How I eliminated the twitchy throttle

[D.A.]

1 hour ago, Pursuvant said:

...  it's his design ... I will send it to D.A. for his tweeks and then he can publish, cause this is D.A. all the way ...

I appreciate the vote of confidence! However, I have no patent or expertise when it comes to throttle tamers, which lots of companies already manufacture. Your ideas, opinions and experience are just as valid as mine so please feel free to self-publish any modifications you design.

[Pursuvant]

Well, if my measurements are correct, it suggests a reason for the "twitchy" stock throttle. Below is just a mock up of my measures, I'm using your pic D.A.  of the R6 tube, but imagine this is a stock MT-07 tube, and the red lines are the angle that the cable entering the throttle housing is pulling on the tube....

At idle, when you first start to roll on the throttle, the cable is pulling at an angle where it is no where near making contact with the cam it is supposed to wrap around. It's instead in a position where it's pulling on the acceleration cable like a cam that was much larger than the actual cam (news to me but D.A. already gets it from his work).

Imagine the drawing above (as a representation of the OEM MT-07 tube) slowly rotating clockwise as you throttle up. At first the tube is acting like a "quick twist", it's pulling the acceleration cable faster than expected (can you say twitchy?), and as you continue rolling on the throttle it begins to settle down until at about 10% (just a guess from observation) the cable finally makes contact with the cam it's supposed to wrap around. At that point the throttle will start operating at a steady pull rate based on the diameter of the cam, and it will continue to operate at the same rate of pull to wot.

I expect that if the throttle cable was in the 10% position shown above when you are at idle, there would not be a "twitchy" stock bike throttle. Just a steady continuous pull rate as the cable wraps around the cam diameter.

On order for me is a new "stock" MT-07 grip assemble (throttle tube) as well as an R6 tube. I have an idea how to tame that first 10% stock tube behavior for anyone who doesn't want the quick twist R6. No promises, just playing here. And chemo messes with my memory and perception so don't hold me to anything here please. Don't take any actions based on anything I have suggested here. In fact don't ever do any of my suggested mods, they will kill you and give you foot fungus.

And then I will do D.A. 's design of an R6 quick twist with low throttle opening tamed a bit.

 

[D.A.]

8 hours ago, Pursuvant said:

... Below is just a mock up of my measures ...

Nice!

I recut my cam today based on your input regarding drilling an additional hole. This time I cut it super-close to the tube barrel to get the smallest possible radius. I’ll post more details when I have time. Tested it in the bike and it seems to work great. 
 

Edited December 6, 2020 by D.A.

[Pursuvant]

How I got my measures, I marked the spot where the acceleration cable exits the cable, inside the top housing half-piece...

and the I hook the acceleration cable to the tube, and hold the tube/top half housing together as if it was fully assembled, but without the bottom half of the housing...

and then holding the assy in my left hand, I can rotate/accelerate & decelerate the throttle as if it was completely assembled, and I can watch & mark my other important measure points and angle of the cable as it approaches the cam, and how much rotation is needed before the cable "touches down" on the cam. That angle of approach of the cable and where it first touches down on the cam is a big deal for explaining why the lack of precision in opening/low throttle positions...

 

Edited December 6, 2020 by Pursuvant

[Pursuvant]

On 12/6/2020 at 1:27 AM, D.A. said:

Nice!

I recut my cam today based on your input regarding drilling an additional hole. This time I cut it super-close to the tube barrel to get the smallest possible radius. I’ll post more details when I have time. Tested it in the bike and it seems to work great. 
 

Oh ya, now you're cooking! I think we still have to think about how to get that cable to already be touched down on (the reduced cam cut) in your picuture, when you are still at idle. So as soon as you start to roll the throttle on, the cable is already touching down at the smallest radius of your modified cam.

Edit - For the stock throttle tube (not R6 tube), I do a cable swap to get adjustment back at throttle body adjuster. I put the decel cable in the original accel cable hole, that's available because accel cable goes in new drilled hole. This cable swap also rotates stock tube to improve just off idle smoothing.

So far I don't see anything that compromises safety in the design, if the implementation is nice & clean.

Edit - Best tools, you can use two hacksaw blades held together in your hand to cut groove, they are just the right width. And you can flip them upside down (teeth up) an wrap with 400 grit emery paper to sand work clean. Makes cutting groove slow and precise.

