But that just means you are losing traction :)

 

[XRpredator]

I think the 2-strokes just sound faster, and of course when you dump the clutch and blow up a berm it looks fast........ But that just means you are losing traction :)

BINGO!

 

[flynbryan]

I could never make my Crf corner like any of my 2-strokes and I had it for 2 years. The two motor styles just corner differently. Some can adapt and some can not. I can not.

 

[Mully]

i agree, some people on here are just repeating any old rubbish that they have read or heard..... doesn't mean that they are wrong though. Especially when the thread is about a subject that has only been a fairly recent occurence.
As for experience in the industry, you're right cant be beat. However some things can be understood without years of first hand knowledge and if that helps form an opinion then we are all the better for it.
For example ive never met Micheal Jackson but i wouldnt let him babysit my kids.

I agree with your post almost entirely.

However, if for example I am looking for a new 4 stroke for the woods, and someone says: "I would suggest wr250f, or the crf250x, or the 250xc-f, or the beta". I have to think, now how does this person know about the new beta?? Then I see the same person suggest to someone else what type of motocross bike they should buy and suggests 4 or 5 to them. At that point I have to call "shenanigans". Because I know that person is doing nothing but parroting what the magazines editors are "claiming" therefore this person has no opinion of their own. There opinion would be better received if it were based on "REAL" knowledge or experience.

Mully

 

[XRpredator]

For example ive never met Micheal Jackson but i wouldnt let him babysit my kids.

I've never ridden a KX250, but I'd never let Michael Jackson babysit my kids either.

 

[2-Strokes 4-ever]

The single best thing we can do to keep the 2stroke alive is.........buy them. If I manufactured off-road bikes, I'd make what sells. Even I know that, (and I often only have one oar in the water.)

 

[Rich Rohrich]

The single best thing we can do to keep the 2stroke alive is.........buy them.

It's nice to see SOMEONE finally gets it. :cool:

 

[2-Strokes 4-ever]

Charmichael won in 05 on a 2 stroke didn't he?

The reason for thumprs... EPA and tree huggers. Plus dealers and manufacturers like all the new parts and service revenue.

Actually, (based on what I read :think: ) RC made the switch to the RMZ when he saw his times through the whoops were much better than on the RM.

 

[DieselTech]

Well, isn't this an interesting discussion.....


I am by no means an expert on anything, but here goes.....

IMO, the OEM's will produce and sell whatever makes them a profit - need proof? Look at scooters. They obviously sell, therefore they keep making them. I'd never buy one - I'd buy a 250 Ninja instead. But, somebody out there likes them....

As for the displacement advantage, there's a few ways to look at it. First off, a two-stroke can theoretically produce twice the power of a comparably sized 4 stroke. However, due to physics, this just isn't reality. So, that's part of the justification for the "double displacement". If you look at dyno charts of 2 vs. 4 strokes, the 2 strokes produce more power than the 4's if displacement is equal. However, given the current displacement advantage, the 4 strokes actually have equal or more power than the 2 strokes due to a larger displacement. Also, the power delivery is different; it is more linear, and many beginning and intermediate riders find them easier to ride because of this fact.

When I wa 16, I had 2 bikes (both street-legal enduros): a 1986 Suzuki SP125 (4 stroke), and a 1979 Suzuki TS125 (2 stroke). The 2 stroke had more power, and was more fun to ride, so long as the jumps were small (the suspension sucked - it had twin rear shocks!!!); it was faster, accelerated harder, and was lighter. It also required more clutch work, especially in the sand (I grew up in FL). The SP was heavier, had better suspension, and was better on fuel mileage. Both bikes were air-cooled, BTW. I had always wanted to put the TS motor in the SP......best of both worlds. Now, it I would have had a 250 4-stroke motor in the SP, things might have been different, at least power-wise.

I'm 35, and I own a total of 6 machines right now: a '99 Banshee, an '04 DVX400, an '06 LTZ400, an '05 Blaster, an '05 KXF250, and an '04 CR250R. As you can see, a mix of 2 and 4 strokes. I personally like things about all of them, but my favorites are the 2 strokes. The midrange hit is awesome, and I like the sound. As far as racing goes, maybe I'd be faster on a 450 as compared to my CR, but how would I know, unless I go buy one? I don't because they have the potential to cost more to maintain (when raced). Notice I said potential.

If there was no displacement advantage for 4-strokes, they would not be competitive. The logic behind the ruling seems to have some validity, but in reality it is not quite fair, IMO. However, they say it's 90% rider and 10% bike, right? Maybe when all the riders are equal, the 4-strokes offer an advantage that is measurable (and wins races).

One thing is for sure; they ARE louder. And that certainly doesn't help us keep places to ride. Adding to this is the fact that alot of riders think they need to pipe them and get more power, when in fact they probably have more than enough power as it is. Image - it's a big thing.

