2014 YZ450F - Using Mapping to Reduce Engine Braking?


15 replies to this topic
  • mx4u2c

Posted March 29, 2016 - 08:31 AM

#1

I have heard pro mechanics talk about changing the mapping as a means of reducing engine braking.  Does anyone know what general direction you would go on the maps, and where (throttle position, etc.)?

 

I have a programmer full of maps that I have pulled from various sources and have found a couple that I like - however, I am just curious as to where you would change the mapping if your goal is to reduce the feel of engine braking, or if this even makes sense.

 

I'm sure I will get responses like "go into the turn a gear higher" or "use the engine braking to your advantage" but that is not my question or the feedback that I am looking for...just wondering if mapping can be used to alter and affect engine braking...thanks!  



  • Bremer120

Posted March 29, 2016 - 08:44 AM

#2

This is with no experience, but it would need to be tuned at a closed throttle parameter because that is where engine braking is experienced. Even a slightly cracked throttle takes away engine braking. How to tune it out or if it's possible I don't know.

Edited by Bremer120, March 29, 2016 - 08:50 AM.


  • grayracer513

Posted March 29, 2016 - 09:03 AM

#3

I think this is the subject of a growing myth.  The only means by which engine braking can be reduced would be to raise the idle speed. 

 

And I still have no idea why people get so uptight about it.  Engine braking is your friend.  The complete lack of it is one of the things I hate about two-strokes.



  • mx4u2c

Posted March 29, 2016 - 09:23 AM

#4

Hey Greyracer513 - Thanks for the feedback.  I have heard mechanics talk about this and it piqued my interest since I have no knowledge or experience with it.

 

Coming from 30+ years of riding two strokes and having had four strokes that feel like they have less engine braking than this current bike, I guess it is just something I have grown accustomed to liking less of -- since it seems illogical to me to "tune it out" with mapping, I just wanted to put it out there for some dialogue in the event I was missing something.

 

I guess the flip side would be to ask if you can "add more" engine braking with mapping.  Regardless, I just wanted to see if anyone had knowledge or experience with anything in this regard. 



  • grayracer513

Posted March 29, 2016 - 09:41 AM

#5

I don't see how it can be influenced except by dialing the idle up or down, or waiting until mid-turn to downshift, which can be awkward and inconvenient.  It's a function of engine compression, cam timing, and geometric factors involving the crank, rod and bore.



  • CSAR FE

Posted March 29, 2016 - 10:20 AM

#6

You can always put a Rekluse in it if you don't like the engine braking. It doesn't necessarily make the engine braking go away per se, as its a characteristic of the four strokes, but when you let off the throttle the bike basically freewheels. 



  • mx4u2c

Posted March 29, 2016 - 10:58 AM

#7

Hey CSAR FE -

 

That's actually a good idea...I know someone with the same bike that has a Rekluse, it will obviously be an easy comparison to ride his bike and see if I notice the difference.

 



  • grayracer513

Posted March 29, 2016 - 01:10 PM

#8

Once again, a Rekluse auto clutch DOES NOT FREEWHEEL when you let off the gas.  The reason simply is that the engine is coupled to the trans by the clutch, and is therefore turning faster than the engagement speed, so it stays engaged, and you have normal engine braking. 

 

The only time you don't is if you pull the clutch and let the engine fall back to idle, where the clutch will release.  If you then let go of the lever, the engine will remain uncoupled until something speeds it up to the engagement speed again, like a blip of the throttle.

 

Clutches that do wholly or partially freewheel are called "back torque limiting", or sometimes, "slipper" clutches.  These drive all or part of the plate stack through either a roller clutch or a sprag clutch.  Depending on the design, they reduce the driveline snatch associated with releasing the throttle at high RPM, or freewheel completely.  A Rekluse is not one of these.



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  • CSAR FE

Posted March 29, 2016 - 02:34 PM

#9

I stand corrected.

  • TN Dirt Rider

Posted March 29, 2016 - 07:40 PM

#10

The guys at Chaparral Moto seem to think the Rekluse reduces engine braking. In the MXA article where they rode a YZ450F built by Chap they had a Rekluse installed stating that it reduced engine braking.

  • grayracer513

Posted March 29, 2016 - 08:41 PM

#11

Ever ridden one?



  • TN Dirt Rider

Posted March 30, 2016 - 04:52 AM

#12

Ever ridden one?


I'm not sure if you are asking me, but I have a '14 450F without a Rekluse. I've owned 3 bikes with Z-starts, an 03 YZ250F, an 07 KTM 300 XC-W, and my currently owned 08 YZ295. Installed the z-start in the two Yamahas and it was already in the KTM when I got it.

My 450 was geared up one tooth in the back when I bought it so I haven't ridden it with stock gearing. The engine braking is pronounced, but I'm getting used to it and learning to use it to my advantage.

