Date: 26-08-19  Time: 05:32 AM

Author Topic: Miss fires if running in traffic  (Read 182 times)

Whomightyoube

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Miss fires if running in traffic
« on: 15 June 2019, 09:29:11 AM »
My FZS600 runs fine if I start on choke and set of on an open road. The choke can go in pretty soon, before I get to the end of our road. I can then pull out into the. Main road, no problem but If I encounter traffic early on then it miss fires on 3rd cylinder and does not recover. Otherwise it is as smooth as you like at all revs, pulling away etc. What's going on?

darrsi

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Re: Miss fires if running in traffic
« Reply #1 on: 15 June 2019, 09:46:42 AM »
For starters you shouldn't need any choke at all in this climate, it should only be needed in very cold weather. And i don't think i've ever actually ridden the bike with the choke still on, it must run like shite doing that alone?


How do you know it's misfiring on the 3rd cylinder?


First thing i would do would be to start with the basics.


New IRIDIUM plugs, they work much better than standard, they cost a few more quid but will last for many years.
If you want to maybe check the plugs first, swap 3 & 1 over and see if the issue moves with it.
Is the air filter good? Again i would personally change a standard one for a K&N, so a tad dearer but the last filter you'll ever buy for the bike as it's washable.
More people are born because of alcohol than will ever die from it.

darrsi

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Re: Miss fires if running in traffic
« Reply #2 on: 15 June 2019, 09:56:54 AM »
My guess is your "smooth as you like" understanding is not as accurate as you would think.
There are many more things that can cause rough running, like a faulty TPS, carbs badly out of sync, blocked jets, etc, so you have to start with the obvious first.


But only do one thing at a time, otherwise you'll not know what the issue was if it suddenly starts behaving after doing two or more things together.
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Whomightyoube

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Re: Miss fires if running in traffic
« Reply #3 on: 15 June 2019, 10:13:15 AM »
Thanks for your reply.


I was just wondering if the symptoms on their own are indicative of a basic problem. I have done some investigations of my own.


I have historically not had to use choke much at all on this bike but I I try to start with no choke now the cylinder 3 does not fire at all. It starts smoothly on choke and runs fast. I put the choke in pretty quickly after starting off.


I know it is cylinder 3 as the down pipe is colder or completely cold if I start with no choke. Have got new plugs. Sparks seem good. Swapped coils etc, always cylinder 3. Swapped over the two leads which fire at the same time. Re prepared the lead ends.


I have cleaned carbs thoroughly including transfer lines and replaced bits on carb 3.Basic kit with new O rings gasket and float valve. Float in good condition.


I have done compression test and cylinder 3 is down but still over 100 psi. I am thinking that it may be valve clearances or sticking valve? Would this cause this intermittent fault?


When I run out on an open road all down pipes are the same temperature and it runs smoothly even at low revs.

darrsi

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Re: Miss fires if running in traffic
« Reply #4 on: 15 June 2019, 12:16:28 PM »
Take out plug Number 3 and see if it's wet or dry after starting the bike for a minute, preferably when cold.


Wet means electrical, and dry means fuel issue.


Was it happening before you changed the plugs?
Where did you buy your plugs from and which ones are you using?
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His Dudeness

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Re: Miss fires if running in traffic
« Reply #5 on: 15 June 2019, 07:09:06 PM »
Thanks for your reply.


I was just wondering if the symptoms on their own are indicative of a basic problem. I have done some investigations of my own.


I have historically not had to use choke much at all on this bike but I I try to start with no choke now the cylinder 3 does not fire at all. It starts smoothly on choke and runs fast. I put the choke in pretty quickly after starting off.


I know it is cylinder 3 as the down pipe is colder or completely cold if I start with no choke. Have got new plugs. Sparks seem good. Swapped coils etc, always cylinder 3. Swapped over the two leads which fire at the same time. Re prepared the lead ends.


I have cleaned carbs thoroughly including transfer lines and replaced bits on carb 3.Basic kit with new O rings gasket and float valve. Float in good condition.


I have done compression test and cylinder 3 is down but still over 100 psi. I am thinking that it may be valve clearances or sticking valve? Would this cause this intermittent fault?


When I run out on an open road all down pipes are the same temperature and it runs smoothly even at low revs.
I think you've done enough to rule out spark. If giving it some choke improves running at idle and low revs to me that sounds like the pilot circuit is blocked in carb 3. You could try turning the mixture screw out a 1/4 or 1/2 turn on carb 3 and see if that improves things. That would probably only be masking the problem not fixing it but if doing that improves things that would give you clear evidence that the problem is a blockage in the pilot circuit
I printed out DUDE'S instructions...even on paper they are pretty confusing...Has he been INGESTING some MIND ALTERING substance......???

daviee

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Re: Miss fires if running in traffic
« Reply #6 on: 16 June 2019, 11:51:49 AM »
carbs need cleaned  as above the pilot circuit is blocked you should never need to ride one of these  on choke