Date: 28-03-24  Time: 21:14 pm

Author Topic: misfire @ 5k - 8k rpm  (Read 2608 times)

74eldiablo

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misfire @ 5k - 8k rpm
« on: 11 April 2021, 09:41:34 am »
The last time i rode my bike back in late september it ran sweet no problems, in mid october i decided to clean the bike it fired up ok but when i rode it a little bit i noticed there was a misfire around 5k - 8k.. i put this down to the fact i had not disconnected the battery and i needed charging that why it was misfiring.


The battery has been on the optimate for well over a month now, went back the garage yesterday hooked up the battery and tried to start it didnt start straight away, i left it 5 mins and it fired up and was ticking over without any problems once i had warmed it up i again had a little ride and the same thing is still there, bike has done 33k.


I changed the plugs back in the UK when i bought the bike to ngk iridium they have done maximum 1000 miles,
I need to get this fixed as a divorce bill means sadly my bike has to go, anyone any ideas.


Thanks in advance

Dave48

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Re: misfire @ 5k - 8k rpm
« Reply #1 on: 11 April 2021, 10:09:12 am »
Just a couple of thoughts:
When you put your bike away in the autumn did you add any fuel stabiliser to the tank?
When you press the starter button does the engine turn over at normal speed or slowly & reluctantly?
If you can rule out degraded fuel- modern petrol doesnt last long unused-and your battery is in good condition then I would suspect spark plug LEADS & CAPS. Depending on the age of these thenyour sparksmay be tracking or earthing out rather than firing the cylinders.
Damp conditions in storage may aggravate this problem.

BBROWN1664

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Re: misfire @ 5k - 8k rpm
« Reply #2 on: 11 April 2021, 11:03:12 am »
Check the plug caps are on properly and not arcing
Another ex-Fazer rider that is a foccer again

darrsi

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Re: misfire @ 5k - 8k rpm
« Reply #3 on: 11 April 2021, 11:28:34 am »
What does it run like under 3000rpm, or at low speeds?
Do a quick TPS check and see if it's in the correct position, they gradually break down and a misfire at any speed is one symptom, but the main symptom would be rough or jerky running at low speeds where you'd need to use more clutch and throttle to compensate. It's something that will take a minute to check, and needs to be ruled out.


Also, when was the last time you changed/cleaned your air filter? A badly clogged paper air filter for example will eventually affect running. K&N filters tend to be a lot more forgiving as they let more air through but they can still get dirty as well.
« Last Edit: 12 April 2021, 05:57:17 am by darrsi »
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74eldiablo

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Re: misfire @ 5k - 8k rpm
« Reply #4 on: 12 April 2021, 08:36:54 am »
Thanks for the replies, i would say it is definitely an electrical issue.


I didn't add fuel stabiliser ... but at the time i last started and noticed the misfire the fuel was 2 weeks old, but i agree old fuel will not help the matter.


I need to go back to the garage and inspect the leads,caps etc, I have ruled out the plugs due to the fact they are only 1000 miles old,however i will still pull them and inspect.


ok so i guess it a case of starting at the plugs and working backwards, so i'm guessing the suppressor caps are screw on ones?? so is it just a case of chopping a bit off and winding them back on?
I'm hoping that i dont need new caps as money is tight right now.


Regarding the TPS it has those tamperproof screws on them is there away around this??







« Last Edit: 12 April 2021, 08:47:43 am by 74eldiablo »

74eldiablo

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Re: misfire @ 5k - 8k rpm
« Reply #5 on: 12 April 2021, 08:50:41 am »
What does it run like under 3000rpm, or at low speeds?
Do a quick TPS check and see if it's in the correct position, they gradually break down and a misfire at any speed is one symptom, but the main symptom would be rough or jerky running at low speeds where you'd need to use more clutch and throttle to compensate. It's something that will take a minute to check, and needs to be ruled out.


Also, when was the last time you changed/cleaned your air filter? A badly clogged paper air filter for example will eventually affect running. K&N filters tend to be a lot more forgiving as they let more air through but they can still get dirty as well.


It runs ok below 3k, idles fine.
New air filter 500 miles ago


Thanks for the advise from everyone i will do the TPS and fingers crossed it is this.




celticbiker

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Re: misfire @ 5k - 8k rpm
« Reply #6 on: 14 April 2021, 10:06:30 pm »
If start by ditching those iridium plugs, I've had them break down in under 1000 miles.
Only buy plugs from a dealer or m and p  (somewhere reputable) as there are tons of fakes out there on eBay.
Then check caps, leads and coils.
There are only a few things in the ignition system to cause a miss fire.
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darrsi

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Re: misfire @ 5k - 8k rpm
« Reply #7 on: 15 April 2021, 05:35:53 am »
If start by ditching those iridium plugs, I've had them break down in under 1000 miles.
Only buy plugs from a dealer or m and p  (somewhere reputable) as there are tons of fakes out there on eBay.
Then check caps, leads and coils.
There are only a few things in the ignition system to cause a miss fire.


