2 stk & 4 stk handling

Permeance_Flux
I want to explain to my friend the characteristics of a 2 stroke being more of a rear steering bike, whereas a 4 stroke has more weight over the front end.

This is due to power delivery not chassis geometry right?
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Dirty Points 7/29/2021 11:40am
7/29/2021 11:40am
Permeance_Flux wrote:
I want to explain to my friend the characteristics of a 2 stroke being more of a rear steering bike, whereas a 4 stroke has more...
I want to explain to my friend the characteristics of a 2 stroke being more of a rear steering bike, whereas a 4 stroke has more weight over the front end.

This is due to power delivery not chassis geometry right?
Both of those as well as engine braking characteristics, different center-of-gravity, rotating mass,and overall weight.
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Falcon
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Falcon 7/29/2021 11:46am
7/29/2021 11:46am
You are right and wrong. Here's how I see it:

The "weight over the front end" thing is geometry. Both bikes would have similar fore/aft weight balance due to the frame angles.

"Rear wheel steering" vs. "Front wheel steering" is really a misnomer. It comes more from the ability to powerslide or steer while the wheel is spinning. Two strokes tend to be more "rear wheel" -ish, because not only do they break free more easily, but they also aren't as likely to gyro-stabilize when the engine is turning over. Thus, you can turn a 2-stroke with the power on and the rear wheel spinning (rear-wheel steer,) while on a 4-stroke you would tend to corner first, and then lay on the power as you are exiting the turn (front-wheel steering.) This is why my buddy is so amazed I can get on the throttle so early in the turns. It's not really me being that good; it's just that the smoker makes it easy.

Handling is by far the #1 reason why I hate four strokes. When cornering a 4-stroke, if you grab a handful of throttle like I do on my 250, you are likely to stand straight up and go straight off the track. Grinning
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skeef
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skeef 7/29/2021 12:06pm
7/29/2021 12:06pm
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride more on the back wheel & let the front dance.

I think answers will vary person to person, with some consistancy between them all. The answer is go ride them both and see for yourself.
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GrapeApe
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GrapeApe 7/29/2021 2:18pm
7/29/2021 2:18pm
Chassis geometry and weight balance determine handling, not the configuration of the motor.
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Falcon
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Falcon 7/29/2021 3:11pm
7/29/2021 3:11pm
^ I disagree entirely. Although chassis geometry is a larger component of handling, the engine characteristics make a huge impact. I'd even go so far as saying 60/40. This is why manufacturers who make both do not simply put the different engines into the same frames.
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CivBars
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CivBars 7/29/2021 3:17pm
7/29/2021 3:17pm
GrapeApe wrote:
Chassis geometry and weight balance determine handling, not the configuration of the motor.
Explain
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skypig
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skypig 7/29/2021 3:36pm
7/29/2021 3:36pm Edited Date/Time 7/29/2021 3:36pm
Falcon wrote:
^ I disagree entirely. Although chassis geometry is a larger component of handling, the engine characteristics make a huge impact. I'd even go so far as...
^ I disagree entirely. Although chassis geometry is a larger component of handling, the engine characteristics make a huge impact. I'd even go so far as saying 60/40. This is why manufacturers who make both do not simply put the different engines into the same frames.
Agreed.

The Ractech Suspension Bible claims:
“A change in flywheel weight can feel like a change of compression damping”.

So totally changing the engine weight, rotating mass, and power delivery could have a huge impact on “handling”.
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wrc777
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wrc777 7/29/2021 5:23pm
7/29/2021 5:23pm
The extra engine braking of a four stroke puts a lot more weight on the front tire. That alone affects the handling quite a bit.

Ktm four and two stroke chassis look the same but are they? I know the fork valving is a lot different.
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Undersprung
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Undersprung 7/29/2021 6:50pm
7/29/2021 6:50pm
skeef wrote:
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride...
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride more on the back wheel & let the front dance.

I think answers will vary person to person, with some consistancy between them all. The answer is go ride them both and see for yourself.
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The engine braking really helps the front feel planted and gives me so much more confidence.
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wrc777
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wrc777 7/29/2021 8:11pm
7/29/2021 8:11pm
skeef wrote:
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride...
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride more on the back wheel & let the front dance.

I think answers will vary person to person, with some consistancy between them all. The answer is go ride them both and see for yourself.
Undersprung wrote:
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The...
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The engine braking really helps the front feel planted and gives me so much more confidence.
Yeah it acts as a drag brake and makes the front stick better. A two stroke has less inertia so you can throw it around more, but the front end almost always has less pressure on it on or off power. Where the two stroke has an advantage is in twisty sections and s curves where the lighter inertia allows you to transition side to side more quickly. You should be able to lay into a rut more quickly on the two stroke, but I think they don’t generate nearly the front end grip in flat corners.
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Falcon 7/30/2021 8:27am
7/30/2021 8:27am
skeef wrote:
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride...
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride more on the back wheel & let the front dance.