I've got considerably more riding time on my 2 stroke, both with and without the Rekluse, and I would certainly say that it has less engine braking now than it did before. I've only been back riding for 4 years after 20 plus years off, so still a novice.

  • grayracer513

Posted March 30, 2016 - 06:31 AM

#13

Any reduction in engine braking above about 3000 RPM when running a Rekluse is entirely perceptual and imaginary.  The clutch clamps up solidly at speeds above that, and has no idea what's being done with the throttle.  It "knows" only about engine speed, and if, when turning say, 6000, you release the throttle, the engine is still turning 6000, and the clutch will stay engaged until something makes the engine turn slower than lock up speed, or until it slows to that speed and releases.  Once you understand how it operates, you can see that it isn't capable of reducing engine braking in any way. 



  • TN Dirt Rider

Posted March 30, 2016 - 07:57 AM

#14

Any reduction in engine braking above about 3000 RPM when running a Rekluse is entirely perceptual and imaginary.  The clutch clamps up solidly at speeds above that, and has no idea what's being done with the throttle.  It "knows" only about engine speed, and if, when turning say, 6000, you release the throttle, the engine is still turning 6000, and the clutch will stay engaged until something makes the engine turn slower than lock up speed, or until it slows to that speed and releases.  Once you understand how it operates, you can see that it isn't capable of reducing engine braking in any way. 

Not arguing, just curious....I would think that Larry Brooks is pretty knowledgeable on bike setup, so why do you think they would say it helps with engine braking if it is physically impossible to do so??  Some incentive provided by Rekluse to help them sell more clutches??

 

From my perspective, perhaps it is not so much a pure reduction in engine braking, per se, that it is providing, but instead a much better level of clutch engagement versus my ham handed manual working of a clutch.  Maybe I'm not feeling the engine braking as much because the Rekluse is feathering the clutch just enough instead of me doing a poor job of it myself.  I don't know...I'm not technically very knowledgeable I just know what I feel by the seat of my pants.

 

I've loved every Rekluse I used, but I'm actually considering not putting on in my 450 because they do tend to neuter the bottom end in my experience.  One of the things I like about the 450 is being able to go slower through a corner and still be able to clear the next jump.  I'm afraid a Rekluse would dampen that capability as I feel it does have that affect.

 

Sorry to divert somewhat the original topic from tuning out the braking.



  • motohead13

Posted March 30, 2016 - 08:42 AM

#15

Mapping has nothing to do with engine braking

  • grayracer513

Posted March 30, 2016 - 10:31 AM

#16

Not arguing, just curious....I would think that Larry Brooks is pretty knowledgeable on bike setup, so why do you think they would say it helps with engine braking if it is physically impossible to do so??  Some incentive provided by Rekluse to help them sell more clutches??

 
Can't speak for him.  From my own experience and technical understanding, I can't see why anyone would say such a thing unless it's the magic feather phenomena again.
 

From my perspective, perhaps it is not so much a pure reduction in engine braking, per se, that it is providing, but instead a much better level of clutch engagement versus my ham handed manual working of a clutch.  Maybe I'm not feeling the engine braking as much because the Rekluse is feathering the clutch just enough instead of me doing a poor job of it myself.  I don't know...I'm not technically very knowledgeable I just know what I feel by the seat of my pants.

 
Engine braking occurs when the throttle is released at speeds above idle, right?  The Rekluse clutch engages the clutch from a slight drag to a full lock up starting at just over idle (the engagement point you set with the release spring selection) to up at about 3000-3500, at which point it's completely clamped down because of the rotational speed of the clutch, and at which point it will hold the full power of the engine turning against the highest gear it has.  Once above that speed, if the clutch won't slip under power, it's certainly not going to slip even slightly when things turn around and the wheel is spinning the engine. 
 
However, if you operate within that narrow range of low engine speeds between the start of engagement and full lock up, the clutch will slip to some degree both on and off throttle, so you may find that when poking around things slowly that the clutch actually will release when you back off, but you'd be moving at less than 10 MPH, so I don't see the "evils of engine braking" working against you there.
 

I've loved every Rekluse I used, but I'm actually considering not putting on in my 450 because they do tend to neuter the bottom end in my experience.  One of the things I like about the 450 is being able to go slower through a corner and still be able to clear the next jump.  I'm afraid a Rekluse would dampen that capability as I feel it does have that affect.

Depends on the setup and how you run through the corner.  Right off of idle, it will take a little bit of the snappy, jerky, immediate response out, but that should bother trail riders more than MX.  I can't see how the clutch would not be fully engaged at the speeds you'd be running in a turn.  The bike should respond as it does now.

 

People use the clutch in corners way too much on big 4 strokes anyway, when they should be using the throttle to control cornering and exits.  With all that power, they just don't need the help that peaky pingers do. 
 







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