the 09 yz's

[tigmaster]

OK, we can argue this whole deal once again.

Well, sure direct injection is going to be nice. The only issue is that two stroke per combustion revolution are not anywhere near as efficient as four strokes. That is a fact proven with science. So that being said, direct injection is nowhere close to the step EFI made. Next point about DI. The fact is you are still just straight burning oil! The government is not too happy about directly burning oil so unless two strokes have some magic tricks to come, the government and whoever else has issues with them will have them gone. Just look at every lawn and garden tool now. There are only a few two stroke models left on the market and you know what?????? The four stroke items in lawn in garden boast about lower maintenance!!! When you aren't trying to squeeze 50hp from 450cc, you can make things a bit more durable.

Also, Kawasaki and Suzuki are not almost the same. They made one bike together that lasted a run of two years for Kawasaki and three for Suzuki.

Four strokes show obvious advantages and if you compare per combustion revolution, 4 strokes make more power because they are more efficient. Four strokes offer twice as many revisions from which to gain power as to two strokes. The issues is, four strokes have efficiency by a long shots over the twos and because of this, they can do crazy things like rev way higher than the twos mostly because they aren't restricted by crazy sonics issues and trying to evacuate exhaust gasses.

Like WR said. Four strokes were here first and twos are just a phase which we will soon grow out of. They had a good run and I loved owning one but you have to change with the times.

[BansheeRider]

how can you say that? is your opinion not incredibly biased? youve owned an rm80, but have you owned a real, full sized 2 stroke? have you actually spent alot of time on one? how can you get away with calling 2 strokes wasteul? lets take a 10 hour ride, what do you do? change your oil, what does your bike hold? a quart?? whether you pour it on the ground, or give it to someone who is going to put it in their furnace, its worse for the environment than the 1/4 of a quart of cleaner burning premix i used. and does your four stroke not hold more tranny fluid than my 2 stroke? does the incredibly high decibel output thanks to exhaust manufacturers of four strokes not equally help our riding areas get shut down? does an expansion chamber not force the unburned mixture back in? and for the small amount of time that a 2 stroke is not in the powerband does a powervalve not help significantly with this?
the answers are all yes.

[tigmaster]

Eh... You may want to ave a read up on some of your facts.

First off, I have spent a significant amount of time on a YZ250 (big bore 300cc) seeing as that is what is sitting in my girlfriends garage. Not too impressed. Also, I beat it in a race with Jim riding it so rider experience wasn't the issue.

No lets compare oil if you would like. Lets say it is actual 10 engine hours to be most specific. My bike drains 0.69L (0.73Qts) at a filter and oil change. You run what 40:1??? That is 3.2 ounces per gallon. Lets say you use 7 gallons of gas in 10 engine hours. This figure is completely reasonable if you are counting engine hours. That is 22.4 ounces or 0.70Qts... Daringly close to my consumption of oil. Now lets just say since I have a separated transmission compartment that we can get away with changing our tranny oil at the same time. Reasonable? I would say so in our hypothetical assumption. My transmission holds 0.59L (0.62Qts). How much does your transmission see??

Exhaust, well ya got me there. No arguing that. That what quiet pipes are for. Obviously people screw us over in that category.

The powervalve is designed to give two strokes some bottom end torque by increasing the CR at lower RPMs. No thought was put into environmental concerns.

Expansion chamber, once again... This guy is used to create a partial vacuum to increase evacuation of exhaust gasses. Not really designed to be putting anything back into the chamber. If something does get in, not enough to make a difference. The whole design of this guy is to get stuff out as fast as possible.

Now lets talk about fuel consumption. Another area where two strokes lose. Guarantee you use more fuel than me per engine hour. Why is that? Simple fact of inefficiencies in your engine. Just to name a few are lack of valves ( no way to precisely control fuel mixture) and the large bulbous excuse of extracting some power from the engine (expansion chamber). Hey that's more oil for you there too.

[BansheeRider]

well, unless we were hitting it at the track hard, 7 gallons is unreasonable.
in chadwick, 7 gallons is all day. still, you admited, your bike still uses more oil and more oil is wasted. not to mention the slipper piston blowby which shortens the life of your oil significantly, personally, i would change it before 10 hours.
my transmission holds 700cc's, so yours only holds 590cc's, thats not an incredible difference.
the expansion chamber pushes "into" the cylinder, any gas that leaves prematurely will be pushed back in.
agree?
still, while most people do not get that its not half, the 2 stroke can still make the same power with much less displacement.
agree?




1 more thing, there has to be something wrong with that bike, you know that a crf450 shouldnt come near a yz300.
your girlfriend being a new rider, maybe she lugged it too much, and the reeds are bad, or most likely, maybe the top end is old, and it has low compression

[gscx]

ok, so my brother has a 2001 300mxc that has been ported and polished, head mod, shaved rotor to almost nothing and a FMF fatty pipe. That bike is pretty ****ing gay to ride. Absolutey NO fun to ride. I know Tigs GF is faving no fun riding that bike, i dont see how she could really

[Hardtail]

I have a question, please remember that I have not had alot of time on dirt bikes. Why is it that they compare 125cc's to 250cc's and 250cc's to 450cc's. It doesn't seem fair because of the larger cc's. I know you have to keep the 2-stroke in the power band and the 4-stroke has more torque, but the cc advantage doesn't seem fair. Any thoughts would help alot. Thanks

[BansheeRider]

if you mean about the 250 having a 50cc advantage, its because a 200cc would get blown away. a 250 still doesnt make what a 450 does

[Hardtail]

Originally Posted by tjscott2012

if you mean about the 250 having a 50cc advantage, its because a 200cc would get blown away. a 250 still doesnt make what a 450 does

The AMA had a 125 and a 250 2-stroke compitition
How can you compare that to a 250, 450 4- stroke compitition

250cc - 125cc = 75cc

450cc - 250cc = 200cc

I just don't see how you can compare them, they are two differant animals. Both good in their own ways.

I think they should have seperate races.

[BansheeRider]

ya, but a two stroke makes equal, (or close) power at half the displacement of the four stroke, so its more fair to give them more displacement
i think the 2 stroke should be allowed to be 144's, it would be much more even

[BansheeRider]

Originally Posted by gscx

ok, so my brother has a 2001 300mxc that has been ported and polished, head mod, shaved rotor to almost nothing and a FMF fatty pipe. That bike is pretty ****ing gay to ride. Absolutey NO fun to ride. I know Tigs GF is faving no fun riding that bike, i dont see how she could really

why is it gay to ride?
thats a well respected bike, what didnt you like about it?