I got to ride one today, but it didn't impress me. The owner thinks it's a beast, I say I can turn better laps on my smoker. The power was OK, but I still needed to clutch it (owner recommendation) . Also, the start procedure sucked, it took too long. "Pull this knob, push the kicker down, let it up, pull this lever, push the kicker down a little, let it up, release the lever, grab the crossbar, give it a kick, push that knob back in." Sorry, I'll pass, but in the bikes defense, it was a YZ426 with a suspension that was way too stiff for me. I do now understand why the AMA upped the displacement advantage.Okiewan said:How much time do you have on a 4-T? No, not surfing the web time, actually time.
those bikes are in a completely different class, they are trailbikes. this discussion is about motocross bikes, the technology is completely different.mxrider76 said:I have had a xr 80 for four years. One topend. I ride all I can(almost every weekend) pour gas in it and check the oil. Same with my suzuki dr 125 check the oil and filter oil the chain pour in gas and hit the electric start and off I go.
AJ Waggoner said::::::::rant on::::::::
...as for my personal rant in this thread, lets all please recognize that emiissions are not the reason for the decline of 2 strokes...
...but you cant ignore the fact that those huge R&D dollars could have been thrown at the current 2 strokes and with all the Ti componentry and all the trick engineering,
some amazing bikes be put out as well?....
::rant off::
RADRick said:With no end user application other than closed-course racing, what purpose is there in developing a cleaner 2-stroke engine? Factories race for one reason, to develop products they can market and sell profitably. 4T technology is the dominant force in auto and motorcycle design, both street and off-road. Why pour money into a technology that has such limited application?
RADRick said:A 2-stroke has a power stroke on every revolution of the crankshaft. A 4-stroke has a power stroke on every other revolution of the crankshaft. Despite the seeming advantage of displacement of a 450 4T over a 250 2T, the 250 actually does more work at the same rpm making it equally as powerful. The 4-stroke gains a torque advantage because of the extra displacement, but that isn't necessarily a performance advantage. Think of it this way: for every 1000 rpm a 4-stroke puts out only 500 power strokes. A 2-stroke will put out twice as many power strokes. ..... Since the 4-stroke also has a valvetrain to deal with, much of the power advantage gained by the larger displacement is used on turning the cam and chain and overcoming the resistance from the valve lifters, springs, much heavier flywheels and higher combustion chamber compression. To stay properly lubricated the 4-stroke must also use some of its power to turn an oil pump. A 2-stroke has no valvetrain or oil pump to rob power and it has less cylinder compression and lighter flywheels to overcome so that more of its power is going to the rear wheel. There's also the added weight of a 4-stroke. When compared solely by output....
The fact remains that the 2T, even if it could be made clean enough to pass emissions (which I doubt), would not have the broad appeal that the latest 4T models have. There are many riders like myself who got back into the sport solely because of the newer 4-strokes. Having given up racing long ago I wanted something that was easier and more fun to ride with less chance of injury. Many riders I come in contact with say the same thing. These new 4T bikes have extended their riding while still giving them the performance they want. Racing isn't everything to the vast majority of riders. The balance was tipped because the 4T provides manufacturers more sales potential, not just because of any emissions regulations or sanctioning body moves. Dirt biking is exploding in popularity, and not just because it is getting more TV coverage. The newer 4-stroke models are helping to bring new riders into and old ones back to the sport. Riders who likely might not have if 4-stroke technology had not developed to where it is today.BRush said:Well, to win races and sell motorcycles would be one very good reason. Winning is a powerful marketing advantage. I agree with you about 4T technology being where the R&D money is being spent today. Why is that? Back in the day, four strokes were not competitive with two strokes of equal displacement. The rules were tweaked to address that imbalance, basically by handicapping the two stroke and tipping the scales in the other direction in order to encourage 4T development. If those changes had not been made, it is quite likely that two strokes would still rule the racing scene today. Why? You said it yourself:
Those tech advantages are still there for clever engineers to exploit. And if two strokes cleared the emissions hurdle and came to dominate the racing scene again, the market would follow.
