Date: 28-03-24  Time: 11:11 am

Author Topic: Throttle Jerky At Low Revs ?  (Read 3573 times)

Neon Knight

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Throttle Jerky At Low Revs ?
« on: 20 March 2016, 02:34:45 pm »
I have had my Gen 1 stored away for the winter and have been relying on his ever reliable older sister a FZS 600 to get me back and fore to work during the bad weather. Usually after a good wipe down and clean I have no problems with the Gen 1 after his annual hibernation. This year has proved to be different. The bike has 14,000 on the clock and is generally in good condition apart from the small winter rust spots. After charging the battery I decided to take it out for a blast and was dismayed to find a quite poor throttle response from about 2,500 up to about 5,000, then it gives a cough and splutter and pulls as strongly as ever. I have done a little internet reading and have come to the conclusion it's either a carb problem or a possible stuck or sticking Exup. I am a bit of a tinkerer but I am no mechanic. I have read that usually an error message usually comes up on the tacho if the exup is playing up but as yet i have not seen one. Any idea's-suggestions would be appreciated. Cheers  :'(

PieEater

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Re: Throttle Jerky At Low Revs ?
« Reply #1 on: 20 March 2016, 04:46:49 pm »
The rev range that you are having the problem with is right in the middle of the EXUPs operating range. Servicing the EXUP and checking the cable tension should be part of your maintenance routine so if you haven't done this yet it's about time http://www.cartestsoftware.com/fz1/exupmaintenance.html

Neon Knight

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Re: Throttle Jerky At Low Revs ?
« Reply #2 on: 20 March 2016, 06:56:56 pm »
Thanks mate, I have had my suspicions that it was probably the EXUP, I just wanted a second opinion before I attempt to fix it. It looks a fairly straightforward operation without the need of 3 years of mechanical college courses. Is there any tricky bits i should be aware of whilst servicing ? Much appreciated  :)

windscreenman

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Re: Throttle Jerky At Low Revs ?
« Reply #3 on: 20 March 2016, 07:05:46 pm »
May also be pilots blocked or 1 of how do you store it over winter fuel wise do you use a conditioner  usually helps to stop blocking pilots
Objects in your mirrors may be stupider than they look
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PieEater

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Re: Throttle Jerky At Low Revs ?
« Reply #4 on: 20 March 2016, 08:04:15 pm »
Thanks mate, I have had my suspicions that it was probably the EXUP, I just wanted a second opinion before I attempt to fix it. It looks a fairly straightforward operation without the need of 3 years of mechanical college courses. Is there any tricky bits i should be aware of whilst servicing ? Much appreciated  :)
No tricky bits just follow Pat's guide, have a container for all the parts as you take them off and after cleaning refit using lots of copper grease or even better ceramic grease. I printed off Pat's guide and referred to it for the first couple of services but after that it's straightforward enough. It may not be the EXUP that's the problem as it's unlikely anything has happened since you last rode the bike to stop it working properly (barring a mouse chewing through a cable) but it's a fairly simple job to do and one that you shouldn't neglect.

mick chiz

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Re: Throttle Jerky At Low Revs ?
« Reply #5 on: 21 March 2016, 04:19:28 am »
ive a fazer 1000 gen 1 and its been off the road since October last year,my exup valve had seized up(14/03/2016)took the cover off and moved it by hand and its fine again.
i hope yours is as simple as that.
i cant strip mine down as the bolts holding it in are broken and undrillable too.they need the gas axe,but i cant be arsed.

Neon Knight

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Re: Throttle Jerky At Low Revs ?
« Reply #6 on: 22 March 2016, 07:46:48 pm »
Looked at the casing and it looks like the previous owner snapped off or lost 2 of the 3 casing bolts  :'( Hope he hasn't mangled the 2 mounting bolts for the EXUP itself as they dont look too clever. I have sprayed them with lots of "Silkopen" and have left them overnight in the hope they will come off without too much drama. Hoping this will do the trick. Fingers crossed and wish me luck  :eek

Falcon 269

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Re: Throttle Jerky At Low Revs ?
« Reply #7 on: 22 March 2016, 10:00:29 pm »
Sticking EXUP would give tacho error code.  If it's maladjusted, it would have been that way before the winter lay-up.

I'm thinking stale fuel and carb blockages.  However, overhaul the EXUP anyway and if that doesn't cure the problem, try some Redline carb cleaner (search on ebay) to see if that will save you a trip into the carbs.

steeeve66

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Re: Throttle Jerky At Low Revs ?
« Reply #8 on: 23 March 2016, 01:42:21 pm »
i had a similar prob which turned out to be the fuel pump - I tried everything to solve it but got nowhere until I read about Bike magazine's FZR they raced at the Isle of Man a couple of years back. They did the same (tried everything) until finally swapping the fuel pump with a unit from an R1, the problem was solved. Not a cheap item (200 odd quid i think?) so make sure you eliminate everything else first..
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