hard packed dirt and a 2 stroke

[Tony477g]

how many of you ride hard packed stuff on a 2 stroke? my number one question is how! Maybe its just my memory but i remember trying get the back tire to grip was extremely hard(i was riding a yz125). Switched to a 4 stroke and trail/mx riding has been easier for the really hard packed stuff. Thinking about making the switch back though(150sx). because the extra weight and rotational mass of the 250f has made me low side plenty of times, and on the 2 stroke if i ever started to go down i could almost always correct myself, I just cant justify going back to the 2t though when most everything out in the desert and at my track is hard packed. maybe it was the tire whats your experience with it

[Spyderwolf]

I run a maxxis sx on my 2t and hook up no problem in the hard pack tires make a difference no matter what your riding

[jwoodruff07]

I ride a yz125 at Durhamtown in Georgia all the time and it's like pavement on a few of the tracks. I'm running a Michelin MH3 and it hooks up well and lasts long too. I decided to go with a 110/90 instead of the 100/90 (the 110 is wider). I can't decide if I like the 110 more or not but I definitely get good traction!

[temporarily_locked]

clutch and throttle control. Fresh rear tires. Carry speed so you don't have to accelerate on jump faces, you can just kind of blip the throttle.

[SOAB_465]

I used to have the same problems on my 250.

Out of curiosity did you have an aftermarket clutch lever on your YZ? The reason I ask, is that most unbreakable style levers use the Honda ratio. On YZs the Honda lever makes the clutch actuation more like a light switch. I have a Zeta unbreakable lever in the stock perch now, which has buttery smooth engagement. The stock levers are good too, but they bend pretty easy.

When I switched to the Zeta it felt like traction control, for real.

[lowmass]

2 strokes have a very different power "profile" than the 4 regardless of engine size. We could get into the details of why but to keep it simple lets just say the 2 stroke has a smaller "window" where it makes its power. If you look at a graph of 2 vs 4 power the 4 tends to have a graph that looks like a "mound" were the 2 has a graph that looks more like a "peak". This is where the word "peaky" comes from and is why the 2 is harder to get a grip with. It wants to accelerate too fast and ends up breaking loose on hard slick surface.

This is the basic characture of these two motor types. HOWEVER this doesnt mean with a bit of skill and practice you cannot use the 2s power effectivly on the slick hard pack. What you will have to do is learn to use the clutch. The problem is what does that mean exactly. Well it doesnt mean "fanning" the clutch. Gross clutching is almost usless.

What helped me learn to use the clutch effectivly is to think of it as a second throttle. I think of the clutch as the power delivery lever. I dont slap it or fan it. Instaed I pull it in or let it out smoothly so that it smooths out the power delivery. I think of the cluthch more as a way to get a smooth tractable flow of power.

U can practice this in a straight line. Pull clutch in, let out slowly as u r acclerating. Get a feel 4 it. Go ahead and exagerate things just to get the feel. In corners you can actually have the motor tapped out making max power BUT use the clutch to deliver it by smoothly letting it out. Eventually you can get a good feel for it and u start to just pull the clutch a bit into a turn and slowly let it out as you twist the throttle. The clutch is by far the best power smoothing device u have. Way better than any mod to the motor including heavy flywheels.

[tye1138]

Most of the tracks here in California are hard pack and I ride both 2 strokes and 4 strokes.

You can't beat a 4 stroke in terms of grip potential. Every time I get on a 4 stroke, having usually just spent the day riding my 2 stroke, it amazes me how much more grip they have. The reason is quite simple, a 2 stroke is sending power to the rear wheel almost all the time, it doesn't give the tire any time to rest. 4 strokes send power to the rear wheel 1/2 the amount of time as a 2 stroke, which means, in between each power pulse, there is a period of time where the tire can rest and settle in. This is why even BIG bore 2 strokes, don't have much more grip then 4 strokes, it has nothing to do with the bore, or even where the torque is on the power curve, it has everything to do with how the motor delivers that power to the rear wheel. At the same time though, when hard pack riding, the differences between the 2 stroke and 4 stroke are pretty minimal because the surface can be SO slippery that the benefits of the 4 stroke grip potential get nullified.

