Z900RS

Please login or register.

News: A big welcome to all new members !



Author [NL] [FR] [ES] [DE] [SE] [IT] [NO] [MY] Topic: Re: twitchy throttle article  (Read 43345 times)

0 Members and 2 Guests are viewing this topic.

Offline Ben

  • Z900RS Pro
  • ***
  • Posts: 119
  • Country: ch
Re: twitchy throttle article
« Reply #90 on: May 16, 2018, 09:25:53 PM »
*Originally Posted by rodsky77 [+]
So, you think this issue can only be resolved by flashing the ECU?
*Originally Posted by Y2K18 [+]
It's really strange how some bikes are affected and others are not...
Hm you two just gave me a thought. How does the ECU determine the cut-off point and after that, the fuel amount? Is it a throttle valve angle sensor? Throttle lever sensor? Air flow meter? If it's a combination of two sensors, and they weren't aligned well, that would result in more jerkiness I imagine. And it might come with the possibility for easy modification, say, if you could disable the sensor that determines the cutoff and let the ECU calculate the fuel amount based on the MAF readings only. Maybe someone with access to the workshop manual can figure out what the ECU is measuring exactly?

Offline rodsky77

  • Z900RS Member
  • **
  • Posts: 54
  • Country: ch
Re: twitchy throttle article
« Reply #91 on: May 16, 2018, 10:16:05 PM »
I'm afraid that I'm not technical enough in these matters  :027:
But, I did read somewhere that the issue comes from the fact that the mixture is too lean in idle in order to make the bike Euro4 compliant, and then once you pull the throttle, the mixture becomes too rich too quickly.
Some people have been saying that a mapping change in the ECU would actually resolve the issue.

At the same time, the Z900 is also Euro4 compliant and it does not have this problem.
Perhaps the way the RS is built - more torque and HP in the lower rev range than the Z900, maybe that makes a difference.

Would be interesting to find out what's the real cause of this issue.

*Originally Posted by Ben [+]
Hm you two just gave me a thought. How does the ECU determine the cut-off point and after that, the fuel amount? Is it a throttle valve angle sensor? Throttle lever sensor? Air flow meter? If it's a combination of two sensors, and they weren't aligned well, that would result in more jerkiness I imagine. And it might come with the possibility for easy modification, say, if you could disable the sensor that determines the cutoff and let the ECU calculate the fuel amount based on the MAF readings only. Maybe someone with access to the workshop manual can figure out what the ECU is measuring exactly?

Offline flynbulldog

  • Z900RS Pro
  • ***
  • Posts: 367
  • Bike: lotobikes
  • Town / City: Greensboro NC
  • Country: us
Re: twitchy throttle article
« Reply #92 on: May 17, 2018, 01:03:43 PM »
*Originally Posted by rodsky77 [+]
So, you think this issue can only be resolved by flashing the ECU?

I do. I think the "fuel cut" is the issue and needs to be turned off in the programing. 

Offline Y2K18

  • Z900RS Master
  • ****
  • Posts: 636
  • Bike: Kawi Z900RS
  • Town / City: Raleigh, NC
  • Country: us
Re: twitchy throttle article
« Reply #93 on: May 17, 2018, 02:23:33 PM »
Another post may have hit on it.... You guys with issues, is there any free play in your throttle cables or is it tight??
On my VFR, I installed taller bars, which made the cables tighter. This caused a jerky throttle. Once I adjusted some free play back in she went back to silky smooth.   

Offline flynbulldog

  • Z900RS Pro
  • ***
  • Posts: 367
  • Bike: lotobikes
  • Town / City: Greensboro NC
  • Country: us
Re: twitchy throttle article
« Reply #94 on: May 17, 2018, 08:34:56 PM »
*Originally Posted by Y2K18 [+]
Another post may have hit on it.... You guys with issues, is there any free play in your throttle cables or is it tight??
On my VFR, I installed taller bars, which made the cables tighter. This caused a jerky throttle. Once I adjusted some free play back in she went back to silky smooth.

My cables had about an 8th turn of free-play from the factory. Someone on here said that was too much so I tightened them up to about half of that. It didnt make any difference in the fuel cut. I'm going to put them back to where they were stock. I can tell you without any trepidation - the issue my bike is having has nothing to do with the cables.

