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Offline orangeblue

Jumpy/ Jerky at low speeds
« on: July 29, 2016, 02:43:16 PM »
I was hoping this would work its self out during break in, but almost 200 miles on my Uforce800 and its still bad.  From takeoff, its really hard to feather the pedal to keep it from jerking or bucking until it gets up to speed.  Reverse seems like its 5MPH or nothing. 
I adjusted the throttle cable to take out some of the slack, but it didnt help. Anyone have this issue with theirs?

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Offline NMKawierider

Re: Jumpy/ Jerky at low speeds
« Reply #1 on: July 29, 2016, 03:03:00 PM »
Some have reported that the peddle spring is too easy and causes unsteady placement. We have a How To for the Zs that fixes that. Others have reported or found a problem with their wet clutch return springs that causes issues. And yet others found their hand brake setting was a bit too tight causing the drive train to kinda lock and release at slow speeds. Just stuff to look at.
2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | 9.7" GPS | Bandit Springs Rear & Gen-3 Shocks Front

My Videos On YouTube

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Offline wooddude

Re: Jumpy/ Jerky at low speeds
« Reply #2 on: August 02, 2016, 09:35:43 PM »
sort of. I sometimes get the herky jerks on launch in forward, and it happens more often in reverse. My son has a Kawasaki and he sometimes gets it too. Some throttle jockying helps.
2015 UForce 800
30 Cree Bar Light

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Offline NMKawierider

Re: Jumpy/ Jerky at low speeds
« Reply #3 on: August 02, 2016, 09:49:21 PM »
sort of. I sometimes get the herky jerks on launch in forward, and it happens more often in reverse. My son has a Kawasaki and he sometimes gets it too. Some throttle jockying helps.
If you could do a video of it doing this ...you know..from the side, maybe we could get an idea where to look. Mine does it some in reverse creeping. 
2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | 9.7" GPS | Bandit Springs Rear & Gen-3 Shocks Front

My Videos On YouTube

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Offline gfmoto

Re: Jumpy/ Jerky at low speeds
« Reply #4 on: August 04, 2016, 08:51:33 PM »
Yup, mine too. Maybe the throttle body on these don't move smoothly or something. Idk, I think it's me sometimes not paying attention to peddle pressure. Never have that issue if you drive it like you stole it.
2015 ZForce 800EX
32" light bar
2-4" spots
Custom Cv guards
DIY 1/2 windshield
UNI air filter
DIY rear window
BOSS ATV 28. 450W speakers
Alpena Rock Lights (tough pods)
2" RZR Bracket lift
Roof extensions
27" Maxxis Corranado Tires
Alpena RGB rock lights
SuperATV Rocksliders
1/2 Doors w/custom paint and graphics

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Offline REDRIDER

Re: Jumpy/ Jerky at low speeds
« Reply #5 on: January 17, 2017, 08:29:46 AM »
I think it's just the nature of the wet clutch set up its either on or off not much for slip, but that's a good thing IMO, just hard to get used to.

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Offline Z8rider

Re: Jumpy/ Jerky at low speeds
« Reply #6 on: January 17, 2017, 08:49:06 AM »
Taking "slack" out of the throttle cable is only going to leave you with an improperly adjusted throttle cable. A LOT of very good mechanics seem to think that throttle cable free play on a machine like this is adjusted with the pedal at rest, if it has a little free-play, its good, right? Nope... The cam where the throttle cable connects on the thorttle body, there are two corresponding tabs that stops the throttle from opening past wide open throttle. If those contact each other and the accelerator has not reached its stop position and you keep pressing the pedal, you are just stretching the cable at that point and risk snapping the cable.

Long story short, when the accelerator is all the way to the floor, the cable needs to be adjust to allow a small gap shown in the picture.


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Offline Z8rider

Re: Jumpy/ Jerky at low speeds
« Reply #7 on: January 17, 2017, 09:04:36 AM »
A little explanation on how the engagement works. The wet clutch engagement is more of an "on" or "off" type of engagement with a very little window between the two. Perhaps 50 RPM, this is where your jerking is taking place. Most people end up doing this, slowly depress the accelerator, machine starts moving a tad faster than they want, they aren't steady in backing off and then the wet clutch has barely disengaged, which means its also very close to engaging... ergo... jerking when the give it a tad more gas to start moving. It is nearly impossible to "feather" between the two. The best case is to just be steady with the foot and operate in that little window when you are trying to creep along. An engaging style CVT system (like the cv tech on the 500HO), the belt itself, along with the belt having some give/or slippage on the CVT makes the "on" and "off" a lot less abrupt.

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Offline REDRIDER

Re: Jumpy/ Jerky at low speeds
« Reply #8 on: January 17, 2017, 02:44:13 PM »
if absolutely necessary to inch along something, I will use the foot brake and double pedal it to keep it from lurching. Only do this sparingly and when really necessary to avoid unwanted wear on clutch components or belt.

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Offline davidpaul

Re: Jumpy/ Jerky at low speeds
« Reply #9 on: January 18, 2017, 01:58:30 PM »
My Zforce used to jump and buck like a bitch, mine was caused by a very lean mixture setup from the factory, when I pressed the throttle to pull away she would rev enough for the wet clutch to engage then she would hesitate enough for the clutch to drop out causing jerky jumpy, One way to get over this is to step on the gas hard when pulling away from stationary, I've now fitted a Dobeck EJK and disconnected the O2 sensors which aloud me to adjust the mixture at the lower end of the rev range, I'm a fussy person and like her to be smooth at low speed, I know have almost no hesitation and no jerking at all (just sharing my experience)
2015 Zforce 800, Dr Pulley weights and sliders, Dobeck EJK, Innovate Motorsports AFR gauge,
Custom exhaust outlet, Ramair foam air filter, Led light bars, Modified air intake, CRD a-arm guards

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Offline Max2015

Re: Jumpy/ Jerky at low speeds
« Reply #10 on: February 28, 2017, 06:20:38 AM »
I just had my Uforce in for work and the dealer noticed it was jumpy and he put a Z8 ECU in it and fixed the problem. He said that was the fix from CFMOTO at no charge.