150rguy

I got fat bars!
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Dec 21, 2006
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Yeah, I've been startin to miss the powerband of a 2t to.
 

IndyMX

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You do understand that a powerband isn't a part like a piston right?


Powerband:
The area of RPM range where a engine produces the most power.
 

150rguy

I got fat bars!
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Dec 21, 2006
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I think he means is there any thing that you can ajust to make your powerband different.
 

IndyMX

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150rguy said:
I think he means is there any thing that you can ajust to make your powerband different.

Yeah, I was aware of that...

There are a lot of things you can do to change the powerband on a bike...

The most effective methods require modifying the engine.

If that's not possible, then there are a few things you can do to move the power around on your bike.

Like a different pipe. Or change the final drive ratio with different sized sprockets.

Do a search on here, you are likely to find the answers you are looking for.
 

elcamino12sec

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Jan 16, 2006
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Just curious what do you not like about your bikes power delivery? After reading about the new crf150R in the mini thumper section of this forum they are saying how much of an advantage it has over the 85cc t2's. Most people make it sound like they are going to refinance the farm and buy the new 150R as soon as their dealer gets one in stock.
 

150rguy

I got fat bars!
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Dec 21, 2006
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Well for me I like mine. I had an 85 and I liked that to. This bike is nice just because it easier to ride, but it's very loud. If I ever just want to go out and have a nice leisurely ride i would prefer my bike, Now if I was going out to do some harder faster riding the 150r is good for that to, but 85s are also good and fun for that. So it's kinda a toss up at which I like more. I don't know why dirtbike_freak wants to change his, he hated my kx85.
 

FruDaddy

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IndyYZ85 said:
Like a different pipe. Or change the final drive ratio with different sized sprockets.

Do a search on here, you are likely to find the answers you are looking for.
Not to attack you Indy, but changing sprockets will not affect the powerband of the motor, but it will alter the percieved power delivery. Changing the final gearing is effectively the same thing as permanenly shifting gears. Your engine makes the same power in first as it does in fifth, the gearing difference provides for more torque multiplication and a quicker rev up under load in the lower gears. Changing the sprockets is, however, a great way to find tune your acceleration and top speed, as well as a decen t way to make a bike seem to have more bottom end power. Higher gear ratios will also seem to smooth out the powerband and soften the hit by stretching things out a bit, and reducing the torqe that reaches the ground.

Otherwise, you are correct, changing the pipe, installing a better filter, better reeds, porting, and anything else that increases the amount of air that is pumped through the engine will push the powerband higher into the RPM range. This type of mod will move the torque curve, and increase peak HP, while taking away bottom end torque. Basically, making it more like a 2-stroke. Engines that are built specifically for high RPM operation (drag race, etc) are put together with airflow in mind, of course, you can go too far and ruin the whole thing. If you want a 2-stroke powerband, get a 2-stroke, it will cost less than trying to mod the thumper.
 

Moose

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He said

"Or change the final drive ratio with different sized sprockets"

Offering another option instead of doing motor work.
 

XRpredator

AssClown SuperPowers
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FruDaddy said:
. . . changing the pipe, installing a better filter, better reeds, porting, and anything else that increases the amount of air that is pumped through the engine will push the powerband higher into the RPM range.
as long as we're picking nits . . . I'd like to see one of these reed valves for thumpers.

making a smaller endcap for the muffler will quiet the bike down and also change the power characteristics, depending on cam timing and whatnot, of course.
 

FruDaddy

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Aug 21, 2005
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Elliot, I got that, but the question was about the power band, and changing the sprockets will not actually change that, :fft: perhaps you should go back and read my post as closely as Pred.

Pred, you got me, my engine bogged a bit on that one. :bang: :yell: Touche!! But having reminded me, cam timing, shape, and lift all play a huge role in where the powerband is, and how broad. The smaller endcap would likely push the power lower in the rev range, which is opposite of what the op wants to know.
 

IndyMX

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FruDaddy said:
Not to attack you Indy, but changing sprockets will not affect the powerband of the motor, but it will alter the percieved power delivery. Changing the final gearing is effectively the same thing as permanenly shifting gears. Your engine makes the same power in first as it does in fifth, the gearing difference provides for more torque multiplication and a quicker rev up under load in the lower gears. Changing the sprockets is, however, a great way to find tune your acceleration and top speed, as well as a decen t way to make a bike seem to have more bottom end power. Higher gear ratios will also seem to smooth out the powerband and soften the hit by stretching things out a bit, and reducing the torqe that reaches the ground.

Otherwise, you are correct, changing the pipe, installing a better filter, better reeds, porting, and anything else that increases the amount of air that is pumped through the engine will push the powerband higher into the RPM range. This type of mod will move the torque curve, and increase peak HP, while taking away bottom end torque. Basically, making it more like a 2-stroke. Engines that are built specifically for high RPM operation (drag race, etc) are put together with airflow in mind, of course, you can go too far and ruin the whole thing. If you want a 2-stroke powerband, get a 2-stroke, it will cost less than trying to mod the thumper.

I know changing sprockets will not change the powerband, but, since the OP is a 14year old kid, I didn't think going into detail about such matters would be of much use.
 

FruDaddy

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Aug 21, 2005
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Hopefully, the details will keep the kid from believing (and spreading) untruths. Also, they just might inject a dose of reality that is likely needed in this day and time. There is no easy way out, and many of todays kids need to realize that, they will be running our country soon.
 

IndyMX

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FruDaddy said:
Hopefully, the details will keep the kid from believing (and spreading) untruths. Also, they just might inject a dose of reality that is likely needed in this day and time. There is no easy way out, and many of todays kids need to realize that, they will be running our country soon.


Stop trying to scare me. It's just not nice!
 
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