250 vs 450 style/technique

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8/19/2019 2:27 PM

Current trend

250 guys, bounce every bike off the rev limiter


450 guys like Ken Roczen(best style) and many other greats in our sport keep the bike low in the RPMs...


Why is it that, none of the current 250 guys can keep the bike off the rev limiter?? or why do the greats keep the bike below 9,000rpm??


Is the difference simply because the 450 has too much power and the 250 doesnt have enough??

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8/19/2019 2:33 PM

TSCHAM101 wrote:

Current trend

250 guys, bounce every bike off the rev limiter


450 guys like Ken Roczen(best style) and many other greats in our sport keep the bike low in the RPMs...


Why is it that, none of the current 250 guys can keep the bike off the rev limiter?? or why do the greats keep the bike below 9,000rpm??


Is the difference simply because the 450 has too much power and the 250 doesnt have enough??

yes

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8/19/2019 2:46 PM

Isnt it obvious? 250s need the revs to go forward. The 450s make more tq at 6k than a 250 makes at 16k...

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8/19/2019 2:51 PM

TSCHAM101 wrote:

Current trend

250 guys, bounce every bike off the rev limiter


450 guys like Ken Roczen(best style) and many other greats in our sport keep the bike low in the RPMs...


Why is it that, none of the current 250 guys can keep the bike off the rev limiter?? or why do the greats keep the bike below 9,000rpm??


Is the difference simply because the 450 has too much power and the 250 doesnt have enough??

Yes, answered your own question. They dont need to bounce them off the limiter unless they're revving out in top though in my opinion...but they're getting a new engine every race meeting so they dont care.

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8/19/2019 2:58 PM

Ride a 250F and then go ride a 450. You’ll quickly see why you need to rev the 250

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2011 Yamaha YZ 250 -MX
1996 Yamaha Banshee 350 -Trails
1982 Chevy S10
2005 Pontiac GTO -451rwhp

8/19/2019 2:59 PM

TSCHAM101 wrote:

Current trend

250 guys, bounce every bike off the rev limiter


450 guys like Ken Roczen(best style) and many other greats in our sport keep the bike low in the RPMs...


Why is it that, none of the current 250 guys can keep the bike off the rev limiter?? or why do the greats keep the bike below 9,000rpm??


Is the difference simply because the 450 has too much power and the 250 doesnt have enough??

AE448 wrote:

Yes, answered your own question. They dont need to bounce them off the limiter unless they're revving out in top though in my opinion...but they're getting a new engine every race meeting so they dont care.

okay.. Original Post was not a good explanation/question.


Simply, why doesnt any 250 rider short shift their bikes? Dont pretty much all of the bikes make more torque below 9000rpm? Plus, the short shifting would make it an easier transition to a 450??

Am i losing my mind? I might be, my wife is 41 weeks pregnant and i have a 2 year old..

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8/19/2019 3:01 PM

TSCHAM101 wrote:

Current trend

250 guys, bounce every bike off the rev limiter


450 guys like Ken Roczen(best style) and many other greats in our sport keep the bike low in the RPMs...


Why is it that, none of the current 250 guys can keep the bike off the rev limiter?? or why do the greats keep the bike below 9,000rpm??


Is the difference simply because the 450 has too much power and the 250 doesnt have enough??

AE448 wrote:

Yes, answered your own question. They dont need to bounce them off the limiter unless they're revving out in top though in my opinion...but they're getting a new engine every race meeting so they dont care.

TSCHAM101 wrote:

okay.. Original Post was not a good explanation/question.


Simply, why doesnt any 250 rider short shift their bikes? Dont pretty much all of the bikes make more torque below 9000rpm? Plus, the short shifting would make it an easier transition to a 450??

Am i losing my mind? I might be, my wife is 41 weeks pregnant and i have a 2 year old..

The 250s wont pull it. The 250fs need the revs.

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8/19/2019 3:10 PM

eric513anderson wrote:

Ride a 250F and then go ride a 450. You’ll quickly see why you need to rev the 250

i currently ride a 250f... but with all the new bikes being developed up top... wouldnt a stronger/torque curve allow the bike to be ridden lower in the RPM's... The Star Yamaha bikes dont seem to be bouncing off rev limiters, they are more 450 like.. and they have the bike to be on in my opinion..

the Hondas are known to be top end machines, but all the factory geico riders are saying their bikes are too slow(via pulpmx and all Steve's nonsense).. Are the OEM's going the wrong direction? seems like we are going more towards a 250 2 stroke type of power...

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8/19/2019 4:23 PM

eric513anderson wrote:

Ride a 250F and then go ride a 450. You’ll quickly see why you need to rev the 250

TSCHAM101 wrote:

i currently ride a 250f... but with all the new bikes being developed up top... wouldnt a stronger/torque curve allow the bike to be ridden lower in the RPM's... The Star Yamaha bikes dont seem to be bouncing off rev limiters, they are more 450 like.. and they have the bike to be on in my opinion..

the Hondas are known to be top end machines, but all the factory geico riders are saying their bikes are too slow(via pulpmx and all Steve's nonsense).. Are the OEM's going the wrong direction? seems like we are going more towards a 250 2 stroke type of power...

The 250 has to rev higher to make the torque. Its physics. Youll never get enough downward force on a 250 piston to match the downward force on a 450 piston.

10PSI on a 3” piston produces less power than 10PSI on a 6” piston.

