OK EVO,it was your idea........

[bearorso]

That KTMs 2t are the 'high end' of (relatively) volume production 2ts, shows how stagnant 2ts have become.

They (the engine modules) are pretty much the same vintage as the YZs. You can't regard a 250 /300 engine module that can have a 380 top end and crank, with little modification (crank end / one crank bearing?) required, a hugely different one to that of the 360 /380.  Yes, they slimmed / shrunk it down, dropped some weight, and did detail changes, but nothing like what KTM did with their 4t engines. Count up how many 4t engine types, just in the Dirt bike side of things, that KTM have made (include the 2 'Berg engines - the 'all in', vertically split unit , and the sloper).

It's been a result of rules that favour 4ts - capacity- and the subsequent loss of "competition", for KTMs 2ts.

Things are changing, finally, with new 2ts being produced. Though, they are not earth shattering technical innovations - pretty much just slightly refined 2ts - if that. But, they Will provide some competition, so they will, I believe, start to push development further. KTM will have to stop sitting back and raking in the dollars so easily, with regards to their 2ts. Finally. A Good Thing for All 2t enthusiasts.

"Competition", does that. The Beta, and the Sherco, are a great re-start of competition, within 2t ranks. A heck of a lot more-so than the Ossa, as they have gone into the Enduro market, before Ossa, and, they are bigger /stronger companies. Though, quite small compared to KTM, of course.

The  much, and justly, revered (and quite old aged) SSS suspension, deserves it's reputation - it works very, very well. Still above the std , latest model WP units - and that's coming from a bloke that uses WP CC front forks (though, much modified / set up for my uses).

[factoryX]

I'm throwing a set on my 03 yz250  as soon as possible. Should be hilarious in that, with a little work my steel frame bike will be just as good as 2013 yz250, and this engine hasn't been detuned haha.

[Stusmoke]

That KTMs 2t are the 'high end' of (relatively) volume production 2ts, shows how stagnant 2ts have become.

They (the engine modules) are pretty much the same vintage as the YZs. You can't regard a 250 /300 engine module that can have a 380 top end and crank, with little modification (crank end / one crank bearing?) required, a hugely different one to that of the 360 /380.  Yes, they slimmed / shrunk it down, dropped some weight, and did detail changes, but nothing like what KTM did with their 4t engines. Count up how many 4t engine types, just in the Dirt bike side of things, that KTM have made (include the 2 'Berg engines - the 'all in', vertically split unit , and the sloper).

It's been a result of rules that favour 4ts - capacity- and the subsequent loss of "competition", for KTMs 2ts.

Things are changing, finally, with new 2ts being produced. Though, they are not earth shattering technical innovations - pretty much just slightly refined 2ts - if that. But, they Will provide some competition, so they will, I believe, start to push development further. KTM will have to stop sitting back and raking in the dollars so easily, with regards to their 2ts. Finally. A Good Thing for All 2t enthusiasts.

"Competition", does that. The Beta, and the Sherco, are a great re-start of competition, within 2t ranks. A heck of a lot more-so than the Ossa, as they have gone into the Enduro market, before Ossa, and, they are bigger /stronger companies. Though, quite small compared to KTM, of course.

The  much, and justly, revered (and quite old aged) SSS suspension, deserves it's reputation - it works very, very well. Still above the std , latest model WP units - and that's coming from a bloke that uses WP CC front forks (though, much modified / set up for my uses).

Good post. Like you said, almost all the competition is in the enduro range, so even if KTM only faces competition there, whatever the advance on the enduro models are bound to be applied to thge MX range too. I'm no engineer, and this is just an assumption, but I would estimate that if Yamaha threw into their YZ range the same stuff the KTM comes stock with and revised their expansion chamber, it would undoubtedly give the KTM a run for its money in terms of power.

It is interesting to muse on what might have been if the AMA had a spine from day one and left hte rules at equal displacement. 250Fs would have had no advantage over their 250 smokers (besides being easier to ride). No advantage, no sales, no sales, no foopers. The big five would have still hacked away at their two stroke development 

I want a time machine.

[evo550]

I'm scratching my head, all I hear is "stagnating", "nothing revolutionary", "no earth shattering technology"
WTF does that mean ? It's a 2t motor- fuel comes into crank- goes to combustion chamber- fires-bike moves forward, seems to me the designers got it fairly well sorted out years ago.
You blokes seem to be obsessed with power and nothing else...go buy a 500. Suspension and chassis technology has lagged behind for years and now the factories have been focusing on that.
Bike and rider go faster when motor/chassis/suspension all work in unison, big horsepower will get you nowhere but pain.
Someone please explain what revolutionary/earth shattering technology you want?