Edited December 13, 2020 by Pursuvant

[jkrueger13]

I've had the same issues with twitchiness.  I had the stock r6 throttle tube which was great for getting to WOT.  I'm now trying the Motion Pro Rev2 throttle equipped with the progressive cam reel, which I just installed.  This should hopefully reduce the jerkiness when applying throttle mid-corner.  Also sent the ECU back to 2WDW to make adjustments for smoothness.  They said now my fuel economy will be terrible, which is not a concern of mine.

I'll also tighten the chain, which is a good idea to reduce drivetrain twitchiness.  Moving in the right direction!

Since I'm in WI, I won't be able to test these changes for a while...

[D.A.]

1 hour ago, jkrueger13 said:

... I'm now trying the Motion Pro Rev2 throttle equipped with the progressive cam reel ... 

... Also sent the ECU back to 2WDW to make adjustments for smoothness...

I'm anxious to hear your reactions after riding with the Motion Pro Rev2!

In regards to 2WDW, what adjustments did they tell you they could make? I'm curious because they told me there is nothing they can do to smooth out off/on throttle twitchiness beyond what they did in the initial flash.

[jkrueger13]

5 hours ago, D.A. said:

I'm anxious to hear your reactions after riding with the Motion Pro Rev2!

In regards to 2WDW, what adjustments did they tell you they could make? I'm curious because they told me there is nothing they can do to smooth out off/on throttle twitchiness beyond what they did in the initial flash.

I’ll keep you posted on the throttle
 

Excerpt from email with 2wdw:

“From a mapping perspective, if the bike is going to be a 100% track machine, then we can certainly richen up the throttle transition portions of the mapping and have you disconnect the stock O2 sensor to soften up the initial "hit" of the immediate torque that these engines make. It will never feel like your R6, but we can make it smoother than it is now! We don't recommend doing this on a street bike, as the fuel economy will take a significant hit.”

I’m optimistic the new throttle and reflash are enough!

[Pursuvant]

13 hours ago, jkrueger13 said:

I'm optimistic the new throttle and reflash are enough!

Keep working that angle, but for folks (like me) that don't want to disconnect O2 and run fat, I have good news about making the stock throttle assembly mellow out for just off idle throttle openings- to stop the jerk. And D.A. is working over an R6 quick twist to tame it.

Edited December 7, 2020 by Pursuvant
Speeeallinng horibla

[D.A.]

The photo above shows my latest version (the same one I posted a few days ago) and the shot below shows what it looks like on the bike. (I rolled back part of the rubber grip to make it easier to see what’s happening.)

Notice that the cable (above) is not touching the large portion of cam when in the closed position. It is only touching the small-radius section. But once rotated about 5 degrees, the large part of the cam makes contact with the cable and pulls it at the normal, faster rate you get with the stock R6 cam. This brief period of delay allows the cable to wrap around the cam at its smallest radius long enough to mellow out the throttle twitchiness.

 

Edited December 9, 2020 by D.A.

[Pursuvant]

Big big grin here  In Texas there's a sayin, "closer to the bone the sweeter the meat". Translation, you cut that accel cable end hole so close to the underlying bar, you have created a tamer with better modulation (smoother) than Graves or MotionPro.

Major kudos D.A. you are the man! And that prototype looks better than most commercial finished product. Just outstanding, when can I order mine? Hahahaha

 

Edited December 9, 2020 by Pursuvant
sPElLINg horibla

[Pursuvant]

Here's the prototype tube using the stock MT-07 throttle tube, for building a t-tamer.

I tortured this stock tube, drilled and sawed new hole so deep you can feel the saw teeth on inside tube diameter, but I wanted to find out "how good (smooth) is the resolution possible with this tube?"

Almost cut the smooth resolution groove so deep it's almost all the way thru too, and broke a cam tab, and didn't sand smooth, and yada yada yada

But I did one thing only like a champ. I rode for 3 hours today in Houston in 70 degree full sunshine on this tube, and it's got the beans - smoothing beans. Proof of concept is solid, I have a new stock tube and R6 tube arriving Friday, I'll try not to destroy them

***Cable swap thingy  used up the cable adjuster at throttle bodies***, but I can use the cable adjuster on the accel cable at the handlebar to get this centered again at the main adjuster.

Edit***Wrong, swapping decel cable end into the original accel tube hole gives cable back to the adjuster****

 

Edited December 9, 2020 by Pursuvant

[Dennis.Halmstad]

NICE!!!!!!!

Now when its "finished" how would this end up in amount of degrees from 0-100% in relation to stock and r6?

[D.A.]

On 12/9/2020 at 1:57 AM, Dennis.Halmstad said:

... how would this end up in amount of degrees from 0-100% in relation to stock and r6? ...