Ok......I'm done now.

 

[2strokerfun]

Based on what I've seen from that red-headed kid on the Pro Circuit Kawasaki 250f do last year, I might be convinced a modern high-zoot 4 stroke could even be competitive with the same displacement.
Of course, I still love the twin shock bikes--I like having my kidneys shaken, not stirred !!

 

[DieselTech]

Based on what I've seen from that red-headed kid on the Pro Circuit Kawasaki 250f do last year, I might be convinced a modern high-zoot 4 stroke could even be competitive with the same displacement.

This is proof of the 90/10 rule.

 

[wileyE]

Because a four stroke fires every other stroke vs. every stroke it has to do something else twice to be "equal" .

1. It has to be twice as many cc's. (rules have allowed this)
or
2. It has to have twice the compression (because of it's wasted stroke cooling effect 4 stroke can run higher compression on the same fuel)
or
3. it has to rpm twice as high (most race 4 strokes do rpm higher than comparable two stroke)


The modern 4 strokes are able to utilize all 3 "equalizers" to their advantage, though class rules were set purely on displacement. There- in lies the advantage. Another small advantage came when unleaded race fuel was mandated , something that hurt the 2 strokes worse than the 4's.

 

[ignition retard]

Another reason the fours can make more power with less than half the displacement, RPMs being equal is maybe that the power stroke on a 4 lasts longer with regards to crankshaft rotation than on a 2, because once the piston goes past the exhaust port, its over. Granted on the 4stroke the exhaust valve probably opens before BDC but its still longer than the 2stroke. The 2stroke has the advantage of expansion chamber enhanced induction, but this i think is also limited by the time that transfer ports are uncovered on the upstroke, thereby reducing, the intake stroke length.

 

[steve.emma]

while conversation has turned to the technical side of things for a moment...why is the displacement for the 2stroke taken as the swept volume? i.e. 125cc or 250cc etc..
i mean a 2stroke engine can only compress what air fuel mixture is trapped after the exhaust port is closed, therefore not as many cc's as the swept volume.
yes i know (sorry "understand")that a 2stroke can exceed 100% volumetric efficiency when using a tuned expansion chamber etc.. but this is only for part of their rev range, not all of it,so i dont see how they are of "equal" power at half the cc's of the 4stroke counterparts. maybe someone on here can enlighten me? :think:

 

[Rich Rohrich]

why is the displacement for the 2stroke taken as the swept volume? i.e. 125cc or 250cc etc..
i mean a 2stroke engine can only compress what air fuel mixture is trapped after the exhaust port is closed, therefore not as many cc's as the swept volume.

The same is true for a four-stroke. The trapped volume that is compressed is determined by the intake valve close timing. The intake valve closes well past bottom dead center, and the piston travels a good distance before the intake valve is seated and actual compression starts. This tends to be only about 95-115 degrees of the available 180 degrees of crank rotation on modern race four-strokes.

 

[SpDyKen]

Off of the mechanical/technical aspect of this topic for a moment;

Keith McCarty is quoted in Cycle News (Jan.16th, issue#2; "Downsizing MX/SX," by Henny Ray Abrams.) as saying "The 250 class is one of the most expensive classes to be in due to the amount of money you must spend to make a competitive engine," he said. "A Pro Circuit engine is $10,000. if you want to go buy it. I can tell you that people aren't spending $10,000. on a 450. ...."

So, my questions are relating to costs. For a privateer;

- How many of these $10K 250F engines would one need to contest an entire season? What would one need to budget to properly maintain these racing engines for a season?

- Just how much $ would one need to build & maintain a 450F to the same standards?

- What would a reasonable budget be to buy and maintain a race-prepped 125/144cc two stroke engine, for an entire season of Nationals? How much $ for a 250T?

My opinion:

Racers will race whatever the sanctioning entity tells them they have to, based on the rules that are (arbitrarily) written & enforced. Period.

The AMA got us to this point, by setting forth the current rules. Not the federal government, the manufacturers, or anyone else. Their decisions, (be they good, bad, or indecisive,) from today on, will determine the direction of racing in the future. Some will blame the FIM. Bunk. Our (supposedly) member owned & run AMA is solely responsible for all motorcycle racing's direction, both past and present, in the USA. Leadership, or the (historical,) lack of leadership, by the current 'powers that be' in the AMA, will decide what racebikes (MX/SX, and all, including race 'replica', etc.,) are in our future, here in the US.

As always, just my $00.02 worth.
Regards, Ken W.

 

[youngr51]

Because a four stroke fires every other stroke vs. every stroke it has to do something else twice to be "equal" .

