are 2 strokes being banned?

[Trashthumpy]

its commen sence 4 strokes require more maintanence than 2 strokes they have far more moving parts and components, and a WR is the same as the YZF just has lights, plates,zorst etc. and suspention set up a bit differntly.

 

[motoluver]

its commen sence 4 strokes require more maintanence than 2 strokes they have far more moving parts and components, and a WR is the same as the YZF just has lights, plates,zorst etc. and suspention set up a bit differntly.

Dont forget the gearing. The WR is setup for trails. The yzf is setup for mx. Not only do 4 strokes have more moving parts, they HAVE more parts then 2 strokes.

 

[Trashthumpy]

o yes and gearing....but the way 4 strokes are going their will be no market for 2 strokes anyways, i sold my yz125 and bought a yz250f and the power diffence is amazing! the 4 stroke just seems to keep pulling and pulling with amazing bottom end power,

 

[Cactus Jack]

Dont forget the gearing. The WR is setup for trails. The yzf is setup for mx. Not only do 4 strokes have more moving parts, they HAVE more parts then 2 strokes.

The WR has a lower 1st gear so that the bike will climb steep hills at low speeds and putter along trails , and a taller 5th to allow it to cruise roads and highways without screaming its' guts out and going too slow . The ratios in between are also spread further apart .

The YZF has a taller 1st gear and all the gears are closer together to keep the engine in the best power range all the time for the quickest possible acceleration during racing conditions .

4 strokes have more moving parts - but they are lubricated by thick oil so they don't wear very quickly whereas the 2 stroke is lubricated by a thin petrol/oil mix and they wear pretty quickly in comparison .

Drain the oil from your pit bike and fill it with 2 stroke mix then take it for a thrash and we'll see how long it lasts - then you'll get the drift .

The main reason for the maintenance on four strokes is purely because they took the lead out of fuel which is what valves , upper bores and top rings rely on for lubrication . The lead virtually eliminates valve wear and valve seat recession . IF you ran your engine on leaded fuel - you'd rarely have to adjust valve clearances . Formula 1 cars run ELF high octane fuel - ELF stands for Extra Leaded Fuel in case anyone didn't know . They run the leaded fuel because they wouldn't finish a single race running on unleaded .

Anyone who isn't running a lead replacement such as tin , valve saver or castor oil in the fuel on their four stroke is a fool . Lead also reduces detonation - the main cause of four stroke blow ups and engine damage .

Car and road bike engines are four stroke and they turn over billions of revs for years over thousands of miles without needing constant rebuilds . The YZF cylinder is simply a cylinder off a YZF 4 cylinder road bike engine so WHY would they wear out quicker in a dirt bike when they can be revved for miles and miles , hour upon hour , month in , month out for years in road use ?????

What dork brains have to realise is that you can't run a water cooled engine revving its ass off at low speeds around a track - radiators require high AIRFLOW thru them to cool the engine .

Most dirt engines that have had problems will be getting damaged by detonation from over heating from being ridden at too low a speed . The only other thing that could cause damage and wear is lack of regular oil changes and dirty air filters .

Excess heat from continual slow riding , dirt and mud blocking the radiators would cause the oil to go bad faster . Water cooled street engines have thermo fans which kick in when the vehicle is going too slow for the air speed to provide adequate cooling . So WATER cooled dirt bikes without thermo fans should purely and simply NOT be ridden slow - doing donuts etc . Water cooled 4 stroke MX bikes are designed to be ridden fast and they need to be kept moving at a decent speed to stay cool . Flog one around your back yard or small local track for any decent length of time and you'll blow it up in next to no time at all . Air cooled bikes on the other hand can be ridden at slow speeds in filthy heat ALL day long - your local posty bike is concrete proof of that - and pit bike engines which are ridden harder have increased cylinder fin sizes and can be fitted with oil coolers to get rid of the extra heat . I'd just LOVE to see someone try to deliver letters all day in the middle of summer on ANY water cooled bike ~ without having electric fans blasting away at the radiators .

2 strokes get away with it because they pull their intake air thru the crank case and that's similar to being fan cooled ! IF you ride slow - stick to air cooled 4 strokes like XR's - they last for donkeys years with the minimum of maintenance .

 

[cass38a]

Car and road bike engines are four stroke and they turn over billions of revs for years over thousands of miles without needing constant rebuilds . The YZF cylinder is simply a cylinder off a YZF 4 cylinder road bike engine so WHY would they wear out quicker in a dirt bike when they can be revved for miles and miles , hour upon hour , month in , month out for years in road use ?????

You are correct however their is one point that you didnt make which is the riding conditions between a road and MX bike. One is ridden on sealed roads uaually within the speed limit and in sensible rev ranges. The other usually has its arse flogged out at max revs in dusty contitions which can make a difference.

 

[Ruby]

is it just me or has ruby had a 'fight' 2 people on here already lol

I disagree with motoluver, he disagrees with me. I hardly call that a fight. There's been no name calling, so its been quite civil. This is just a broad topic based on opinions and mountains of variables to argue those opinions. Thats all.