@Dennis.Halmstad: since you referenced the R6 tube rather than the FZ tube, I assume you are addressing me rather than @Pursuvant 

If so, here are the approximate stats:

Stock FZ07 cam = 90°

Stock R6 cam = 60°

My latest R6 mod = 75°

Edited April 8, 2021 by D.A.

[Dennis.Halmstad]

@D.A. Yes you are correct! My excitement made me miss out on the quotes

 

Then this mod turns the quick action r6 tube to a progressive tube with high precision on low throttle and slightly quicker action.

And to create this precision but to keep 60° opening we would need to add material to the cam.

Is this even possible or would we run out of room in the housing?

 

Would all of this we want be able to get done by modifying or create a new part on the other end of the cables?

A new wheel at the throttle bodies?

 

Edited December 9, 2020 by Dennis.Halmstad

[Pursuvant]

6 hours ago, Dennis.Halmstad said:

NICE!!!!!!!

Now when its "finished" how would this end up in amount of degrees from 0-100% in relation to stock and r6?

D.A. and I have a "trick" to reduce total rotation back closer to 60 degrees to reach wot, but it's a last step in building a tamer. Would work for stock tube and R6 tube tamer, will be working with D.A. on it, I haven't tried it yet.

The limit on reducing tamer rotation is a fixed amount because reducing rotation uses up accel cable and you can run out of cable adjustment at throttle bodies adjuster/pulley wheel. Also limited by the throttle housing at handlebar.

I may order a custom cable to get back to R6 tube wot at 60 degrees rotation. That may be doable, but I'm trying to do tamer for $0 total cost.

Edited December 9, 2020 by Pursuvant

[Pursuvant]

3 hours ago, Dennis.Halmstad said:

@D.A.  A new wheel at the throttle bodies?

 

I ran into this problem on stock tube. Solution was to move the decel cable end from it's original decel hole in cam into the original accel hole that is now available, because we moved the accel cable end into our new drilled hole.

Works on stock cam tube with smaller radius, I still have adjustment room at the throttle bodies adjuster/pulley. Should work to give even more adjustment room with R6 tube I think.

 

Edited December 9, 2020 by Pursuvant

[D.A.]

1 hour ago, Dennis.Halmstad said:

... high precision on low throttle and slightly quicker action.

... to keep 60° opening we would need to add material to the cam.

... would we run out of room in the housing?

... create a new wheel at the throttle bodies?

1) Correct. I have to twist my modified R6 throttle further than normal when first rotating it to get through the abrupt off/on transition. After that the cam profile instantly reverts to the original R6 diameter and feel. 

2) Yes, if you can figure out a way to build up the surface of the stock R6 cam, you can increase engine speed exponentially as you continue to twist the throttle and reduce the amount of rotation required to reach WFO. 

3) I don’t know whether or not the FZ cable housing can accommodate a larger cam. Try building it up with tape or something as a test and let us know what you discover!

Some the aftermarket throttle tamers — like Motion Pro’s — come with a new housing and cable to accommodate their custom cams. And the Graves website I listed earlier says you have to cut out the stops in the stock housing to accommodate their progressive cam:

Progressive Throttle Tube ZX10 ZX6 R1 R6 R3 FZ09 FZ10 XSR900 MT-10 Graves Motorsports

---

Graves Motorsports R1 + R6 + R3 + FZ09 + FZ10 + ZX10 + ZX-6R + MT09 +...

Please note the Graves compatibility list does not include the FZ/MT-07 or XSR700 but does include the 2020 Tenere 700 and 2006+ R6, which suggests it probably fits our bikes as well. 

4) Brilliant idea about changing the shape of the butterfly pulley wheel instead! It would be hard to fabricate compared to simply shaving down the cam on a throttle tube but seems like it would achieve the same effect. 

[D.A.]

To be clear, the 4 tweaks I made to mitigate the snatchy throttle response (namely, increase idle speed, tighten chain, remove cable slack and alter cam profile [or alternately, buy a prefab throttle tamer]) were done after I had the ECU flashed by 2WDW. Although I feel the flash was of little to no benefit in eliminating twitchiness, it was nonetheless one of the steps taken in the process and therefore might be a foundational requirement for anyone hoping to emulate these results. 

But people interested in attempting this have nothing to lose by making the 4 tweaks first then deciding if flashing is warranted. 

Edited December 11, 2020 by D.A.

[Pursuvant]

A word about tools for this mod.