When dealing with corners in a hard pack situation, you have to realize that, without a berm or rut to lean against, there is very little traction. So you have to adjust the way you deal with corners to compensate for that. Throttle control, braking and lean angle are all changed in a hard pack situation. You need to be much more agile on the throttle to try and keep the rear wheel from spinning up too much. You need to brake upright because the front wheel won't wanna stick either. Lean angle is substantially reduced because the tires won't grip on hard pack very well and usually ruts are all blown out, so they become useless.

Railing the outside berm is always the preference when dealing with hard pack situations. Another method is to come in and square off the corner just like supercross. The key is to maintain as much speed as you can, without leaning the bike over too much, which will just kick the rear out.

Tires can play a considerable role when it comes to hard pack riding, especially when it comes to wear. Pretty much any intermediate tire works fine in hard pack situations. But all the manufacturers make hard pack tires, which have a slightly shorter knob and more of them, which is substantially stiffer then the intermediate. This "hard" tire allows for less wear over time and the stiffer carcass helps the tire keep its form instead of deflecting under the stresses of the hard surface.

Over-all, if you plan on riding a lot of hard pack, setting your bike up and adjusting your riding style to compensate will help you get around the track quicker.

[Tony477g]

would you give up your 2 stroke for a 4 stroke? hows your 144? I ride mostly trails but there are a couple of tracks out in the mountains people have built but are pretty tight and hard packed.

[tye1138]

would you give up your 2 stroke for a 4 stroke?

Like most people, I'm quicker on a 250F then I am on a 125, thats because the 250's don't require as much energy to get around the track, plus they grip all the time. All the energy you waste on a 125 shifting, clutching, dealing with sliding the bike around, all of that goes away with a 250F. All the 250F's I've ridden have so much more rotating mass, they act like a gyroscope and are much more stable. The rider can make tuns of mistakes and it doesn't effect the lap as much. My lil 125 is twitchy, super light weight, extremely powerful and if you don't connect the dots perfectly, you might as well get off the track and try it again the next lap around.

The benefits of riding a 2 stroke are huge. When I crash, my bike starts in 1 kick, every time. It costs much less to own and to be honest, 125's are a great learning tool and I ride to learn how to become better. Someday when I'm a good rider and have lots of excess money, I'll buy a nice 2012 KTM 250SX-F with the electric start, then I don't have to kick the thing when I crash! heh

hows your 144?

Still haven't ridden it yet! Long story... not for this thread!

Still on me 125 and very soon I'll be throwing the 144 motor into that frame and testing it! Full report coming soon! ?

[Tony477g]

Like most people, I'm quicker on a 250F then I am on a 125, thats because the 250's don't require as much energy to get around the track, plus they grip all the time. All the energy you waste on a 125 shifting, clutching, dealing with sliding the bike around, all of that goes away with a 250F. All the 250F's I've ridden have so much more rotating mass, they act like a gyroscope and are much more stable. The rider can make tuns of mistakes and it doesn't effect the lap as much. My lil 125 is twitchy, super light weight, extremely powerful and if you don't connect the dots perfectly, you might as well get off the track and try it again the next lap around.

The benefits of riding a 2 stroke are huge. When I crash, my bike starts in 1 kick, every time. It costs much less to own and to be honest, 125's are a great learning tool and I ride to learn how to become better. Someday when I'm a good rider and have lots of excess money, I'll buy a nice 2012 KTM 250SX-F with the electric start, then I don't have to kick the thing when I crash! heh

Still haven't ridden it yet! Long story... not for this thread!

Still on me 125 and very soon I'll be throwing the 144 motor into that frame and testing it! Full report coming soon! ?

