Who knows primary weights?
Sep 23, 2001 | 10:00 AM
#1
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I am curious about the shape of the weight and how it affects the way the primary engages and shifts. Does anyone out there know how that works? I know all about heavier and lighter weights and also stiffer and lighter springs. I am sure that the shape of the weight has an effect on the way it engages and shifts. If the bulk of the weight was at the end then I would think that it would engage a little lower but then shifter really fast. If the bulk of the weight was closer to the pivit point then I would think it would have a higher engagement and shift slower. Does this make any sence? Does anyone out there know?
Sep 23, 2001 | 05:50 PM
#2
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Yes, Elroy you are on the right track with your theory. The curve (shape)of the weight will also make a difference in the shifting properties of the primary clutch. Then there is also notching of the weight to consider for engagement points.
Looks like you have just found out that it is currently in Spam wordSpam word Spam wordSpam word Spam wordSpam word Spam wordSpam word Spam wordSpam word to ignore the vast majority of questions regarding cvt clutching.
I suspect a few reasons exist for this phenomenon.
#1. The average reader doesn't have a clue what you are asking.
#2. It took so long for some people to figure out the answer they don't want to give you the answer freely.
#3. Those that do know, don't want you to know. There is too much money to be made in the sale of clutch kits (and colored springs) and the sale of other misinformation.
#4. The old timers who know the answers have moved on or been driven off by the drones who inhabit these forums.
In any event... the snowmobile magazines are the best source for clutching information. Just extrapolate the information found there and apply it to ATV applications. Olaf Aaen's book is also good for theory. But if a person is looking for specific recipes for specific makes and models of machines. Mr. Aaen's book will be of no benefit unless a person takes the theories and begins their own experimentation.
The design of the CVT transmission is one of compromise with the following variables. Sheave angles of the front clutch and rear clutch, belt stretch, belt grip, belt width, primary sheave pressure, primary clutch weights/shape, secondary helix angles (straight or compounded),and secondary belt pressure. All of these factor interact with each other and changing one factor influences all of the others.
The helix senses load, (now consider a rider and passenger weight of 400 lbs, a winch, luggage pack, cooler etc compared to a 130# rider with no other weight on the machine) these two machines probably need changes to the helix for maximum overall performance. Etc. Etc.
Usually.... most changes can be made in the primary clutch with changing the weights up or down by a couple of grams and changing out the primary spring to one with a few pounds more belt pressure on the low end of the rpm range. (Change the blue/green to white and give it a try)
Out of curiosity some time go over to rec. sport. snowmobile newsgroup and ask a clutching question. It will not be unanswered and a lot of people will respond with good valid valued opinions. Snowmobilers share this information more readily than ATVers.
************************************************** *******
Consider the following post from a snowmobiler
************************************************** *******
First we need to understand a couple things.
1) Torque. A force. Think of it as how hard you push.
2) A ramp. Why did the ancients invent this? It's a brilliantly
simple force multiplier.
For example, if you wanted to put a 1000 lb refrigerator into the back
of your pickup you couldn't just lift it in. It would be too heavy.
But you *could* use a ramp and push it up. So the ramp converted
your horizontal force into a vertical one.
The angle of the ramp determines if the vertical force will be greater
or lesser than the horizontal force applied. From experience you know
that the flatter the ramp angle the easier it is to get the
refrigerator up into the truck. So a shallower angle converts the
horizontal force into a bigger vertical force.
Given these two concepts, the torque sensing clutch is easy. The
helix is the ramp. It converts some portion of the track load into a
sideways pressure on the sheaves. Consequently, when the track load
increases so does the sheave pressure. This extra sheave pressure
squeezes the belt out to a larger diameter in the clutch and creates
the downshift.
Easy, huh? But you need the answer to your next question to make
anything work...!
>..........Also how are the controls (springs,
>weights, helix, etc. ) balanced between the primary and secondary clutch
>to make the drive sheave and driven sheave work together to get optimum
>performance out of the engine.
The front clutch is RPM sensing. This means that the side force on
the sheaves is based on the RPM of the clutch. The faster the clutch
spins, the more centrifugal force is generated. The cam arms and
their profiles convert this centrifugal force into sheave side
pressure.