I'd be more than happy to share a beer with him and discuss this over the table. Over the forum, people get the wrong impression and the situation blows out of proportion, because everyone things everyone else is having a go at them. Hence, why I said I was finished with debating the point.

Cheers.

 

[yelloww proX]

i looked at it from the other point of view sorry, and yes this is a very broad topic, its its been a great ******* read 4 me... lerent so much more about 2 and 4 stroke engines.. i mean who need skool jsut stick to a forum all day and ur sweet lol

 

[Ruby]

Yes, the arguments have been tops from both sides of the fence.

 

[Cactus Jack]

o yes and gearing....but the way 4 strokes are going their will be no market for 2 strokes anyways, i sold my yz125 and bought a yz250f and the power diffence is amazing! the 4 stroke just seems to keep pulling and pulling with amazing bottom end power,

Here's something to think about :

Some people have it in their heads that the 4 strokes are twice the sized motor and unfair .

125 cc two stroke means that the engine burns 125 cc capacity every 2 piston strokes which adds up to equal 250 cc burnt every 4 piston strokes .

250 cc 4 stroke means that the engine burns 250 cc capacity every 4 piston strokes .

A YZ250F is the precise equivalent of a 125 cc two stroke engine .. 250/4 = 125/2 - check it out on a calculator .

Looking at both engines @ 10,000 rpm we get :

A 2 stroke fires EVERY single rpm . 2 piston strokes = 1 crank rev (1rpm)

YZ125 = 125 cc x 10,000 power pulses per minute @ 10,000 rpm = 1,250,000 cc burnt per minute .

A 4 stroke fires every SECOND rpm . 4 piston strokes = 2 crank revs (2rpm)

YZ250F = 250 cc x 5,000 power pulses per minute @ 10,000 rpm = 1,250,000 cc burnt per minute .

So BOTH engines are precisely the same capacity while they are running at the same engine speed - most people only look at the static bore size - but engines don't sit still do they !

4 stroke engines make far better use of their cc capacity at all revs just as you have found out . 2 strokes are inefficient down low then they start making power up top like the RACE DEVELOPED 4 stroke and that accounts for their "powerband" hit . People used to compare a stock XR80 trail bike motor to an 80 cc 2 stroke MX race bike and THINK they knew everything about 4 strokes . But NOW the manufacturers have finally admitted that a 125/2 stroke equals a 250/4 stroke and everyone has had their heads turned a complete 360 degrees .

And using the above formulas - I don't have to tell you that allowing 2 strokes to be 144 cc against 250F's is NOTHING more than an invalid pensioners concession for the poor old underpowered 2 strokes !

 

[Meko]

Wow Cactus, thats a really interesting collection of stuff to think about & has totally changed my understanding of 2 & 4 stroke motors. It makes alot of sense too. Thanks for explaining it all, I'm sure other members will gain alot more insight with your post,

 

[Divy]

yeah thanks cactus cause on a old thread ppl were saying my 125cc 2stroke was a kids toy and a 250cc 4stroke will eat my bike

and i was trying to say the 125 2stroke is just as quick as a 250 4stroke
i knew the different burn cycles but you explained it perfectly

oh im not saying the 125cc 2strokes are the best im just glad he explianed that more cc's dont allways mean quiker

 

[motoluver]

Imo a 125 would compare to a 250f if they didnt have as much wheelspin where as the 4 strokes just want to grip. 250 2t are a little better as they have plenty of bottom end power but still if they didnt have as much wheel spin they would compare to a 450f.

 

[Cactus Jack]

Imo a 125 would compare to a 250f if they didnt have as much wheelspin where as the 4 strokes just want to grip. 250 2t are a little better as they have plenty of bottom end power but still if they didnt have as much wheel spin they would compare to a 450f.

2 strokes drive the crank every time it comes to top dead center whereas 4 strokes only drive their crank every SECOND time it comes to top dead centre . The bigger gap between the power pulses allows the tyre of the 4 stroke bike to get a chance to grip and get far better traction . You can also adjust and control the torque of a 4 stroke to the rear wheel better by making it lug a taller gear to maintain better traction - without losing acceleration.

Diesel locomotives that use DC (direct current) traction motors which put constant drive on the wheels ~ suffer from wheel spin and traction loss .

The engineers discovered that the same diesel loco could pull up to 30 % more load if it had AC (alternating current) traction motors which give intermittent drive to the wheels . The break in drive as the current alternates , allows the wheels to gain better traction and makes the same HP locomotive far more efficient at pulling more weight .

ABS brakes work the same way - they grip the disc and back off in rapid succession (pulse) - allowing the wheels to maintain far better grip under braking to pull the vehicle up quicker than standard brakes which grip too hard and lock the wheels up .

Another factor as to why 2 strokes have trouble getting traction is that the expansion chamber is really a hidden TURBOCHARGER that uses sonic pressure waves to effectively SUPERCHARGE the cylinder way above what is normally possible . The fact that they are supercharged when they're "on the pipe" is really what the "powerband" surge is all about .