[factoryX]

Ah, right now modern two stroke tech would boost power/efficiency output by more than 10-50%. By Stagnated, he means the only thing different from an water cooled 82 yz250 pv is 5-8hp, and that's probably carb related. Here is a brain twist, a yz250 piston bolts into a 1985-86 250r with a cylinder spacer boosting displacement to 265cc. That by definition is stagnation. I maybe wrong, but apparently some people were getting close with 250sx pistons as well.

Suspension alone isn't going to save the two stroke or simply allow it to race fairly against 4 stroke handicaps. This is beyond that.

Things that will help
1. Modern Porting as mentioned here and other threads.
2. Fuel delivery be it DI or Smart carb.
3. Pistons, although square stroke is very reliable, For racing purposes its approaching useless. For instance [2013 yz250 bore x stroke: 66.4mm x 72mm] [2013 250f bore x stroke: 77mm x 53.6mm!!!]
3. Modern material, two strokes can be made so much lighter its insulting. It maybe expensive to do it yourself, but from a mass production stand point....
4. Modern suspension, SSS is currently the best suspension ever put on a two stroke, that was 2006...
5. Modern Geometry, 4 stroke chassis have been updated for modern track layouts, the 2013 yz250 is running the same frame geometry as my steel framed 2003(Sub frames will bolt over no issues).

[Camstyn]

TM's electronic powervalve on the 125/144 is an innovation, it works off of RPM but has the capability to also use throttle position, which I'm sure they are doing a lot of testing with. That combined with Lectrons/smartcarbs could have a lot of potential for improvement.

[bearorso]

It's certainly stagnation.

What we have currently, are Engines that have not been developed at all appreciably - it's as simple as that.

Or, engines that have disappeared completely -  .

TMs Electronic PV - an innovation? Well, no; Electronic PVs have been around for a looooong time. I think Yamaha's YPVS - an electric servo motor driven PV, controlled through the CDI -  first came out on the 1983 RZ350 on a production road going motorcycle. In some markets it retained the RD prefix. Of course, combining E-PVs with the current levels of Electricery, would be a very useful thing. And, we await that on the TMs, as they have yet to incorporate TPS with their E-PV. I think the new Shercos have an E-PV? - though, I think I may have that mixed up with the Jotagas engine (not a Bimota, just a red Jotagas with Bimota branding - that was a useful way for Jotagas to get a lot of extra attention at EICMA. They used Bimota's 'cache' very, very well, they did).

Efficiency and Cleanliness, is the biggest benefit that can come from "modern" 2ts - but the extra torque / power, and, far more useful: a broader spread of power, that can be obtained with that increased efficiency, is a great thing. It will show  4ts to be an 'expensive', in more ways than just cost of production and purchase, power plant.

Modern Porting - well there's porting appropriate to the design of the engine / it's intended use.  Much like "modern Expansion Chambers", that are thrown around here.

Fuel delivery - yes, all sorts of designs can be used - then, of course there is the scavenging system - critically important on a 2t (well, any ICE)- and there are a lot of possibilities for that not used yet on 2t motorcycle engines.

Bore and stroke ratios - who knows what will happen? But, I'm bloody sure a 2t does not need to go anywhere near the extremes of Bore Vs Stroke that modern 4ts have gone to - as a 2t, of comparative capacity to a 4t, does not need to go in hunt of mega revs for power......... As I've written many a time - if you want to know about revs, and narrow power bands, just build a naturally aspirated 125cc single cylinder 4t to go up against a 125cc 2t. Go on Honda - 4ts are just so bloody good you can do it, can't you?  I'm sure they could, but it would be a rather expensive and somewhat 'difficult' to ride bike.

Yes, if they can make a 250F, the same weight as a 2502t, well, think of the weight you could make a 250 2t. Though, in the interests of ever getting equivalency in AMA Pro Racing, or the MXGPs - we might just have to stick with the same minimum weight rules a 250 4t and 250 2t currently have - the same weight (212 / 212.5lbs, in AMA Pro?) as each other.

SSS, is no disadvantage to Anything else currently on a production bike.

Modern Geometry? There's Nothing wrong with the 2005 / 2013 YZ250 Frame geometry, nor a last model(s) RM, CR 250. KXs, well.... Though, with the YZ250 05/13,  you can save a few lbs of ( a significant amount, but, of course, not all, being unsprung, which is an extra bonus) weight by fitting a 'near era' Yamaha 4ts swingarm, linkage and the rear wheel / hub. That just backs up the weight reduction efforts put into 4ts.......