just_a_rider said:4t's aren't made to turn the rpm's of 2t's although some think so and you can hear them cutting out over jumps being over reved thus streaching the valves causing premature valve adjustments. You can get a valve job around here for about 30 to 40 bucks. QUOTE]
:coocoo: :blah: :blah:
Jeeze! Where do these guys come from? :whoa:
RADRick said:In a world where perception is everything, fewer people seeing a smokey tailpipe running through the woods or on a racetrack is a good thing. We can lament the demise of the 2T all we want, but at the end of the day it will likely do more to further our sport than sticking with the technology would have.
motometal said:The powervalve, by nature, leads a much, much easier life than valves on a 4-t, which are hammering open and shut thousands of times per minute.
Most riders will use the oil they know or see being used by others. It's probably too late to educate them on the alternatives.motometal said:Smokeless oil and/or proper jetting addresses the smoke issue.
I still have to disagree with you. Many non-riders never actually come close enough to a track or riding area to know what the noise issue is about, but they will see a photograph or televised event showing a smoky motorcycle and have it leave an indelible negative perception on them. I'm not saying noise isn't an important factor, but the smoke is very much a real issue. I've been to enough city council meetings for proposed parks and tracks to hear it voiced by the opposition.Your post didn't relate to the increasing noise problem...when's the last time you heard of a riding park shut down because of the smoke? I disagree with your point that the smoke is a "real" issue in the public's perception, especially in comparison to noise. What about all the busses, trains, and semi trucks belching out smoke...we'd better get rid of those too, right?
Well, I'd just say that we have differing opinions on this. I know a lot of older riders who are only still riding because of the current technology of 4T engines, myself included. I also know many former 2T riders who are very happy on their 4T bikes and have no desire to go back. Different strokes for different folks.Regarding the fours being so much easier to ride, yes and no. Depends on the circumstances. 450 vs 250 (2 stroke) for example, you can run a gear high on the 250 and the power is pretty tame, but the 450 has power right now, regardless. This is also related to the continuing popularity of the 2's for the woods, hare scrambles etc. Actually, easier to ride there. Sure, you can buy a "woods" four stroke, but now you have a detuned motor and extra weight that you don't need, compared the the 2-t.
You sound like someone who listens way too much to the Speed/OLN race announcers who can't let a moto go by without pointing out the vagaries of a stalled 4T. This may have been true back in 2001, but today's production 4T is much easier to start. Don't compare them to the highly tuned, race gas running bikes the pros are racing. They are so close to the limits of stoichemetry that a mere 5 degree change in ambient temperature can wreak havoc with them.Also, considering which tends to stall more frequently and which is easier to start, in my opinion this would actually be a turn-off if I was getting back into the sport after many years.
Increased maintenance to a 2T, perhaps, but by no means enough to drive a choice difference. As for "tricky starting procedures," are you kidding me? Besides the addition of an easily reached hot start lever and the need to get a complete stroke out of the kickstarter, what is trickier than the 2T? And changing the spark plug is a non-issue. A properly jetted 4T can go a whole season or more on a single plug. 2T plugs foul regularly and need easy access because of it. Yes, the 4T spark plug is a pain to get to, but it isn't likely to be something you need to do very often.It's hard for me to see increased maintenance, tricky starting proceedures, having to remove the fuel tank to change a spark plug, etc. as "marching forward" technology wise (although I know that in a backwards way, it is).
RADRick said:Don't compare them to the highly tuned, race gas running bikes the pros are racing. They are so close to the limits of stoichemetry that a mere 5 degree change in ambient temperature can wreak havoc with them.
As used, stoichemetry refers to the ratio of fuel to air for proper combustion in an ICE. That ratio is approximately 14:1 air to fuel. Stoichiometry is the reaction of chemicals in quantities and combination. Sorry if I threw you a curve ball.Rich Rohrich said:Did you honestly think you could post that without someone throwing the BS flag? :rotfl:
I'm wondering based on your usage if you even KNOW what stoichiometry means. :whoa:
...or
Maybe this just warrants further explanation on your part so we can all understand. ;)
RADRick said:As used, it refers to the ratio of fuel to air for proper combustion in an ICE. That ratio is approximately 14:1 air to fuel.
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