I dont know what it is with these 4 strokes though but ive broken more bones on them. May just be a coincidence, I also believe though they have been harder for me to control in the air and in turns. I low side alot from the weight in some hard packed turns, heck even when i have a rut i low side. when i had a 2 stroke i remember being able to put a foot down and picking myself up before i hit the ground. In the air though is when i feel its heavy. Maybe its just me. Im getting a new bike and from what ive been reading theyre not that reliable(4 strokes) anymore. I really cant justify to buy a bike and at 30 hours need a new tranny and topend, or crank. I think i may just go back to the good ol 2 smoke

[tye1138]

I dont know what it is with these 4 strokes though but ive broken more bones on them. May just be a coincidence

Yea, thats probably a coincidence, you're probably are a better rider now on the 250F then you were on the 125 which means, you're taking more chances and the consequences are greater.

I also believe though they have been harder for me to control in the air and in turns. I low side alot from the weight in some hard packed turns, heck even when i have a rut i low side. when i had a 2 stroke i remember being able to put a foot down and picking myself up before i hit the ground. In the air though is when i feel its heavy.

Well, 125's are lighter bikes, so yea they feel lighter when you jump them. At the same time though, because they have so much more gyroscopic effect, they tend to fly better.

The bike's weight is not causing you to low side, you could have junky tires, poor suspension setup or need to work on your body position. If your having to plant your foot on the ground all the time, that tells me you probably aren't carrying enough speed or getting on the throttle early enough. If you're tapping the ground and still crashing, that tells me something is wrong in the way you're riding. If anything, your rear end should swing around on you because of the slick hard pack situation, which can be compensated with body position on the machine. Not being able to catch the machine, that has nothing to do with it being a 4 stroke, unless you have an unusually heavy bike.

Im getting a new bike and from what ive been reading they're not that reliable(4 strokes) anymore. I really cant justify to buy a bike and at 30 hours need a new tranny and topend, or crank. I think i may just go back to the good ol 2 smoke

Actually 4 strokes have never been that reliable. Guys who know how to ride, they'll burn through a new 250f in 20 - 30 hours no problem and that has never changed. Yamaha has spent a great deal of time developing a 250f motor that runs out of steam way before the redline, meaning the average rider doesn't have to abuse it to the point of failure. This is why you see a lot of yzf's out there with some high hours on them, without having done any service. Mind you, the YZF isn't the quickest bike, but it handles very well and its pretty damn reliable. On the other end of the spectrum is the KXF, which is a real race bike, high-revving, super fast (more power then any other bike in its class today) and is well suspended. If I were a 18 year old trying to race motocross, my garage would have 2 2012 KX250F's in it, one practice bike, one Pro Circuit works machine. I'd also have a spare motor because it WILL go pop when you don't want it to. The Suzuki and Honda are a mixed bag in my view, both bikes have their motor problems and the KTM as well has some issues, though I think the KTM 250SX-F will have to change for 2013, the 2012 model was rushed to production it looks like, so its actually nowhere near as good as the older ones.

Anyway, I still love 2 strokes and from that perspective you can buy a 2012 250SX and that bike hauls ass, its the best 250 ever made. If you really want an awesome bike, that's the way I'd head.

[Tony477g]

i dont low side to much but ya it may just be me. its not my suspension though, revalve plus have all the clickers and sag set. tires could be i dont like the mx51 in the front. I dont know, everywhere specially in turns and air the bike just has always felt heavy. Your probably taller and heavier than me at 5'5'' and 123 lbs im pretty small. Ive been hitting the gym though because ive been wanting a new bike and the 250f's weigh more than the one i own now, i used to weigh 110 lbs until i went to the gym. thats also the reason i dont consider the 250sx.

[sucmah]

i run 10# in both ends on my CR150, i couldnt get away with that on my KX250f, got flats. I attribute that to the fact my CR weighs 202lbs, anyway, the point is tire pressure can get you traction, dont be scared to run it down as long as you have good tubes.