Offline Y2K18

  • Z900RS Master
  • ****
  • Posts: 636
  • Bike: Kawi Z900RS
  • Town / City: Raleigh, NC
  • Country: us
Re: twitchy throttle article
« Reply #95 on: May 17, 2018, 08:40:25 PM »
*Originally Posted by flynbulldog [+]
My cables had about an 8th turn of free-play from the factory. Someone on here said that was too much so I tightened them up to about half of that. It didnt make any difference in the fuel cut. I'm going to put them back to where they were stock. I can tell you without any trepidation - the issue my bike is having has nothing to do with the cables.

I'll check mine tonight to compare. Anything is possible with same spec vehicles not acting the same. My GF and her mom bought identical (except color) Z28's back in the early 90's. The GF's was much faster feeling!!
« Last Edit: May 17, 2018, 08:41:30 PM by Y2K18 »

Offline Smilinjack

  • Z900RS Member
  • **
  • Posts: 48
  • Town / City: Nottingham
  • Country: gb
Re: twitchy throttle article
« Reply #96 on: May 17, 2018, 09:46:27 PM »
*Originally Posted by flynbulldog [+]
My cables had about an 8th turn of free-play from the factory. Someone on here said that was too much so I tightened them up to about half of that. It didnt make any difference in the fuel cut. I'm going to put them back to where they were stock. I can tell you without any trepidation - the issue my bike is having has nothing to do with the cables.

VFR Vtec? Well known for on/off throttle issues. The Chadda mod sorted mine out.  :002:
Everyone you meet is fighting a battle you know nothing about. Be kind, always.

Offline Y2K18

  • Z900RS Master
  • ****
  • Posts: 636
  • Bike: Kawi Z900RS
  • Town / City: Raleigh, NC
  • Country: us
Re: twitchy throttle article
« Reply #97 on: May 17, 2018, 11:27:41 PM »
*Originally Posted by Smilinjack [+]
VFR Vtec? Well known for on/off throttle issues. The Chadda mod sorted mine out.  :002:

No I have the real VFR, with gear driven cams!!  :008:
Yes V-Tec's, especially early ones, were terrible. The Power Commander helps quite a bit.

Offline Y2K18

  • Z900RS Master
  • ****
  • Posts: 636
  • Bike: Kawi Z900RS
  • Town / City: Raleigh, NC
  • Country: us
Re: twitchy throttle article
« Reply #98 on: May 17, 2018, 11:32:12 PM »
*Originally Posted by flynbulldog [+]
My cables had about an 8th turn of free-play from the factory. Someone on here said that was too much so I tightened them up to about half of that. It didnt make any difference in the fuel cut. I'm going to put them back to where they were stock. I can tell you without any trepidation - the issue my bike is having has nothing to do with the cables.

If you discount the looseness in the grip (it rocks back and forth) there is no play in my cables. I'll be in Mebane on Saturday but not sure the weather will be bike friendly. If you're interested, PM me your phone number I made a 9 second video moving the throttle.
« Last Edit: May 17, 2018, 11:55:59 PM by Y2K18 »

Offline gnoub51

  • Z900RS Member
  • **
  • Posts: 43
  • Bike: Z900 RS
  • Town / City: Frederick, Maryland
  • Country: us
Re: twitchy throttle article
« Reply #99 on: May 18, 2018, 04:10:27 AM »
Adding my two cents so I can get a notification about the ‘fix’ when available.

There’s no doubt the bike is just a little too on/off. Makes for a ‘bumpy’ ride if the road is not smooth. At least at first. I’m sure you can adjust to anything.  But, I think a re-map will solve the problem.  And I’d rather have that then trying to ’fix’ my throttle hand.

I love this bike. Make no mistake about that.  But I will take advantage of a new tune when available.  Especially since I see Akropovic headers and a better flowing air filter in my future. And need the tune for those mods.

Gary

« Last Edit: May 18, 2018, 04:11:32 AM by gnoub51 »
2018 Z900 RS - 'Kaito'
2016 Yamaha Black FZ07 - ‘Leona’