The back clutch is torque sensing so it converts track load into a
sheave side pressure as we discusses earlier.
The relative sheave side pressures (front versus back) determine where
the belt sits in the clutches and therefore what "gear' the
transmission is in. For example, more sheave pressure in the back
clutch pushes the belt to an outer diameter and therefore lowers the
gearing.
The various helix ramp, cam angles and springs etc are all chosen so
that at full throttle where the engine is trying to spin as fast as it
can, the resultant sheave forces equalize to put the engine in a
"gear" that loads the engine down to its peak HP rpm (say 8000RPM).
From that point, if the transmission didn't shift you can see that
increasing the track load would load the engine down and pull it off
the peak RPM. Conversely, lightening the track load would allow the
engine to over rev. In a manual transmission you compensate by
shifting gears. On a snowmobile the transmission does this
automatically.
As the track load increases, the back clutch shifts the belt to an
outer diameter. This lowers the gear ratio. If the clutch doesn't
shift out enough the engine slows down (falls off its power peak). If
the engine slows down the front clutch looses some sheave side
pressure allowing the back clutch to shift out more. This lowers the
gearing further and allows the engine to come back onto its power
peak. Conversely, if the back clutch shifted out too far (ie too low
a gear) then the engine will speed up and the front clutch will exert
more side pressure. This raises the gear ratio and pulls the engine
rpm back down to the optimum.
A lessening track load is basically just the reverse of this.
By the way, your final exam question is as follows: If I increase the
spring tension in my rear clutch but otherwise leave everything else
the same, what will the peak engine rpm do?
a) go up
b) stay the same
c) go down
Have fun!
QED
Byron Sheppard
Looks like you have just found out that it is currently in Spam wordSpam word Spam wordSpam word Spam wordSpam word Spam wordSpam word Spam wordSpam word to ignore the vast majority of questions regarding cvt clutching.
I suspect a few reasons exist for this phenomenon.
#1. The average reader doesn't have a clue what you are asking.
#2. It took so long for some people to figure out the answer they don't want to give you the answer freely.
#3. Those that do know, don't want you to know. There is too much money to be made in the sale of clutch kits (and colored springs) and the sale of other misinformation.
#4. The old timers who know the answers have moved on or been driven off by the drones who inhabit these forums.
In any event... the snowmobile magazines are the best source for clutching information. Just extrapolate the information found there and apply it to ATV applications. Olaf Aaen's book is also good for theory. But if a person is looking for specific recipes for specific makes and models of machines. Mr. Aaen's book will be of no benefit unless a person takes the theories and begins their own experimentation.
The design of the CVT transmission is one of compromise with the following variables. Sheave angles of the front clutch and rear clutch, belt stretch, belt grip, belt width, primary sheave pressure, primary clutch weights/shape, secondary helix angles (straight or compounded),and secondary belt pressure. All of these factor interact with each other and changing one factor influences all of the others.
The helix senses load, (now consider a rider and passenger weight of 400 lbs, a winch, luggage pack, cooler etc compared to a 130# rider with no other weight on the machine) these two machines probably need changes to the helix for maximum overall performance. Etc. Etc.
Usually.... most changes can be made in the primary clutch with changing the weights up or down by a couple of grams and changing out the primary spring to one with a few pounds more belt pressure on the low end of the rpm range. (Change the blue/green to white and give it a try)
Out of curiosity some time go over to rec. sport. snowmobile newsgroup and ask a clutching question. It will not be unanswered and a lot of people will respond with good valid valued opinions. Snowmobilers share this information more readily than ATVers.
************************************************** *******
Consider the following post from a snowmobiler
************************************************** *******
First we need to understand a couple things.
1) Torque. A force. Think of it as how hard you push.
2) A ramp. Why did the ancients invent this? It's a brilliantly
simple force multiplier.
For example, if you wanted to put a 1000 lb refrigerator into the back
of your pickup you couldn't just lift it in. It would be too heavy.
But you *could* use a ramp and push it up. So the ramp converted
your horizontal force into a vertical one.