[skich69]

im running maxxis desert IT's at about 12-15lbs. no problems in the hard or soft stuff. its just practice.

[tye1138]

i dont low side to much but ya it may just be me. its not my suspension though, revalve plus have all the clickers and sag set.

Ohh there is a lot more to suspension then trusting the suspension builder to give you the right settings. I spent days adjusting my suspension when I got it back from the builder recently, I'm still not happy with it. One of the problems with the PDS suspension, it's awesome if you dial it in perfectly, but if its not perfect, it has a tendency to not feel right.

tires could be i dont like the mx51 in the front.

Well yea, that is the worst MX front tire I've ever used. It lets go so quickly, you don't have any time to catch it in some cases. I had three pretty fun crashes, all low sides, because of that tire. When I switched to Bridgestone, I never had another problem. Mind you, the Dunlop's are still stellar tires and the MX31/MX71 front works fine, its just that 51. I'm actually gonna be switching back to Dunlop soon, going with a 31 front and 51 rear. As much as I like the bridgestones, I burn through them so quickly, they seem to only work for about 5 - 10 hours and then they're toast, even though they LOOK ok, the knobs bend too much under load and thats it. They are too soft of a carcass for the tracks out here.

Crash video: http://tye1138.com/stuff/newjumpmilestone.m4v

I dont know, everywhere specially in turns and air the bike just has always felt heavy. Your probably taller and heavier than me at 5'5'' and 123 lbs im pretty small. Ive been hitting the gym though because ive been wanting a new bike and the 250f's weigh more than the one i own now, i used to weigh 110 lbs until i went to the gym. thats also the reason i dont consider the 250sx.

Yea, I'm 5'11" and 150 - 160lb so for sure very different. It might actually take you MORE energy to ride the 4 stroke, just because your so small and light. These last few months I've been broke, so I haven't been riding much at all. But when I was riding 2 - 4 times a week, I was exercising in between rides and I felt great, had good fitness. I was doing 15 lap moto's like it was no problem and that was on a friends old KX250F. I was doing 20+ lap motos on my bro's 250SX-F no problem, yet 15 lap moto's on my 125 was like pulling teeth. I'm sad to say, a 6 lap moto today would be difficult, it does have a lot to do with fitness and size/weight for sure.

So yea, because of your weight/size, maybe a 125 is the right way to go.

[tacoma2stroke]

Im curious about how much much the tire pressure affects traction depending on terrain and climate. Common sense tells me that a stiff tire will take a corner better but im still pretty new at track riding. I ride a '94 kx 250 and im going riding on Sunday at a track so any info on recommended tire pressure would be appreciated!!

[tye1138]

Im curious about how much much the tire pressure affects traction depending on terrain and climate. Common sense tells me that a stiff tire will take a corner better but im still pretty new at track riding. I ride a '94 kx 250 and im going riding on Sunday at a track so any info on recommended tire pressure would be appreciated!!

It depends on the track/tire composition and conditions.

Softer compound tires obviously respond to pressures differently then harder compound tires.

The best place to start is 14 psi. The average active pressure range for motocross is 10 - 17 psi. On trails, sometimes people run less because they're dealing with super hard compound trail tires with larger sidewalls and can get away with lower pressures. On the track, if you run much lower then 10 psi, you'll tear through tubes like no tomorrow, been there, done that.

In hardpack situations, you want more rubber on the ground, more knobs on the tire and a harder compound material which can withstand it. In loamy situations, you want an intermediate tire, which has taller knobs and less of them, more for "digging" . These intermediate tires actually work great in the sand (softer conditions) where its nice to have a firm tire and big tall knobs that can dig more then the top layer.

[BlackCR25098]

2 strokes have a very different power "profile" than the 4 regardless of engine size. We could get into the details of why but to keep it simple lets just say the 2 stroke has a smaller "window" where it makes its power. If you look at a graph of 2 vs 4 power the 4 tends to have a graph that looks like a "mound" were the 2 has a graph that looks more like a "peak". This is where the word "peaky" comes from and is why the 2 is harder to get a grip with. It wants to accelerate too fast and ends up breaking loose on hard slick surface.