Geezus, idiots wank on about last model (I think it covers about 11 model years, well, 13 if you count my 2003 compliance CRE500) steel frame CR500s having ancient geometry - the reality is, it has quicker geometry than last model aluminium 125 CRs, to my recollection. The crap written / spread about has No End, when it comes to "modern geometry".  A mate of mine that put a YZ250 engine into the latest YZ250F chassis, summed it up as a waste of ****ing time, other than the "Ooo Ahh" factor. Or, if you had a worn out / trashed 05/13 YZ chassis. His words, not mine. Some bikes have pushed the shock down lower, to compensate for the height of the 4t engines, so it's a useful change, but, with a twin spar frame, as the vast majority of bikes now have, you tend to be stuck with the tank, above the engine - and in a 2ts case, with a AF conversion, the weight often well above the engine. Put a big tank on, and it can be a Lot of fuel well above the 2t engine. Great idea....... I think not.

[evo550]

KTM have just recalled all their 2t throttle assemblies and will be retro fitting the 2012 and earlier set up.
They aren't stagnating....they're going backwards.
Someone should let Charles know to forget running KTM's on his TSM race effort, a '82 YZ 250 J will do just fine.

[factoryX]

4 stroke geometry and 2 stroke geometry are two different things as well as suspension set up for 4 strokes. MXA tested a 2012 service honda 250af, and it over powered the stock suspension valving. And how would we know if they could be made better? That last major update geometry wise for the yz250 was 03! They kept the geo when they went to the 05-up aluminum frame. I never said the SSS was bad, but new stuff is being released. I'm simply tossing ideas into the pot that might better the two stroke in general. If they did so well then even with ridiculous rules set against them, why are we in our current predicament? Things need to change whether it be rules(Good luck) or the bikes in general. Throttle assembly failure isn't what I would describe as a step backwards, its a $10-$20 part..

[evo550]

Throttle assembly failure isn't what I would describe as a step backwards, its a $10-$20 part..

Not where I come from, last time I priced a domino throttle assembly, it was near 100 big ones...

"a yz250 piston bolts into a 1985-86 250r with a cylinder spacer boosting displacement to 265cc."

What did you mean by this? Was it a CR250R ?

[2T Institute]

Things that will help
1. Modern Porting as mentioned here and other threads.
2. Fuel delivery be it DI or Smart carb.
3. Pistons, although square stroke is very reliable, For racing purposes its approaching useless. For instance [2013 yz250 bore x stroke: 66.4mm x 72mm] [2013 250f bore x stroke: 77mm x 53.6mm!!!]
3. Modern material, two strokes can be made so much lighter its insulting. It maybe expensive to do it yourself, but from a mass production stand point....
4. Modern suspension, SSS is currently the best suspension ever put on a two stroke, that was 2006...
5. Modern Geometry, 4 stroke chassis have been updated for modern track layouts, the 2013 yz250 is running the same frame geometry as my steel framed 2003(Sub frames will bolt over no issues).

A 50% power increase woul be impossible without a RPM ceiling increase.

1. Port layout is a small part of the equation the ducts have to be correct as well, no time for a cylinder reeds. Either case reeds or disc valves.
2. Apart from Uniflows bikes where are all the EFI bikes running round?
3. A 4T uses over square dimensions for a different reason and that is for rpm and to allow bigger valves for better breathing. The 68X68 YZ250 found more favour with kart racers than it did with MX riders. MX 250's are universaly 66.4 x 72mm which has proved the best combination of torque and rpm limits.
4, Without the use of  magnesium there isn't much mass to be stripped from a 250. If you used magnesium hugs and cases saving a few kg's, they would be practicaly useless after a few years. No manufacturer could cope with that.

[ford832]

It's certainly stagnation.

What we have currently, are Engines that have not been developed at all appreciably - it's as simple as that.

Or, engines that have disappeared completely -  .

TMs Electronic PV - an innovation? Well, no; Electronic PVs have been around for a looooong time. I think Yamaha's YPVS - an electric servo motor driven PV, controlled through the CDI -  first came out on the 1983 RZ350 on a production road going motorcycle. In some markets it retained the RD prefix. Of course, combining E-PVs with the current levels of Electricery, would be a very useful thing. And, we await that on the TMs, as they have yet to incorporate TPS with their E-PV. I think the new Shercos have an E-PV? - though, I think I may have that mixed up with the Jotagas engine (not a Bimota, just a red Jotagas with Bimota branding - that was a useful way for Jotagas to get a lot of extra attention at EICMA. They used Bimota's 'cache' very, very well, they did).