The angle of the ramp determines if the vertical force will be greater
or lesser than the horizontal force applied. From experience you know
that the flatter the ramp angle the easier it is to get the
refrigerator up into the truck. So a shallower angle converts the
horizontal force into a bigger vertical force.
Given these two concepts, the torque sensing clutch is easy. The
helix is the ramp. It converts some portion of the track load into a
sideways pressure on the sheaves. Consequently, when the track load
increases so does the sheave pressure. This extra sheave pressure
squeezes the belt out to a larger diameter in the clutch and creates
the downshift.
Easy, huh? But you need the answer to your next question to make
anything work...!
>..........Also how are the controls (springs,
>weights, helix, etc. ) balanced between the primary and secondary clutch
>to make the drive sheave and driven sheave work together to get optimum
>performance out of the engine.
The front clutch is RPM sensing. This means that the side force on
the sheaves is based on the RPM of the clutch. The faster the clutch
spins, the more centrifugal force is generated. The cam arms and
their profiles convert this centrifugal force into sheave side
pressure.
The back clutch is torque sensing so it converts track load into a
sheave side pressure as we discusses earlier.
The relative sheave side pressures (front versus back) determine where
the belt sits in the clutches and therefore what "gear' the
transmission is in. For example, more sheave pressure in the back
clutch pushes the belt to an outer diameter and therefore lowers the
gearing.
The various helix ramp, cam angles and springs etc are all chosen so
that at full throttle where the engine is trying to spin as fast as it
can, the resultant sheave forces equalize to put the engine in a
"gear" that loads the engine down to its peak HP rpm (say 8000RPM).
From that point, if the transmission didn't shift you can see that
increasing the track load would load the engine down and pull it off
the peak RPM. Conversely, lightening the track load would allow the
engine to over rev. In a manual transmission you compensate by
shifting gears. On a snowmobile the transmission does this
automatically.
As the track load increases, the back clutch shifts the belt to an
outer diameter. This lowers the gear ratio. If the clutch doesn't
shift out enough the engine slows down (falls off its power peak). If
the engine slows down the front clutch looses some sheave side
pressure allowing the back clutch to shift out more. This lowers the
gearing further and allows the engine to come back onto its power
peak. Conversely, if the back clutch shifted out too far (ie too low
a gear) then the engine will speed up and the front clutch will exert
more side pressure. This raises the gear ratio and pulls the engine
rpm back down to the optimum.
A lessening track load is basically just the reverse of this.
By the way, your final exam question is as follows: If I increase the
spring tension in my rear clutch but otherwise leave everything else
the same, what will the peak engine rpm do?
a) go up
b) stay the same
c) go down
Have fun!
QED
Byron Sheppard
Sep 23, 2001 | 09:29 PM
#4
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|
Pro Rider
Joined: Aug 2001
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I can only speak out of my own experiences. I have done alot of clutch work to my own wheeler and have done work to others. I've never used a tach. I would like to have one someday but the one I want is more than just a tach. This also means that it cost more than just a tach.
To answer the question you have posted:
#1- If you are speaking of "peak engine rpm" as being the maximum rpm's that your engine will turn, then the answer would be: B
The reason being that the engine will only turn so many rpm's partly to the shear weight of the primary clutch set up. Also due to engine mods. Such as porting, pipe and carb mods and air box mods. The only way you could raise your rpm's in this case by only dueing clutch mods is to lighten the primary clutch. However, you still probably won't gain any here this way without engine mods.
#2- If you are speaking of "peak engine rpm" as being the point where the engine begins upshifting the clutch, the answer would be: A
This is what I call the shift point. This would raise because the engine now would have to exert more pressure to pull the secondary through the shift. This does raise the shift point but, not by all that much when using stock components. You would probably notice the higher rpm but it is not raised by all that much.
Thor, that has to be the BIGGEST reply I've ever seen. Did you really type all that? However, you didn't really answer any of my questions. Not that I don't appreciate what you had to say but I was aware of most of what you posted. A refresher course never hurt anyone.
By the way, what is reason for not answering any of my questions? #1, #2, #3 or #4.
Don't take that as an insult. That's not the way it was intended. I was just curious what you really know.