1. It has to be twice as many cc's. (rules have allowed this)
or
2. It has to have twice the compression (because of it's wasted stroke cooling effect 4 stroke can run higher compression on the same fuel)
or
3. it has to rpm twice as high (most race 4 strokes do rpm higher than comparable two stroke)


The modern 4 strokes are able to utilize all 3 "equalizers" to their advantage, though class rules were set purely on displacement. There- in lies the advantage. Another small advantage came when unleaded race fuel was mandated , something that hurt the 2 strokes worse than the 4's.

HhhhMmmmmmhhhhhhmmmmmmm :rotfl: 2 strokes are not dead yet. The technology is out there, take a look at kart engines, rotary valve induction has many possabliltys

 

[ignition retard]

why is the displacement for the 2stroke taken as the swept volume? i mean a 2stroke engine can only compress what air fuel mixture is trapped after the exhaust port is closed, therefore not as many cc's as the swept volume.

If it were measured that way displacement would be a function of port timing. So perhaps the method used is just the least complicated.

 

[DieselTech]

So, my questions are relating to costs. For a privateer;

- How many of these $10K 250F engines would one need to contest an entire season? What would one need to budget to properly maintain these racing engines for a season?

- Just how much $ would one need to build & maintain a 450F to the same standards?

- What would a reasonable budget be to buy and maintain a race-prepped 125/144cc two stroke engine, for an entire season of Nationals? How much $ for a 250T?

As Ken has pointed out, the 4T's can potentially be way more expensive to race, especially in the Lites class. When that money comes directly out of your own pocket, a 2T makes sense, regardless of the technical aspects and what not. Overall costs can be a huge factor. It'd be interesting to hear some feedback from some of the Pro privateers, such as Nick Wey or Gavin Grayck, in regards to these costs.

I personally know a local kid that got motor work done by PC, and his dad spent $4k - so it wasn't a Pro level motor. This kid races in the Novice class locally, and placed 22nd for the season in his class. He had some top-10 finishes, his best was 3rd. I also know a few of the other kids in his class, and they don't have a $4k PC motor in their bike, yet they are doing as well as, or better than he is. So, is he doing as well as he is because he got the motor work done, or was it a waste of money (as far as increasing his lap times and therefore allowing him to do better)? My guess - waste of money. I really think it's 90% rider. Watch any Pro level MX/SX event - the bikes have got to be darn near equal in terms of power, handling, etc., yet the top riders are lapping the others! I'd be willing to bet that RC, RV, CR, JS, etc. could still win races on a stock bike.

 

[zaneyzrex]

the only reason 2 strokes died is cause of politics and people being told lies. theres technology out there that could have 2 strokes running as clean if not cleaner than 4 strokes. as the baja guys. simple as that.

 

[Isobareng]

This current production trend is at the least a big set back to 2 stroke racing but there is a good chance that some one will be continuing the development of the 2 stroke engine in the future. It would fun to watch the next generations of 2 strokes develop. Maybe something in the range of displacements that would keep them equally competitive, maybe with fuel injection, maybe with some means of traction control. Technology is ever changing. What ever format is dominate 5 ,10 or 20 years from now the price tag and the complexity of the weekly maintenance in the range of the average consumer will be an important factor to keep the sport alive.

D

 

[oldguy]

I personally know a local kid that got motor work done by PC, and his dad spent $4k - so it wasn't a Pro level motor. This kid races in the Novice class locally, and placed 22nd for the season in his class. He had some top-10 finishes, his best was 3rd. I also know a few of the other kids in his class, and they don't have a $4k PC motor in their bike, yet they are doing as well as, or better than he is. So, is he doing as well as he is because he got the motor work done, or was it a waste of money (as far as increasing his lap times and therefore allowing him to do better)? My guess - waste of money. I really think it's 90% rider. Watch any Pro level MX/SX event - the bikes have got to be darn near equal in terms of power, handling, etc., yet the top riders are lapping the others! I'd be willing to bet that RC, RV, CR, JS, etc. could still win races on a stock bike.

I think that dad had more money then brains. His kid needs track time and practice more then the engine mods. I see kids running $3000 suspensions and who knows how much $$$ engine mods to run mid pack. The dads love to brag how much they spent modding the bike but when asked how often the kid rides they get a bit shy.
My son is fast but by far not the fastest in our district in his class usually finished in the top 5 last season (this year he is bumping into A and I don't think he will see consistant top 5 for a while). We maintain his bikes and have Eric Gorr do simple mods more for durability then for speed. There is no way my son is hitting his bikes potetial top purformance on a steady basis so why waste the money?
I attribute his results not to the bike mods but rather the fact he twists the throttle farther and longer then most kids he raced last year. I attribute the durability of the engines to Eric Gorr's knowledge.