He didn't actually mention Ebay, but i have had moody ones off there before that started faltering after a month. I won't use anything but Iridium now though.
I buy from these people who are legit, and reasonably priced. https://www.gsparkplug.com/


But as far as a misfire, there's more than you might think to cause it.
Bad fuel, water in fuel, air leak, blocked air filter, TPS breaking down/faulty, dodgy/knackered plugs, HT caps not screwed on tightly, HT leads need chopping at the ends as wires are pushed into outer casing, coils breaking down, unbalanced carbs, etc.
It's not as straightforward as you'd imagine, plus it could always be a combination of things too. For example if you balance the carbs with any of the other things listed not right then you are opening up a new world of pain.
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darrsi

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Re: misfire @ 5k - 8k rpm
« Reply #8 on: 15 April 2021, 05:49:59 am »
Thanks for the replies, i would say it is definitely an electrical issue.


I didn't add fuel stabiliser ... but at the time i last started and noticed the misfire the fuel was 2 weeks old, but i agree old fuel will not help the matter.


I need to go back to the garage and inspect the leads,caps etc, I have ruled out the plugs due to the fact they are only 1000 miles old,however i will still pull them and inspect.


ok so i guess it a case of starting at the plugs and working backwards, so i'm guessing the suppressor caps are screw on ones?? so is it just a case of chopping a bit off and winding them back on?
I'm hoping that i dont need new caps as money is tight right now.


Regarding the TPS it has those tamperproof screws on them is there away around this??


You would only adjust the TPS if it was in the wrong position, then you would need a T25 size Torx security key, the one with the hole in the middle.
But it needs to simply be checked first to see if the needle lands on the 5000rpm mark. If it does then you leave it well alone.
If it isn't then you can adjust it until it's correct, but from previous experience you then need to check it again a few days later. If it has moved off the 5000rpm position again then you have a faulty TPS.
And if it ever did turn out to be deemed faulty, DO NOT buy a used one. If you do you could be buying one that is 20+ years old and could fail on you the next day.


Mind you, you say you're selling it so i don't suppose that would really bother you too much.   


https://www.ebay.co.uk/itm/1-SECURITY-TORX-PIN-HOLE-TX25-T25-ALLEN-L-SHAPE-KEY-WITH-HOLE-FOR-PIN-90-DEG/302010493346?hash=item46513a69a2:g:VekAAOSwDk5T-4gr
« Last Edit: 15 April 2021, 05:54:21 am by darrsi »
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darrsi

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Re: misfire @ 5k - 8k rpm
« Reply #9 on: 15 April 2021, 05:53:28 am »
When you say you cleaned it, was it a bucket and sponge job, or did you use a jet wash?
A jet wash can get water into places that you really don't want it to, and due to the current climate it may be still be trapped somewhere.
Just a thought.....
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celticbiker

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Re: misfire @ 5k - 8k rpm
« Reply #10 on: 15 April 2021, 07:36:35 pm »
I'll put my flag in the ground. 😝
It's a Yamaha, if the obvious plugs, fuel and filter are eliminated (and should have been first) then it's a coil.
Stake your guesses now.
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darrsi

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Re: misfire @ 5k - 8k rpm
« Reply #11 on: 16 April 2021, 05:22:58 am »
I'll put my flag in the ground. 😝
It's a Yamaha, if the obvious plugs, fuel and filter are eliminated (and should have been first) then it's a coil.
Stake your guesses now.


My guess........Sold As Seen  :lol
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red98

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Re: misfire @ 5k - 8k rpm
« Reply #12 on: 16 April 2021, 09:31:58 am »
nasty DARRSI  :lol ...my pennies worth, i would go for electrics, be surprised if its the coil`s CELTICBIKER...but that does depend on how bad the stutter is ...74ELDIABLO  does the bike pull through the stutter and run well up to the red line ?


my money`s on a bad connection somewhere,maybe moisture corroding a connector and hopefully a cheap but time consuming fix. shame you have to sell the fazer  :(
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celticbiker

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Re: misfire @ 5k - 8k rpm
« Reply #13 on: 16 April 2021, 10:27:06 am »
Let battle commence.... 🤕
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red98

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Re: misfire @ 5k - 8k rpm
« Reply #14 on: 16 April 2021, 10:42:59 am »
 :lol
One, is never going to be enough.....

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Re: misfire @ 5k - 8k rpm
« Reply #15 on: 01 May 2021, 08:09:25 am »
I had the same issue, turned out my HT leads were getting wet. I only noticed as i was getting a nasty electric shock when fiddling with the tickover screw.


Just a possibility (if you haven't already sorted it)

74eldiablo

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Re: misfire @ 5k - 8k rpm
« Reply #16 on: 22 May 2021, 04:06:29 pm »
Thanks to everyone who replied to my post, turns out it was the plug caps, changed to NGK SD05F and everything is again perfect, I have to say that this part of the forum (fzs600) is full of wise knowledgable bikers who offer simple straight advise and usually the first few posters are bang on the money, you are all a credit to bikers... no matter who you are... bikers help bikers, and in my book thats a real brotherhood.

It will be a real shame to sell my bike due to a lawyers fees, however everything happens for a reason and i have enjoyed being part of this with you guys.
« Last Edit: 22 May 2021, 04:07:16 pm by 74eldiablo »

darrsi

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Re: misfire @ 5k - 8k rpm
« Reply #17 on: 22 May 2021, 07:45:54 pm »
Good to hear that not only was it a simple fix, but an inexpensive one too.  :)
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