To answer the question you have posted:
#1- If you are speaking of "peak engine rpm" as being the maximum rpm's that your engine will turn, then the answer would be: B
The reason being that the engine will only turn so many rpm's partly to the shear weight of the primary clutch set up. Also due to engine mods. Such as porting, pipe and carb mods and air box mods. The only way you could raise your rpm's in this case by only dueing clutch mods is to lighten the primary clutch. However, you still probably won't gain any here this way without engine mods.
#2- If you are speaking of "peak engine rpm" as being the point where the engine begins upshifting the clutch, the answer would be: A
This is what I call the shift point. This would raise because the engine now would have to exert more pressure to pull the secondary through the shift. This does raise the shift point but, not by all that much when using stock components. You would probably notice the higher rpm but it is not raised by all that much.
Thor, that has to be the BIGGEST reply I've ever seen. Did you really type all that? However, you didn't really answer any of my questions. Not that I don't appreciate what you had to say but I was aware of most of what you posted. A refresher course never hurt anyone.
By the way, what is reason for not answering any of my questions? #1, #2, #3 or #4.
Don't take that as an insult. That's not the way it was intended. I was just curious what you really know.
Sep 24, 2001 | 11:48 AM
#5
Pro Rider
Joined: Oct 1999
Posts: 1,435
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Thor, that has to be the BIGGEST reply I've ever seen. Did you really type all that?
I am sure that you have heard of cut and paste[img]i/expressions/face-icon-small-happy.gif[/img]
However, you didn't really answer any of my questions. Not that I don't appreciate what you had to say but I was aware of most of what you posted. A refresher course never hurt anyone.
Yes, Elroy you are on the right track with your theory. The curve (shape)of the weight will also make a difference in the shifting properties of the primary clutch. Then there is also notching of the weight to consider for engagement points. (Hmmmm what was wrong with that)
By the way, what is reason for not answering any of my questions? #1, #2, #3 or #4. I was just curious what you really know.
Sorry, I did not realize that you were on a fishing expidition. Do not worry about my answers to your four questions. You should be concerned about the vast majority of readers who did not respond at all.
BTW question #3 was redundant and question 4 did not need a response.
Don't take that as an insult. That's not the way it was intended.
I am curious about the shape of the weight and how it affects the way the primary engages and shifts.
There are those who can extrapolate information and those who cannot.If you are looking for an exact recipe for your Polaris 300 Elroy there is none.
Now if the shape of the weights is your main concern, first familiarize your self with the dynamics of centrifigual force and rotational inertia and apply the shapes of the weights to these two theories.
The curve of the weight will determine how fast the belt moves through a particular portion of the clutch sheave.
The actual weight in grams of the shift weight determines how quickly the belt moves up the sheave overcoming side force pressure from the primary spring.
If the bulk of the weight was at the end then I would think that it would engage a little lower but then shifter really fast.
Yes it would engage at a lower rpm and the centrifugal force would try and move the belt up the sheaves faster.
If the bulk of the weight was closer to the pivot point then I would think it would have a higher engagement and shift slower.
Yes
Does this make any sence?
Yes
Does anyone out there know?
Yes
I am sure that you have heard of cut and paste[img]i/expressions/face-icon-small-happy.gif[/img]
However, you didn't really answer any of my questions. Not that I don't appreciate what you had to say but I was aware of most of what you posted. A refresher course never hurt anyone.
Yes, Elroy you are on the right track with your theory. The curve (shape)of the weight will also make a difference in the shifting properties of the primary clutch. Then there is also notching of the weight to consider for engagement points. (Hmmmm what was wrong with that)
By the way, what is reason for not answering any of my questions? #1, #2, #3 or #4. I was just curious what you really know.
Sorry, I did not realize that you were on a fishing expidition. Do not worry about my answers to your four questions. You should be concerned about the vast majority of readers who did not respond at all.
BTW question #3 was redundant and question 4 did not need a response.
Don't take that as an insult. That's not the way it was intended.
I am curious about the shape of the weight and how it affects the way the primary engages and shifts.
There are those who can extrapolate information and those who cannot.If you are looking for an exact recipe for your Polaris 300 Elroy there is none.
