motocross action mag

[Turquine]

Dogger, it sounds like you are then implying that it simply cannot be done. I disagree. I very much agree with Sachs. But whether DI, or some other method, we have to stop accepting limitations as if the current state of development of the 2stroke engine is as far as it can go. If they put even half the effort into seriously developing the 2stroke as the big 4 have the 4stroke, you'd almost certainly be seeing bikes that were far superior in every respect to current 2stroke machines. Very little serious effort is going into them.

Dogger, I didn't mean to imply that I thought it was merely a conspiracy that 4strokes get better traction. I've ridden both types of bikes over the years and I'm well aware that this is generally true. This can be a liability to them at times, in deep sand, as I found out years ago on the old TT 500 Yamaha. That bike would often dig a hole and sit in it on sand hills that old 250 2strokes of the day, were simply skimming right up. Nevertheless, What I'm saying, is that we need to explore other avenues for getting power to the ground than simply rolling over and accepting having less power and hoping to overcome this by better handling. Flywheels, different tires, whatever. Simply because it hasn't been done doesn't mean it cannot be done. If so, then Project 250 and any other efforts of that type are simply wasting money and time, and we should just give in and buy a thumper.

If the AMA is not going to change the rules, we've got to come up with better 2stroke technology than we've currently been using. Make no mistake, the 4strokes will get faster and better. If we can't get folks to focus back on the 2stroke pretty soon, they may very well get the 4stroke to the point where it is equal to or better in power to even the same sized 2stroke -- as 2strokes currently sit. Even now, we can see this with the new KTM 350. Next thing you know, we may be seeing a revolutionary new thumper that is a 250, putting out every bit as much peak power as the current KTM 250 SX 2stroke. We've got to get the general public to where they are demanding 2strokes again, so that the big factories, or somebody with the wherewithal, will start putting some serious research and development into the engines. I honestly believe if this doesn't happen pretty soon, it never will, and the 2stroke truly will go extinct. I don't believe that making a 250 2stroke which can both out-accelerate a 450 4stroke, and get power to a dirt surface well enough to do so, is the equivalent of trying to make a square circle. It seems, however, that a number of posters on this site believe just that though, that it cannot be done. I'm positive it can.

[TMKIWI]

While i agree turuine that 4 strokes will get better i dont think they will be able to get them to the same horsepower level as the current 2 stroke in a mx bike.
For road racing yes. But MX is a totally diferent animal.
Peak horsepower is not the only goal.
Yes 250 4 strokes can make good horsepower these days but they need big rpm's to do it.
For them to make more power they need more rpm's and the motors are on the edge of current metallurgy capalbilities now.Thats why they blow up so spectaculary now. Any further exotic materials will just make them even more expensive.
If 250F's pulled even more rpm's then now they would have a shorter power band then what current 2 strokes have.
And thats the biggest complaint of smokers.
Again fine for road racing but counter productive on a MX track.
If you look at the torque outputs of current motors the 250F has about 19ft/lbs a 250 smoker has 28ft/lbs and a 450 has 31ft/lbs.
The 250 smoker needs to be able to put down on the ground easier.
I think a DI motor with maybe the Honda exp idea as well would work wonders.
The motor could by tuned to match a 450 but the DI system would make the motor less peaky and so more manageable.

[SachsGS]

If my memory is correct the BMEP of a 4s is higher then of a similar 2s which means a 4s is a slightly more efficient powerplant then a 2s. However,due to the 2s cycle, a 2s performs effectively twice as much work per unit time as a 4s. To offset this, the manufactures are spinning the 4s almost twice as fast as the 2s (never mind discpl. advantages). Herein lies the Achillie's Heel of a 4s,the motors are (as TMKIWI pointed out) virtually up against a brick wall in terms of current cost related technologies allowing any further increases in engine speed.

A highly tuned DI 2s would have significantly reduced lower rpm scavenging losses then a current 2s.A DI 2s would feel "very torquey" at lower rpms and then (due to injection timing lags still requiring an expansion chamber) would come on in a "rush" at higher rpms with slightly more peak power then a current 2s. Fuel economy would be significantly better and the motor would still have 2s "hit".