Put a turbocharger on a 4 stroke and you'll also find it to be a bitch to handle and control as the turbo boost kicks in .

Howstuffworks "Why is there a bulge in the exhaust pipe of my dirt bike?"

Le Espansioni

Add the turbo boost to the fact that 2 strokes burn the same capacity at the same rpm as a 4 stroke with twice the static bore capacity , and you'll understand why they have such a strong kick to them - they should make a HEAP more power than even double the capacity 4 stroke but they lose a ton of power due to friction attributed to their poor lubrication method .

Doubt that the 2 strokes are supercharged ? Then explain how an XR80 only makes around 5 HP - yet a CR80 - 85 makes around 20 HP - about 4 times the HP output ! A KX 60 makes 16 HP (stock) - yet you have to work the frigger out of a 140 to 160 cc horizontal 4 stroke or build an F1 spec 4 stroke to get similar power ! The ONLY way you'd get 16 HP out of a 60 cc 4 stroke is to put a turbocharger or supercharger on it set up to give a super high boost level .

I see all this and the word BS cheating by the 2 strokes in the past comes to mind !

I wonder if the 2 stroke racers would play fair (give up expansion chambers) and run a straight exhaust like a 4 stroke . 2 strokes don't need to run an expansion chamber - out boards , whipper snippers , chainsaws and mowers prove that . Then they could be allowed to run a bigger bore size and STILL get flogged by the 4 strokes - just like how it used to be before expansion chambers were put on MX bikes .

 

[Cactus Jack]

I forgot to mention that reed valves and crankcase induction also allow the crankcase to be used and as positive displacement pump (aka SUPERCHARGER) to FORCE pressurized fuel/air charge into the cylinder from the intake side . 4 strokes rely totally on vacuum and normal atmospheric pressure to fill their cylinders from the intake side ONLY . 2 strokes get blown via the front door as well as thru the back door !

Crank case reed induction in 2 stroke engines has the same effect as a 4 stroke engine getting force fed by a rootes type mechanical supercharger !

 

[Trashthumpy]

Here's something to think about :

Some people have it in their heads that the 4 strokes are twice the sized motor and unfair .

125 cc two stroke means that the engine burns 125 cc capacity every 2 piston strokes which adds up to equal 250 cc burnt every 4 piston strokes .

250 cc 4 stroke means that the engine burns 250 cc capacity every 4 piston strokes .

A YZ250F is the precise equivalent of a 125 cc two stroke engine .. 250/4 = 125/2 - check it out on a calculator .

Looking at both engines @ 10,000 rpm we get :

A 2 stroke fires EVERY single rpm . 2 piston strokes = 1 crank rev (1rpm)

YZ125 = 125 cc x 10,000 power pulses per minute @ 10,000 rpm = 1,250,000 cc burnt per minute .

A 4 stroke fires every SECOND rpm . 4 piston strokes = 2 crank revs (2rpm)

YZ250F = 250 cc x 5,000 power pulses per minute @ 10,000 rpm = 1,250,000 cc burnt per minute .

So BOTH engines are precisely the same capacity while they are running at the same engine speed - most people only look at the static bore size - but engines don't sit still do they !

4 stroke engines make far better use of their cc capacity at all revs just as you have found out . 2 strokes are inefficient down low then they start making power up top like the RACE DEVELOPED 4 stroke and that accounts for their "powerband" hit . People used to compare a stock XR80 trail bike motor to an 80 cc 2 stroke MX race bike and THINK they knew everything about 4 strokes . But NOW the manufacturers have finally admitted that a 125/2 stroke equals a 250/4 stroke and everyone has had their heads turned a complete 360 degrees .

And using the above formulas - I don't have to tell you that allowing 2 strokes to be 144 cc against 250F's is NOTHING more than an invalid pensioners concession for the poor old underpowered 2 strokes !

thanks for posting that up mate it has realy made me understand how the power differences work! cheers

 

[Cactus Jack]

Are two strokes being banned ?

The main thing to think about that is really relevant to the theme of the thread is :

- Where all that info above works against the 2 stroke is when you submit two engines to the EPA as both rated as the same capacity ~ the same sized engines ~ and the EPA tests them both and says "piss off with that 250 cc 2 stroke , and bring it back when it puts out the same emissions levels as a 250 cc fourstroke " .

That means that even IF an 80 two stroke was submitted as an 80 cc engine running on pure unleaded fuel with no oil burning in it - it would STILL be pumping out over twice the volume of emissions as say a CRF80 4 stroke or an 80 cc pit bike engine .

They can't and never will get them to the same levels as long as they are burning twice the cc capacity of fuel/air/oil mix as the same bore capacity 4 stroke on unleaded .

That's one of the reasons why they will definitely be phased out . The manufacturers should come clean and rate all engines using a common denominator !

It IS possible to get a 2 stroke to run heaps cleaner than a 4 stroke on unleaded fuel - simply use LPG injection with NO oil injected with it ...........