Efficiency and Cleanliness, is the biggest benefit that can come from "modern" 2ts - but the extra torque / power, and, far more useful: a broader spread of power, that can be obtained with that increased efficiency, is a great thing. It will show  4ts to be an 'expensive', in more ways than just cost of production and purchase, power plant.

Modern Porting - well there's porting appropriate to the design of the engine / it's intended use.  Much like "modern Expansion Chambers", that are thrown around here.

Fuel delivery - yes, all sorts of designs can be used - then, of course there is the scavenging system - critically important on a 2t (well, any ICE)- and there are a lot of possibilities for that not used yet on 2t motorcycle engines.

Bore and stroke ratios - who knows what will happen? But, I'm bloody sure a 2t does not need to go anywhere near the extremes of Bore Vs Stroke that modern 4ts have gone to - as a 2t, of comparative capacity to a 4t, does not need to go in hunt of mega revs for power......... As I've written many a time - if you want to know about revs, and narrow power bands, just build a naturally aspirated 125cc single cylinder 4t to go up against a 125cc 2t. Go on Honda - 4ts are just so bloody good you can do it, can't you?  I'm sure they could, but it would be a rather expensive and somewhat 'difficult' to ride bike.

Yes, if they can make a 250F, the same weight as a 2502t, well, think of the weight you could make a 250 2t. Though, in the interests of ever getting equivalency in AMA Pro Racing, or the MXGPs - we might just have to stick with the same minimum weight rules a 250 4t and 250 2t currently have - the same weight (212 / 212.5lbs, in AMA Pro?) as each other.

SSS, is no disadvantage to Anything else currently on a production bike.

Modern Geometry? There's Nothing wrong with the 2005 / 2013 YZ250 Frame geometry, nor a last model(s) RM, CR 250. KXs, well.... Though, with the YZ250 05/13,  you can save a few lbs of ( a significant amount, but, of course, not all, being unsprung, which is an extra bonus) weight by fitting a 'near era' Yamaha 4ts swingarm, linkage and the rear wheel / hub. That just backs up the weight reduction efforts put into 4ts.......

Geezus, idiots wank on about last model (I think it covers about 11 model years, well, 13 if you count my 2003 compliance CRE500) steel frame CR500s having ancient geometry - the reality is, it has quicker geometry than last model aluminium 125 CRs, to my recollection. The crap written / spread about has No End, when it comes to "modern geometry".  A mate of mine that put a YZ250 engine into the latest YZ250F chassis, summed it up as a waste of ****ing time, other than the "Ooo Ahh" factor. Or, if you had a worn out / trashed 05/13 YZ chassis. His words, not mine. Some bikes have pushed the shock down lower, to compensate for the height of the 4t engines, so it's a useful change, but, with a twin spar frame, as the vast majority of bikes now have, you tend to be stuck with the tank, above the engine - and in a 2ts case, with a AF conversion, the weight often well above the engine. Put a big tank on, and it can be a Lot of fuel well above the 2t engine. Great idea....... I think not.

Great post bearorso,I couldn't have said it better myself-or near as well for that matter.
Some of you should read this carefully rather than just skimming it and going back to your original thoughts of equating new plastics with new 2t engine design.

In the end though,who cares about bikes at all when one has "dirty girls"   
Bring them along racer x,I'll take the redhead-or any other as well.

BTW,the KTM throttle part is worth exactly $0.00.KTM is replacing them foc.

Many of us remember fondly some of the old 2t machinery.When you go back and ride them again you're reminded most do indeed have a great engine.The second thought is always to wonder how I ever rode one of these in the first place as the suspension is truly awful.Of course,at the time,it seemed pretty good relative to what was out there-by todays standards-it's grim.
If you want to talk off road bike development(4t engines aside) look at the suspension side of things,that's where it is.

[factoryX]

Throttle assembly failure isn't what I would describe as a step backwards, its a $10-$20 part..

"a yz250 piston bolts into a 1985-86 250r with a cylinder spacer boosting displacement to 265cc."

What did you mean by this? Was it a CR250R ?

ATC/TRX250R Very similar motors to the 85-87 cr250 engines. I can't remember if you had to bore slightly or they simply bolted in, either way it works.

[nom de guerre]

Ford, you are just as crazy as the Maico nuts.....

[evo550]

Throttle assembly failure isn't what I would describe as a step backwards, its a $10-$20 part..

"a yz250 piston bolts into a 1985-86 250r with a cylinder spacer boosting displacement to 265cc."

What did you mean by this? Was it a CR250R ?

ATC/TRX250R Very similar motors to the 85-87 cr250 engines. I can't remember if you had to bore slightly or they simply bolted in, either way it works.

So where does the cylinder spacer go?