2 stroke V's 4 Stroke- Lets thump it out??

[DJRacing]

So once again I ask, 2T V's 4T. Who made it this way? Do the younger MXers of the world like spending a lot more money? Is it the manufacturers pushing it because of the money they make from the servicing/rebuilds/after market parts? Is it the governing bodies of our sport? Enviromentalises'? Surely to invite more people into a sport the governing bodies would want to keep the cost as small as possible, encourage more competitors? So are the riders getting the rough end of the stick or do they not know any better? Or is it that the marketing men aint allowed to advertise 2T as 'the most powerful, exciting, vibrating piece of machinery ya can have between ya legs' coz it would be seen as a sexist ploy to undermind lezbo's who cant ride motorbikes? Heaven knows what the reasoning is behind it all but at least they should make the classes equal pegging.

[pokey]

For a most obvious reasonwhy the world has gone 4T look to the largest market and see what has changed. The US of A is undeniably the largest  market for bikes and  we also find California anti pollution laws extremely stringent  on the 2T engine. I believe it states oil cannot  be addesd to a fuel  or somethong like that which even though no  visible smoke  even the finest metering of lubrication is seen as illegal as its deliberately added .. yeah the law is an ass.

[Anthony.522]

Who knows? The 2 strokes always made good power, no ones disputing that, If they can make a 2 stroke that rides like my 450 or 250 i.e torque across the board, not overly agressive etc, I think racers will look in to them but untill then not many people are going to touch them. Can you imagine a 50kg rider trying to hold on to a CR250 for 20 minutes, he's got no chance. Electronic controlled power valve like on the CR's? Yeah cool but didnt the Yamaha DT have that ages ago? so thats nothing new. You mention all these things that can be done to them.... why werent they? They were making 2 stroke race bikes for say 35 odd years, what were they waiting for? I'm sure engineers would have known a while ago if you did this and this to the ports you would get that. All these things that could have been done to improve them and make them more efficient, less pollutive etc, i'm sure they figured this out alot longer then a few years ago, there was a reason why they went the other way,  people will pay the money, I could probably save alot racing a 2 stroke but i'm not going to do anyting that dumb, the way my bike goes i'm quiete happy chucking valves and oil filters at it and so are alot of people.It's like mud you whinge about it for a bit but you just get on with it.

[AjayVMX]

I think the manufacturers initally supported the change to 4 strokes because:

a) No-one had them, so everyone had to get a new bike.
b) The higher maintenance requirements would mean more revenue through spares replacements (remember that the factories don't make much money on the intial sale anyway).

However, I think that it backfired on them because they didn't realise that the increase in running costs would be so dramatic - sure they have made money hand over fist for awhile now, but now there's a lot of pissed off and broke customers out there who have possibly given riding away due to the cost. (as witnessed by the sudden and considerable reduction in sales in the USA this year).

I also think the aftermarket companies, especially those that peddle the extra loud powerpipes for these beasts will reap the whirlwind shortly as well.  Noise will undoubtedly cause more and more land closures.

At least some manufacturers are getting the message - Kawasaki is a case in point.  The new KLX450 not only has steel valves for longevity, but apparently the bike is whisper quiet while still being damn fast.  If that is the future for 4 strokes, then it will be a good one indeed!   (so long as the thong nongs don't replace with pipe with something louder of course... :'( )

[Anthony.522]

I think the drop in sales may be due to all the bikes not being majoryly updated, by that i mean most of the fleet in the 07 range are pretty much the same as the 06 range with some improvements here and there. It will be the same again for the 08's except for suzuki with the efi. Maybe some people couldnt justify the upgrade? It could be a factor. I think the industry has realised there is a sound problem all the factory jap race bikes are at 96db, and most aftermarket pipes are starting to comply with it offering 96 and 98 db pipes. It has to change or we are going to loose alot of tracks     We'll see how well the steel valves go, as Steve from Cisco's explained it to me a while ago, on the titanium valves they start to go when the coating on them goes, you can get around this, yes you can use the stainless valves which are stronger but they pound the valve seat more and wear that.

[vmx42]

Hi Ajay,
Yeah Kawasaki has done the responsible thing - created a quite 4 stroke that actually runs well without modification, straight from the showroom floor.

I can guarantee you one thing though - as soon as the magazines get hold of the KLX, the first thing they will do is replace the pipe with one that is louder.

How they can preach the benefits of a pipe that costs [in Aust] up to 10% of the original cost of the bike, reduces the weight by 0.5% [if you are lucky, and remember that the KLX is a bit of a porker], makes maybe 2% more power - BUT doubles or quadruples the NOISE LEVEL [remember decibels are logarithmic] when new [I can't imagine how much noiser they are when they need of repacking].

Boy that sounds like value for money!!!!!!!

If I was in the market for a new MXer  I would buy a 2-stroke just to be different [while I still can].

VMX42

[AjayVMX]

Yeah, my bottom line was (when I was still riding):  Ride a 2 stroke until they aren't available anymore....

Although if I was able to ride the KLX450 would be tempting 

[DJRacing]

Anthony, why couldnt I imagine a 50kg rider on a CR250? I would think a 50kg rider on a CRF450 would be more of a problem. A 2T can be made to have more torque by adding weight to the flywheel. Correct me if I'm wrong(it has been know to happen) but isnt racing, be it boats,cars,trucks and motorbikes,(esspecially motoX) all about who can keep it wide open the longest, which is generally past the point of torque? The funny thing about a 2T is that once in the powerband, the power delivery is generally smooth, its only when you drop out off the power when it becomes agressive. Now, I think 4T are great bikes(as I say I have one) but cc for cc is what racing should be about. About the pollution thing, who gives a rats ass when its about racing? Does Corperate/Government people when one of them jumps into a limo, drives to the airport and hirers a plane for themselves to fly around the countryside.