The stock MT-07 throttle tube (Black) is softer plastic than the R6 tube (white) (at least it is on my XSR7 variant).

Both can be modified easily with simple tools. I use 2 hacksaw blades held in my hand for groove cutting (18 teeth per inch seems about right). Then I turn the blades upside down and fold 400 grit emery cloth sand paper over the 2 blades held together, and smooth the cutting between the 2 "tabs" on the cam. For the groove outside of the tabs (it's more accessable) I finish the grooves with a thread file, that creates a nice "v" groove shape. Edge of a metal file should work too.

Drilling, start with a much smaller bit than the final 1/4" bit. Work your way up to the 1/4" with a couple of progressively larger sizes. Always pay close attention to keeping the hole from becoming an "oval". The tube tries to push the bit away from the desired hole location.

[Pursuvant]

On 12/10/2020 at 6:51 AM, D.A. said:

 the 4 tweaks I made

How about we add this to your four tweeks for a "gen 2" model?

 

We might be able to get the quicktwist back, this model of your killer curve rotated back by moving the new accel drill hole, maybe we go from 78 degrees to a quicktwist of about what,  65 degrees? You would be so close you would think it was an unmodified R6 tube, until you felt the improved FI throttling...

What do you think D.A. ? I've got an R6 tube, are there any problems you see ?

And how far to extend smoothing? I extended my stock tube prototype all the way to where it was generally experienced as blending in with the rise in torque curve around 4K. I'm thinking I want to try a shorter range, get smoothing experience only just off idle and transform to quicktwist. Solve the FI twitch/jerk, and get right into the quicktwist R6.

EDIT - i just realized this probably saves nothing, only a little gain if the new accel hole is closer to the decel hole. It's just a visual trick that does nothing. Still takes the same amount of cable to wrap around that curve. Only a change in the shape of the curve can get back degrees of rotation, or a change in the range of throttle opening you want to smooth....

Edited December 15, 2020 by Pursuvant

[D.A.]

I like where you’ve placed the new hole! As you noted in your edit, WHERE the hole is has nothing to do with the number of degrees required to reach wide open. Full rotation is based instead on the distance the cable travels around the profile’s progressive radiuses.  

No, I like the new location because it utilizes more of the plastic canyon used to guide the cable and keep it running straight. Plus, preserving the extra plastic means your design has more structural integrity than mine.  

My only addition is in regards to something not yet pictured: the access slot needed to install the accelerator cable. (See tweak below to your photo.) You should cut that slot adjacent to the decelerator hole rather than the original accelerator hole to maintain an unbroken, round surface upon which the cylinder at the end of the cable can rest:

 

One note about drilling the new hole: As you mentioned previously, it’s hard to drill the hole exactly where you want it. That’s because the outside edge of the tube has a raised ring about as thick as a hair that causes the drill bit to scootch out of position. To neutralize this issue, I sanded the edge of the tube flat before drilling:

 

I used my Dremel saw / sander for this task but you could just as easily use a piece of 2x4 wrapped in fine grit sandpaper:

 

Next I used a hole punch and hammer to create a starter hole, then started the drilling sequence, beginning with the smallest drill bit I had and gradually progressing up to the final 1/4” bit. 

[Pursuvant]

24 minutes ago, D.A. said:

I like where you’ve placed the new hole!

 

That's great post on the trickiest parts of this mod. I did cut away some material before I drilled the stock tube to keep the drill from getting pushed, but it didn't have the same ring needing cutback, it was just the tube.

Only question with new hole location is will I be in the money on the cable adjuster? We'll see

Will be following your examples for the R6 tube, after I'm done having some fun ripp'in around on it just the way it is. I should have gone R6 6 mos ago when I got bike.

Thx for cool mod D.A.

Edited December 15, 2020 by Pursuvant

[D.A.]

On 12/15/2020 at 6:06 PM, D.A. said:

... I like the new location because it utilizes more of the plastic canyon used to guide the cable and keep it running straight. Plus, preserving the extra plastic means your design has more structural integrity than mine. ...

On second thought, maybe that’s not the best spot to drill the hole. When a slot is added to install the cable, the result will be an island of plastic attached by a relatively thin peninsula of material. You could cut a slot on just one side rather than both to retain some of the strength but it still might be preferable to have a more solid block of plastic supporting the load-bearing edge of the cylinder on the end of the accelerator cable. 

Edited December 17, 2020 by D.A.

[Dennis.Halmstad]

Might be an idea to fill in the old hole with a glue gun or something and then recut the wire path?