Now if the shape of the weights is your main concern, first familiarize your self with the dynamics of centrifigual force and rotational inertia and apply the shapes of the weights to these two theories.
The curve of the weight will determine how fast the belt moves through a particular portion of the clutch sheave.
The actual weight in grams of the shift weight determines how quickly the belt moves up the sheave overcoming side force pressure from the primary spring.
If the bulk of the weight was at the end then I would think that it would engage a little lower but then shifter really fast.
Yes it would engage at a lower rpm and the centrifugal force would try and move the belt up the sheaves faster.
If the bulk of the weight was closer to the pivot point then I would think it would have a higher engagement and shift slower.
Yes
Does this make any sence?
Yes
Does anyone out there know?
Yes
Sep 24, 2001 | 12:00 PM
#6
Pro Rider
Joined: Oct 1999
Posts: 1,435
Likes: 0
Hey Shaggy,
By the way, your final exam question is as follows: If I increase the
spring tension in my rear clutch but otherwise leave everything else
the same, what will the peak engine rpm do?
a) go up
b) stay the same
c) go down
************************************************** **
A) go up During upshift?
Would it not be the same rpm as stock at top speed
************************************************** **
The peak engine rpm would increase, because the engine rpm is not a constant and the final shift out of the secondary in a snowmobile clutch is in overdrive. On an Arctic Cat secondary clutch if the engine rpm drops down below peak power levels at final shiftout (top end), engine rpms can be increased by approximatley 200 rpm by (tightening the secondary spring) moving the spring over one hole. Top speed may not necessarily increase but the engine will be more tightly spooled.
"Would it not be the same rpm as stock at top speed?" Ever notice how some cars and trucks are faster in 4th gear than they are in 5th gear? Because they can pull a higher rpm?
By the way, your final exam question is as follows: If I increase the
spring tension in my rear clutch but otherwise leave everything else
the same, what will the peak engine rpm do?
a) go up
b) stay the same
c) go down
************************************************** **
A) go up During upshift?
Would it not be the same rpm as stock at top speed
************************************************** **
The peak engine rpm would increase, because the engine rpm is not a constant and the final shift out of the secondary in a snowmobile clutch is in overdrive. On an Arctic Cat secondary clutch if the engine rpm drops down below peak power levels at final shiftout (top end), engine rpms can be increased by approximatley 200 rpm by (tightening the secondary spring) moving the spring over one hole. Top speed may not necessarily increase but the engine will be more tightly spooled.
"Would it not be the same rpm as stock at top speed?" Ever notice how some cars and trucks are faster in 4th gear than they are in 5th gear? Because they can pull a higher rpm?
Sep 24, 2001 | 12:28 PM
#7
Thread Starter
|
Pro Rider
Joined: Aug 2001
Posts: 348
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Thor,
I was not looking for a recipe in specific for my 300 Express. I have been under the conclusion that this is probably the rarest of the 90's quads from Polaris. I have never expected anyone to know anything about this particular quad.
The numbers #1, #2, #3 or #4, were referring to your reasons why people don't reply to these clutching posts.
#1. The average reader doesn't have a clue what you are asking.
#2. It took so long for some people to figure out the answer they don't want to give you the answer freely.
#3. Those that do know, don't want you to know. There is too much money to be made in the sale of clutch kits (and colored springs) and the sale of other misinformation.
#4. The old timers who know the answers have moved on or been driven off by the drones who inhabit these forums.
The reason I posted these questions was because I was thinking of cutting some weight off my weights. I was actually looking for some insight as to what would happen if you cut weight off this spot or that spot. My thinking on what I said was mere common sence. Sometimes things require more than just common sence. I was hoping to find someone who actually knew for sure what would happen when you start modifing weights. I like to think that I am a smart person. I however don't pretend to think that I know everything. This is why I ask questions. Common sence thinking can get you far but, it doesn't make you an expert.
I was not looking for a recipe in specific for my 300 Express. I have been under the conclusion that this is probably the rarest of the 90's quads from Polaris. I have never expected anyone to know anything about this particular quad.