[pokey]

Only thing I ever liked about trail riding a 4T was not having to refuel   to get home. yes they were quiet unlike the new breed of 4T bikes and that is of a concern . Many tracks are being closed because they are too close to urban development and  the shrill pipes on a new 4T is not going to endear them  to anyone. Can you imagine anyone allowing  racing with  no silencers on a 2T ?

 Frankly couldnt give a damn what the current manufacturers  choose to use as a power plant as im firmly rooted in old 2T bikes. Bikes with character that you need to be able to learn to ride , that didnt do it all for you. Learn where your power comes on at and pick the line and the right gear and grab the correct amount of right hand, slip the clutch  and slide the rear.... May aswell buy an automatic Hyundai or catch a bus if you want it all done for you.

Will be good to see the results of the afore mentioned  race. If its a tight track  my beer money will be on the 2T slapping the 4T something chronic.. lighter and faster off the mark.

RD 400
TZ 750
H1 750
 Now those bikes were adrenaline machines and thats fun  and after all isnt fun what bikes are all about no matter how many strokes they be?

[Lozza]

Anthony, sadly you seem not to understand what is being said, DT's have an electricaly controlled powervalve by a servo,electrionic control intercepts the standard control and then youcontrol the opening and closing of the valve.Standard open/close powervalve curves are shit and have an on/off operation giving an (surprise surprise)on/off style of power delivery.When electronics are involved the result is more bottom end and top end over rev.An overall smoother power that can be altered to the conditions.Bit the same as variable cam timing.....any 4 bangers got that these days? Exactly the same with an ignition.Fact is they are being done right now and all it takes is a 1kg 12v battery and anyone can have one

[Tim754]

Yep fair comment Pokey,,, But put the piston port reed valved RD400  or even an LC350 up against an electric servo assisted power valve RZ350, no contest. RZ miles better to ride in all respects in my opinion and still had 2stroke character. Why servos where not put on all two stroke power valves I don't understand. As Lozza states only a small battery to power the electronics, Hey who objects to electric starters with there batteries on modern MX and trailies...........Tim

[pokey]

Too True Tim. The RZ is a way more refined  bike than those nasty  but fun dinasaurs, even handled  reasonable  comparitively.

 Piston port
 Rotary valves
 Reed valves
 Power valves

Most of that tech is circa 1900 and just look at the advances and variables that have been made and still being made using  the basic principles of port angle and placement. There is yet to be found a fomula that is considered the ultimate  for a 2T engine as well all need to dial on the speed and torque at different times for different tracks conditions and riding styles. same with a 4T, they also need to be tuned  to bring the power on  depending on the task at hand to get the best from that engine. Engines frames suspension  tyres  its all black magic and constant tinkering.

 God help us if we are reduced to smooth power titanium monocoque "electric" MX bikes. Not sure I'd ever part with dollars for a Hoover or Electrolux 250 watt Plug N Go or a turbo charged  Biofuel diesel MXer no matter how many flash stickers it had or how the exhaust smell reminded you of fish N chips.. Still be like  riding in a postie bike race. Kind of takes all the challenge and fun out of it.

 

With technology comes refinement and engine advancement depends where the big boys.. and the lobby groups wish to go as to where the research dollars will go, thus determinining the future if any of off or on road bike racing. Dont  dismiss the 2T just yet guys. a lot of life  yet to be unveiled with that style of engine.

[Lozza]

True pokey,the yoof will find out that the next 'must have' item for the efi'd dirt bike is the 'Power Commander' they will of course be about a grand lighter(after the dyno time) but there is about 3kw all through the range. Still reckon that's better than stickers.........Ah who remembers the rolls of 'contact' and tracing adverts from magazines

[Freakshow]

yes for some reason though it would always have to many "C"'s, i think i keep cutting into the "O"s

[Nathan S]

For a most obvious reasonwhy the world has gone 4T look to the largest market and see what has changed. The US of A is undeniably the largest  market for bikes and  we also find California anti pollution laws extremely stringent  on the 2T engine. I believe it states oil cannot  be addesd to a fuel  or somethong like that which even though no  visible smoke  even the finest metering of lubrication is seen as illegal as its deliberately added .. yeah the law is an ass.

That was the law. It's what killed the RX-7 in the USA (they run a very limited amount of engine oil into the combusion chamber in a system very similar to a 2-stroke auto-lube set-up).
Stupid thing was, they burned less oil than a heap of conventional four-stroke engines (*cough*Chev Gen3*cough*), but the laws simply said that you can't deliberately add oil into the combustion chamber.

However, I'm guessing that the law must have changed, because the RX-8 is sold in all USA states, despite having a similar oil injection set-up to the RX-7.

I agree with VMX42's post in the other thread - the rules should set the levels and leave the 'how' up to the manufacturers.


Anyhow, I'm half-heartedly trying to work out whether you can fit a DT230 engine into a newish YZ125 chassis, with programable electronics (inc EFI, eventually). I reckon you'd easily get with most/all of the conveniences, power and tractability of the newer 450 4-strokes, in a bike that would be far less maintenance intensive, more reliable and lighter.