I think answers will vary person to person, with some consistancy between them all. The answer is go ride them both and see for yourself.
Undersprung wrote:
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The...
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The engine braking really helps the front feel planted and gives me so much more confidence.
wrc777 wrote:
Yeah it acts as a drag brake and makes the front stick better. A two stroke has less inertia so you can throw it around more...
Yeah it acts as a drag brake and makes the front stick better. A two stroke has less inertia so you can throw it around more, but the front end almost always has less pressure on it on or off power. Where the two stroke has an advantage is in twisty sections and s curves where the lighter inertia allows you to transition side to side more quickly. You should be able to lay into a rut more quickly on the two stroke, but I think they don’t generate nearly the front end grip in flat corners.
I always felt like the engine braking of a 4-stroke makes me endo. Then, when I get on the gas, it wants to go straight instead of turning. I seriously look like a goon trying to ride one of those contraptions.
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Owen H
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Owen H 7/30/2021 8:39am
7/30/2021 8:39am
Handling can be sloppily defined as the relationship between tire and surface. So to say that engine configuration doesn't play a role in this is akin to saying that having a broken hand doesn't affect your handwriting because you're still using a pen.

Power delivery characteristics are the key factor here. You can verify this by the near 100% rate of people saying adding a flywheel weight literally made their bike feel brand new. I am part of that group.
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Owen H
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Owen H 7/30/2021 8:42am
7/30/2021 8:42am
Undersprung wrote:
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The...
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The engine braking really helps the front feel planted and gives me so much more confidence.
Similar position and I agree 100%. Four strokes just corner better IMO.
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GrapeApe 7/30/2021 8:54am
7/30/2021 8:54am
GrapeApe wrote:
Chassis geometry and weight balance determine handling, not the configuration of the motor.
CivBars wrote:
Explain
There are two strokes that handle razor sharp and two strokes that handle like boats (RM vs. KX). There are four strokes that handle razor sharp and four strokes that handle like boats (CRF vs. YZF). Everything on a motorcycle contributes to handling, so in that regard I agree motor characteristics affect handling. But that main thing that determines if a bike handles quick and twitchy or planted and stable is chassis geometry and weight balance.
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usp4u
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usp4u 7/30/2021 9:05am
7/30/2021 9:05am
I've always viewed the "rear steering" thing like this:

Once a 2T starts spinning the rear tire, it is more apt to keep spinning due to the engine generating a power pulse on every revolution. The 4T has a power pulse every other revolution and is more apt to maintain or regain traction. This is why the rear of a 4T is less busy and the bike is aimed more with the front tire.
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Falcon 7/30/2021 11:41am
7/30/2021 11:41am
usp4u wrote:
I've always viewed the "rear steering" thing like this: Once a 2T starts spinning the rear tire, it is more apt to keep spinning due to...
I've always viewed the "rear steering" thing like this:

Once a 2T starts spinning the rear tire, it is more apt to keep spinning due to the engine generating a power pulse on every revolution. The 4T has a power pulse every other revolution and is more apt to maintain or regain traction. This is why the rear of a 4T is less busy and the bike is aimed more with the front tire.
That's very astute, and I agree. 2-strokes are definitely more squirrely.
CivBars
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CivBars 7/30/2021 12:35pm
7/30/2021 12:35pm
GrapeApe wrote:
Chassis geometry and weight balance determine handling, not the configuration of the motor.
CivBars wrote:
Explain
GrapeApe wrote:
There are two strokes that handle razor sharp and two strokes that handle like boats (RM vs. KX). There are four strokes that handle razor sharp...
There are two strokes that handle razor sharp and two strokes that handle like boats (RM vs. KX). There are four strokes that handle razor sharp and four strokes that handle like boats (CRF vs. YZF). Everything on a motorcycle contributes to handling, so in that regard I agree motor characteristics affect handling. But that main thing that determines if a bike handles quick and twitchy or planted and stable is chassis geometry and weight balance.
lol You silly purple monkey. Such a jokester!
skeef
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skeef 7/30/2021 12:44pm
7/30/2021 12:44pm
skeef wrote:
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride...
2t corner better, lighter on the wheels, flickable, ride over the top of the bike. vs. 4t stable, power everywhere, easier to ride, engine breaking, ride more on the back wheel & let the front dance.

I think answers will vary person to person, with some consistancy between them all. The answer is go ride them both and see for yourself.
Undersprung wrote:
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The...
Interesting. I feel like I corner a lot better on the 4 stroke I recently got after riding a 2 stroke for a few years. The engine braking really helps the front feel planted and gives me so much more confidence.
Yeah I mean this is completely opinion based. I think the engine braking makes it easier to get in the corner, but while in the corner I can dig a 2t out and hang it down way lower than my 450. I ride a 450 95% of the time too..

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250 cross
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250 cross 7/30/2021 3:29pm
7/30/2021 3:29pm
I only ride on my home turn track but on both a smoker and two two fiddy f's. For me, I tend to ride cut and thrust on the two stroke and on the four strokes I ride more sweeping lines. Always figured the reason for the difference was just the length of the powerbands.
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PTshox 7/31/2021 12:25am
7/31/2021 12:25am
Don't forget the impact on the suspension a 2 stroke vs 4 stroke engine has; a 2 stroke has more intake charge explosions in a given amount of time and it has an effect on suspension performance.

To me, the 2 strokes are harder to setup the suspension on (rear mainly) do to the type of power and the amount of power cycles per given second.

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