The numbers #1, #2, #3 or #4, were referring to your reasons why people don't reply to these clutching posts.
#1. The average reader doesn't have a clue what you are asking.
#2. It took so long for some people to figure out the answer they don't want to give you the answer freely.
#3. Those that do know, don't want you to know. There is too much money to be made in the sale of clutch kits (and colored springs) and the sale of other misinformation.
#4. The old timers who know the answers have moved on or been driven off by the drones who inhabit these forums.
The reason I posted these questions was because I was thinking of cutting some weight off my weights. I was actually looking for some insight as to what would happen if you cut weight off this spot or that spot. My thinking on what I said was mere common sence. Sometimes things require more than just common sence. I was hoping to find someone who actually knew for sure what would happen when you start modifing weights. I like to think that I am a smart person. I however don't pretend to think that I know everything. This is why I ask questions. Common sence thinking can get you far but, it doesn't make you an expert.
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Sep 24, 2001 | 03:48 PM
#8
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Joined: Oct 1999
Posts: 1,435
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LOL this is really something. The printed word is deceptive at times and lacks the body english, grins, and other available clues from a personal conversation. I was thinking about your second response before, while relaxing in the garage and thought Duh! His original intention was to gain different outside perspectives on his own theories, thereby either reinforcing or causing thought trains to go in a different direction previously not considered. Sorry.
AAEN Performance sells a jig for grinding weights just like you are contemplating. This jig allows for the custom shaping of up to 4 weights all at the same time. Have I used one? Nope.
I was looking for information like this myself awhile back. I had the idea that if a person knew the power and torque curve of a particular engine that weights could be purchased/reground to exactly match the torque curve of the engine maximizing to the ground power with a given load. To date the power curves of the Fuji 500 4 stroke have not been published from a reliable source. The trick is to have secondary clutch downshift to the peak of the torque band under load and then ride the power curve to the maximum output the engine is capable of without over-reving. Sorry I missed your tongue in cheek humor. It must be Monday [img]i/expressions/face-icon-small-wink.gif[/img]
From what I have seen so far, the factories don't miss optimum clutching by much and only small changes are required to maximize performance for a particular given situation. I'll stand by now and let the thread roll. Good luck.
AAEN Performance sells a jig for grinding weights just like you are contemplating. This jig allows for the custom shaping of up to 4 weights all at the same time. Have I used one? Nope.
I was looking for information like this myself awhile back. I had the idea that if a person knew the power and torque curve of a particular engine that weights could be purchased/reground to exactly match the torque curve of the engine maximizing to the ground power with a given load. To date the power curves of the Fuji 500 4 stroke have not been published from a reliable source. The trick is to have secondary clutch downshift to the peak of the torque band under load and then ride the power curve to the maximum output the engine is capable of without over-reving. Sorry I missed your tongue in cheek humor. It must be Monday [img]i/expressions/face-icon-small-wink.gif[/img]
From what I have seen so far, the factories don't miss optimum clutching by much and only small changes are required to maximize performance for a particular given situation. I'll stand by now and let the thread roll. Good luck.
Sep 24, 2001 | 07:44 PM
#9
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Joined: Jul 1999
Posts: 580
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I tend to disagree with your statement that the factories don't miss by much. It all depends on what you mean. From a performance standpoint they miss by a lot, for utility work, it doesn't matter much, except for driveability. Much more can be obtained with weight specific clutch tuning over a stock setup. Also rollers tend to offer "considerably" better backshifting and quicker upshifting to improve performance.
The term "weight specific" has not been mentioned before and is the critical element of clutch tuning that separates the winners from also-rans. There has been too much emphasis placed on high engagement systems that had previously worked well on 150+ hp drag race sleds. ATV's don't need this type of clutching and in fact, it is a deteriment to good consistent performance.
Getting back to the original question . . . the shape of the flyweights are critical since the weight of the flyweight is controlled by the shape, and where it's at. This can be easily controlled. The point is to follow the rule of straight line shiftout and top end to the limit. It's a little harder on atv's because of the lack of power/torque from these meager engines. You must also know where your engine makes power.