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8/19/2019 4:45 PM

eric513anderson wrote:

Ride a 250F and then go ride a 450. You’ll quickly see why you need to rev the 250

TSCHAM101 wrote:

i currently ride a 250f... but with all the new bikes being developed up top... wouldnt a stronger/torque curve allow the bike to be ridden lower in the RPM's... The Star Yamaha bikes dont seem to be bouncing off rev limiters, they are more 450 like.. and they have the bike to be on in my opinion..

the Hondas are known to be top end machines, but all the factory geico riders are saying their bikes are too slow(via pulpmx and all Steve's nonsense).. Are the OEM's going the wrong direction? seems like we are going more towards a 250 2 stroke type of power...

kb228 wrote:

The 250 has to rev higher to make the torque. Its physics. Youll never get enough downward force on a 250 piston to match the downward force on a 450 piston.

10PSI on a 3” piston produces less power than 10PSI on a 6” piston.

im not a physicist or an engineer.. but then how do the yz250f motors produce so much more torque? this is purely just because im interested.. i dont know much about this topic and wanna learn.

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8/19/2019 5:15 PM

TSCHAM101 wrote:

i currently ride a 250f... but with all the new bikes being developed up top... wouldnt a stronger/torque curve allow the bike to be ridden lower in the RPM's... The Star Yamaha bikes dont seem to be bouncing off rev limiters, they are more 450 like.. and they have the bike to be on in my opinion..

the Hondas are known to be top end machines, but all the factory geico riders are saying their bikes are too slow(via pulpmx and all Steve's nonsense).. Are the OEM's going the wrong direction? seems like we are going more towards a 250 2 stroke type of power...

kb228 wrote:

The 250 has to rev higher to make the torque. Its physics. Youll never get enough downward force on a 250 piston to match the downward force on a 450 piston.

10PSI on a 3” piston produces less power than 10PSI on a 6” piston.

TSCHAM101 wrote:

im not a physicist or an engineer.. but then how do the yz250f motors produce so much more torque? this is purely just because im interested.. i dont know much about this topic and wanna learn.

Could have something to do with the reverse cylinder and downdraft intake that all the other oems are trying to replicate with a traditional motor layout.

You also gotta remember the 450 has a lot more inertia from the rotating mass, if you rotate it faster it makes the bike behave differently. So not only are 450s designed to work well in the lower rpms, even if they were set up to do the opposite, the bikes would become a lot more dangerous.

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8/19/2019 5:17 PM

listen to a pro on a 125 vs a 250 2t.

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8/19/2019 7:39 PM

TSCHAM101 wrote:

i currently ride a 250f... but with all the new bikes being developed up top... wouldnt a stronger/torque curve allow the bike to be ridden lower in the RPM's... The Star Yamaha bikes dont seem to be bouncing off rev limiters, they are more 450 like.. and they have the bike to be on in my opinion..

the Hondas are known to be top end machines, but all the factory geico riders are saying their bikes are too slow(via pulpmx and all Steve's nonsense).. Are the OEM's going the wrong direction? seems like we are going more towards a 250 2 stroke type of power...

kb228 wrote:

The 250 has to rev higher to make the torque. Its physics. Youll never get enough downward force on a 250 piston to match the downward force on a 450 piston.

10PSI on a 3” piston produces less power than 10PSI on a 6” piston.

TSCHAM101 wrote:

im not a physicist or an engineer.. but then how do the yz250f motors produce so much more torque? this is purely just because im interested.. i dont know much about this topic and wanna learn.

The smoother the track is for airflow the more power you make(basically). If your intake has a lot of turbulence it hurts power. Thats why boyesen created the RAD valve on 2 strokes. Its smoother. Its also why 2 strokes get the transfer ports smoothed out and why the heads on 4 strokes get ported. A smooth transition from intake to exhaust is best.

Yamaha has that backwards engine design. It essentially has a ram air intake like a supersport. Its a more natural flow of gasses. Bike is going forward, air goes in the front and exhaust out the back. Whereas the traditional design is air in the back and exhaust out the back..

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8/19/2019 9:58 PM

TSCHAM101 wrote:

i currently ride a 250f... but with all the new bikes being developed up top... wouldnt a stronger/torque curve allow the bike to be ridden lower in the RPM's... The Star Yamaha bikes dont seem to be bouncing off rev limiters, they are more 450 like.. and they have the bike to be on in my opinion..

the Hondas are known to be top end machines, but all the factory geico riders are saying their bikes are too slow(via pulpmx and all Steve's nonsense).. Are the OEM's going the wrong direction? seems like we are going more towards a 250 2 stroke type of power...

kb228 wrote:

The 250 has to rev higher to make the torque. Its physics. Youll never get enough downward force on a 250 piston to match the downward force on a 450 piston.

10PSI on a 3” piston produces less power than 10PSI on a 6” piston.

TSCHAM101 wrote:

im not a physicist or an engineer.. but then how do the yz250f motors produce so much more torque? this is purely just because im interested.. i dont know much about this topic and wanna learn.

More torque than what? A KTM? I don’t know that they do. You want more power from a KTM just turn the throttle more. It’s mapping and throttle response (KTM is smooth and linear rather than jumpy when you turn the throttle a bit) more so than actual torque. I’ve not seen any dyno showing the YZ with extraordinary torque numbers.

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Current rides: 2016 KTM 250SXF, 2017 KTM 350SXF