What this means, and I'm speculating here, is that a DI 250 2s would probaly match a 450 4s in terms of breadth of torque curve,generate similar peak hp figures and the peak torque values would exceed that of a 450 4s. All this with less weight and no fear of dropping a valve when you're hitting that next double (jump).

And so, and bear with me as I repeat myself, with DI technology I am certain we could beat the 4s's at their game within the framework of their rules. Somewhere on this planet somebody has the resources to make a next generation 2s MX'r a reality.

[tripleduh]

I have heard that L.A sleeve is proto typing a 330cc bolt on kit for the YZ250`s . 

[dogger315]

Dogger, it sounds like you are then implying that it simply cannot be done.

I don't mean to imply that.  I guess I'm not convinced that a fight against unfair rules
and a stacked deck (manufacturers) is a good idea.  I also don't think more power will
cure what ale's you.  I could probably write several boring pages on the pros and cons
concerning the horsepower debate but there is so much more to going fast.  That's
why the O' Show was able to beat all those works 250s and 500s heads up on a 125
at the des Nations years ago

I have raced all of the bikes we have discussed.  I switched to four strokes because it
was costing me a fortune to modify my 250 two strokes enough just to stay with a fast
guy on a STOCK 450F.  The four years I competed on the four strokes saw my race budget
double, my injury rate go up and my fun factor go down.  I wised up and switched back
to two strokes for good.

The purpose of the last paragraph is to show you and others, there are hundreds if not
thousands of people like me that have done the same and I believe it is a growing trend.
Regardless of the spooge you read in the "message controlled" media, two strokes are
alive and well.  One of the very popular series in SoCal right now is Marty Tripes 100cc
racing (all two strokes).

Instead of banging our heads against the wall trying to overcome arbitrary BS displacement
rules, I think we should consider the establishment of another sanctioning body that would
allows heads up racing.  That would put the fun back in racing by allowing all bikes to
compete in a 125, 250 and open class regardless of their exhaust note.  MX is a grass
roots kind of sport to begin with, we should go back to those "roots".  Since when should
the AMA and a collection of Japanese manufacturers dictate what kind of bikes we
ride/race? 

Let the big four rake in the profits from the ever escalating cost of the four strokes.  We
don't have to participate.  Eventually, they will price themselves out of reach for most
people.  This is a recurring theme in all forms of racing, one that is usually met with rule
changes to get cost under control:  F1, CART, even the AMA (remember works bikes?).
Sometimes the changes work, F1 is as popular as ever.  Sometimes the changes are a
disaster, does anybody care about the Indy 500 anymore?

This is just my two cents, another point of view and the way I would like to see this mess
play out.

dogger

[2stroker]

i think 250 two strokes should be in the 250 class!   and 500 2 strokes in the open class   and 125s in a 125 class,  not 250s in the open, and 125s in the 250s,   the classes should be judged on the CCs the bike has not the power

[KXwestYZ]

If there's anything to be leaned from those 4 strokes is that having a explosive hard hitting powerband is not realy necessary to turn out fast lap times.

Corner speed and traction is were it's at, not dragracing from turn to turn

If thats the case why do they need 2 x bigger engines to win over 2 strokes? wouldn't the traction & corner speed make them competative at a cc v cc level...  obviously not

[Suzuki TS250/185]

A 250 2 Stroke is, and always has been, fast enough to win if the rider has the skill to identify and use the characteristics of the bike to their greatest advantage.

Yes, there were times in 03 where RC had to work to pretty hard to stay in front of Kevin. But there were also plenty of times in supercross 04 including places like Daytona, where Reed toyed with him and his tractor bike and then slam-dunked them easily, and later on in 05 when poor K-Dub was almost lapped traffic for RC, Reed and Stewart on their 2 stroke mounts. And... The 4 strokes were just as powerful back then (05) as they are now. They couldn't compete against the 2 strokes that were on the line against them though.

I feel that the conversion of all the major players for SX 06 was probably driven by the actions and agendas of the manufacturers. Like maybe the Yamaha riders had a "Choice" up through 05, and then after that it became more of a "Yamaha pulled their support for Fred Andrews Racing because they wouldn't run a WR250F..." type situation. Whatever it is, it stinks, and it has made supercross considerably less exciting no matter what you hear TV announcers and race promoters say.

KTM 250sx helmet cam - tmc mx 8/16/09 250A 2nd moto

[msmola2002]

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