In general the closer the weight is to the fulcrum point, the more it will affect the shiftout. Too little weight low and you rev past the optimum shiftout point. Understand that you must have the proper engagement spring in to start with. That has the most affect on engagement. Too little weight in the middle of the flyweight and you will shiftout, gain more rpm, and then the rpm will decrease on top. If the flyweight is too light on the end it will tail off and gain rpm on the very top rpm limit. So elroy, the end of the flyweight affects the top end shiftout, not the low end engagement. If you have heavier overall weights, it will engage a little lower, but the shiftout will not be affected, as long as the mid-top weight is still right.
All of this can be controlled, but it takes a considerable amount of time to test, adjust, and test, and adjust, etc. Every time you make performance improvements that improve the rpm range and where your engine makes hp you will need to adjust to get maximum hp to the rubber. It takes a very fine digital scale to make minute adjustments that will reward you with superior performance.
A good starting point it to get a tach to see where you are at right now. You want an "exact" straight line from shiftout to max top end. A funny thing about clutching . . . it is not a seat of the pants type of tuning that you can feel. Generally when the bike starts to get real smooth and seems slower, it is then real quick and faster by the clock. Smooth is quick and your clutch will run better and cooler than ever.
There is so much to be gained by properly clutching a well-tuned engine, that has been overlooked and promoted like hype from the speed merchants just to get people to buy their products. Everyone wants a machine that will wheelie and look impressive (to their friends) on takeoff, spin the tires, etc . . . I think it's better to not be noticed on takeoff and smile later on, after the finish line. There are lots ( well, a few anyway) of well-built engines, but very, very few machines that are clutched properly. They all have the sled-head syndrome.
All that power and nothing to do but spin, spin, spin . . . tsk, tsk, tsk.
Trader Jack
www.godigital-design.com/schultzmotorsports
The term "weight specific" has not been mentioned before and is the critical element of clutch tuning that separates the winners from also-rans. There has been too much emphasis placed on high engagement systems that had previously worked well on 150+ hp drag race sleds. ATV's don't need this type of clutching and in fact, it is a deteriment to good consistent performance.
Getting back to the original question . . . the shape of the flyweights are critical since the weight of the flyweight is controlled by the shape, and where it's at. This can be easily controlled. The point is to follow the rule of straight line shiftout and top end to the limit. It's a little harder on atv's because of the lack of power/torque from these meager engines. You must also know where your engine makes power.
In general the closer the weight is to the fulcrum point, the more it will affect the shiftout. Too little weight low and you rev past the optimum shiftout point. Understand that you must have the proper engagement spring in to start with. That has the most affect on engagement. Too little weight in the middle of the flyweight and you will shiftout, gain more rpm, and then the rpm will decrease on top. If the flyweight is too light on the end it will tail off and gain rpm on the very top rpm limit. So elroy, the end of the flyweight affects the top end shiftout, not the low end engagement. If you have heavier overall weights, it will engage a little lower, but the shiftout will not be affected, as long as the mid-top weight is still right.
All of this can be controlled, but it takes a considerable amount of time to test, adjust, and test, and adjust, etc. Every time you make performance improvements that improve the rpm range and where your engine makes hp you will need to adjust to get maximum hp to the rubber. It takes a very fine digital scale to make minute adjustments that will reward you with superior performance.
A good starting point it to get a tach to see where you are at right now. You want an "exact" straight line from shiftout to max top end. A funny thing about clutching . . . it is not a seat of the pants type of tuning that you can feel. Generally when the bike starts to get real smooth and seems slower, it is then real quick and faster by the clock. Smooth is quick and your clutch will run better and cooler than ever.
There is so much to be gained by properly clutching a well-tuned engine, that has been overlooked and promoted like hype from the speed merchants just to get people to buy their products. Everyone wants a machine that will wheelie and look impressive (to their friends) on takeoff, spin the tires, etc . . . I think it's better to not be noticed on takeoff and smile later on, after the finish line. There are lots ( well, a few anyway) of well-built engines, but very, very few machines that are clutched properly. They all have the sled-head syndrome.
All that power and nothing to do but spin, spin, spin . . . tsk, tsk, tsk.
Trader Jack
www.godigital-design.com/schultzmotorsports