This is the basic characture of these two motor types. HOWEVER this doesnt mean with a bit of skill and practice you cannot use the 2s power effectivly on the slick hard pack. What you will have to do is learn to use the clutch. The problem is what does that mean exactly. Well it doesnt mean "fanning" the clutch. Gross clutching is almost usless.

What helped me learn to use the clutch effectivly is to think of it as a second throttle. I think of the clutch as the power delivery lever. I dont slap it or fan it. Instaed I pull it in or let it out smoothly so that it smooths out the power delivery. I think of the cluthch more as a way to get a smooth tractable flow of power.

U can practice this in a straight line. Pull clutch in, let out slowly as u r acclerating. Get a feel 4 it. Go ahead and exagerate things just to get the feel. In corners you can actually have the motor tapped out making max power BUT use the clutch to deliver it by smoothly letting it out. Eventually you can get a good feel for it and u start to just pull the clutch a bit into a turn and slowly let it out as you twist the throttle. The clutch is by far the best power smoothing device u have. Way better than any mod to the motor including heavy flywheels.

I have just gotten back into this sport and re-learning all techniques. Through constantly overthinking all the physical technique I've completely forgotten about clutch power delivery (which I get) and used to be great @. This will help me out a lot on saturday @ field of dreams and I've been so worried about jumping and leaning etc. I forget about power delivery with the clutch. My corners have been terrible because I don't have the clutch in at all. Alot of times people say 2 contradicting things but this will be good for me. Just saying thanks and anyone else listen to this guy he knows his stuff.

[BlackCR25098]

Oh btw OP, you're tires have the most grip neither on the throttle nor on the brake...The BEST traction you can get is when you are doing neither of those 2, just cruising. This goes exactly the same in a car, say you run off the road most people freak out and slam the brakes right? Which automatically loses all traction as well as acceleration. The best thing you can do when you run off the road is hit neither gas or brake, as it's when you get best traction and slowly drift back onto the road.

If you find yourself in a situation losing traction, try to fan the brake like ABS system and that time in between hitting the brake is when you're getting best traction. Other than that, it's all in the clutch especially out of corners. Think of your best traction into the corner is what I mentioned above, and your best traction out of corners is your clutch control, that's It!!

2 stroke is all HP top end which is why it spins to much, where as 4 strokes have that low end TORQUE which allows the tire to pulse more between accelerations. Hope that helps in some way.

[tye1138]

If you find yourself in a situation losing traction, try to fan the brake like ABS system and that time in between hitting the brake is when you're getting best traction. Other than that, it's all in the clutch especially out of corners. Think of your best traction into the corner is what I mentioned above, and your best traction out of corners is your clutch control, that's It!!

There sadly is no time to modulate the brakes in motocross, unless you're going slow. Usually you don't know when you're gonna loose traction until its too late and your foot is on the ground picking up the bike. Plus, modulating the brakes always, is a poor technique, all it does is slow you down. In motocross, traction is generated ON the brakes because the front end compresses and that helps push the tire into the ground. So being on the brakes when going into a bermed or rutted corner is a skill widely used, its not trail braking like in roadracing, but its a very similar cousin.

Using the clutch out of corners actually spins up the wheel and delivers LESS traction. You use the clutch to match the motor's RPM with the forward velocity of the machine instead of using the gear shifter to change gears. Its a "cheat" to get around an improper gear selection OR to generate speed quicker without changing gears. On my lil 125, its used exiting every corner, mostly to keep the motor in the higher RPM band (since 125's power is up at the higher RPM) without having to change down a gear.

2 stroke is all HP top end which is why it spins to much, where as 4 strokes have that low end TORQUE which allows the tire to pulse more between accelerations.

Got that kinda mixed up, read what I said earlier, that will explain it in more detail.