Date: 12-08-22  Time: 15:34 pm

Author Topic: fzs 600 carburettors  (Read 8589 times)

kebab19

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Re: fzs 600 carburettors
« Reply #25 on: 24 January 2016, 11:45:38 am »
It may be that one of the rubber diaphragms is being / has been pinched upon previous reassembly.  Look for any signs of creasing or indentation and make sure the little o-ring is present and in place. Unfortunately as soon as you reassemble the carb tops, it's out of sight, so you can't see if it's in the correct position or becoming twisted as you screw the carb top screws down.
Sometimes they can be straightened out, but if they're old or gone a bit brittle then replacement is the best solution.   

Hmm... Wemoto are charging £44 for each single diaphragm:
http://www.wemoto.com/bikes/yamaha/fzs_600_fazer/98-99/picture/carburettor_diaphragm/

Another possibility (which I experienced on my 350LC) is that the carb diaphragm has been put in the wrong way, and by that I mean which way the lower part is facing.  It may need to be turned around 180 degrees. On the LC it was the carb body itself but different carb design, same principle.

No idea how mechanically minded or patient you are, so you may wish to just get a second set of carbs off ebay, flush them out and try them instead.  Indeed, it may well prove a cheaper solution....

joebloggs

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Re: fzs 600 carburettors
« Reply #26 on: 24 January 2016, 12:35:56 pm »
I always check the diaphragm by sucking on the port on the rear of each carb. You can see if they are all seated and when you suck on the port you should hear the slide lift. Check each one several times making sure it seats correctly when it returns
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unfazed

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Re: fzs 600 carburettors
« Reply #27 on: 24 January 2016, 01:44:59 pm »
Did you check all float heights. Clear plastic pipe on the drain hole and up the side, ignition on for pump to prime and fill the floats.   

rsvphil

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Re: fzs 600 carburettors
« Reply #28 on: 24 January 2016, 11:12:40 pm »
I removed the carbs again and checked everything over snd all seemed good. Reassembled and got the bike running a dusted the the idle and was satisfied I'd cured the problem. However after I came back to the bike a couple of hours later it wouldn't fire and hsnt fired once since.

unfazed

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Re: fzs 600 carburettors
« Reply #29 on: 24 January 2016, 11:38:27 pm »
Sounds like a lack of fuel, is the fuel pump actually pumping, not just making noise? Did you turn the tap on?

If the tap is on fill the tank about half way, prop it up to and bypass the pump (not the filter) to rule it out as an issue.

With the tank half full and propped there will be enough pressure to fill the carbs and run the engine

rsvphil

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Re: fzs 600 carburettors
« Reply #30 on: 24 January 2016, 11:43:59 pm »
Pump seems to be working fine and the carbs seem to have fuel in the float bowls.

crickleymal

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Re: fzs 600 carburettors
« Reply #31 on: 27 January 2016, 05:45:22 pm »
Mine was doing something similar. It would be fine in the morning when starting and would run fine all the way to work (50 miles on the motorway). But go to start it in the evening and it would run for 2 seconds then cut out. It would then take up to half an hour to get it restarted. If you got it to catch pumping the throttle seemed to be the only way to keep it running,

It's just been into the shop for valve clearances and new carb rubbers (cos the old ones were horrible). So far it seems to start much better although I haven't tried it on a run to work yet. The valve clearances were a bit tight too (25k miles). My money's on the carb rubbers for the starting issues. Mind you I had a diesel van which would be a bugger to start but would run fine once started. That was closed up valve clearances too.
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rsvphil

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Re: fzs 600 carburettors
« Reply #32 on: 29 February 2016, 10:21:00 pm »
Little update guys. Stripped the carbs out again and reset all the pilot screws. Reassembled and bike fired straight up. Wasn't running properly hunting quite a lot with a delay on the throttle. Basically slow to respond to input of the throttle also seemed to stick a bit before the revs dropped. After letting it run for a good ten minutes switched it off and left it for 20 mins. Came back out and it started up straight away. Left for 2 hours wouldn't start and now back to square one doesn't fire at all.

darrsi

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Re: fzs 600 carburettors
« Reply #33 on: 01 March 2016, 06:24:28 am »
Little update guys. Stripped the carbs out again and reset all the pilot screws. Reassembled and bike fired straight up. Wasn't running properly hunting quite a lot with a delay on the throttle. Basically slow to respond to input of the throttle also seemed to stick a bit before the revs dropped. After letting it run for a good ten minutes switched it off and left it for 20 mins. Came back out and it started up straight away. Left for 2 hours wouldn't start and now back to square one doesn't fire at all.


As you're clutching at straws now, try the bike on the centre stand with the side stand up.
My bike has just developed an annoying problem with the side stand switch, it will start one minute and not the next whilst on the side stand, but ping to life no problem and run fine with the stand up.
Still waiting for my replacement switch to arrive at the moment, but as i know the cause it's not such a problem any more and i can easily get around it.
Symptoms were not starting at all until battery was virtually flat, got jump lead started and got it running then it cut straight out with the side stand down in neutral a few minutes later, then refused to start again, until i tried it on the centre stand alone and it became happy again.
Degreased the general area as best as i could at night time around the switch then slapped WD40 everywhere to make sure the cut out piston thingy worked freely in and out, which it did.
Then days later it would consider starting, with the odd backfire, but as soon as i got the sidestand up there was no problem at all, and when i got to work and put the stand down with the bike in neutral it now carries on running fine?


Never know, it may be the same problem, it's not something i've ever encountered on any bike i've had before so it was a new one for me.


I knew it wasn't the carbs because issues with them normally involve a splutter or fart before pegging out, whereas this problem cut the engine instantly dead when it was running.
« Last Edit: 01 March 2016, 06:26:38 am by darrsi »
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rsvphil

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Re: fzs 600 carburettors
« Reply #34 on: 20 March 2016, 09:39:37 am »
Definitely not Sidestand switch the bike is on a table. The bike only starts snd runs when I strip and rebuild the carbs. But once left for a while she won't fire again until carbs are removed rebuilt and refitted.

crickleymal

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Re: fzs 600 carburettors
« Reply #35 on: 22 March 2016, 10:36:11 am »
It couldn't be the floats or the float valve sticking could it?
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unfazed

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Re: fzs 600 carburettors
« Reply #36 on: 22 March 2016, 07:12:15 pm »
A friend of mine rang me with an issue on a BMW R1150GS he was working on, it was very similar to your problem, might start and if it did start it would not rev, then when it would run it would be fine for a few miles then stop and not restart. It had a good spark so we brought it back to the garage and it started. :groan
I spent  a day with him and we checked the injectors and set up throttle bodies. It started and ran fine, we then balanced the throttle bodies and was running as smooth as a button. It then misfired and stopped, would not restart, this time it had an intermittent spark.
We took the pickups off his own bike and fitted them. We had tested the pickups at the start and ruled them out because they tested fine
With the different pickups in the bike started and ran like a dream, he got a new set of pickups, replaced them and bike has been d
running perfectly since.

Long story, but might be no harm in checking the connection on the pickup and the condition of the stator and ensure the pick is bolted on to the stator cover properly


Trinafzs

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Re: fzs 600 carburettors
« Reply #37 on: 05 August 2022, 02:36:38 pm »
Did you ever resolve the fault? I’m reliving the same issue after removing the carbs and now I have a lumpy sounding engine when it does run and it cuts out. Now looking at getting the carbs cleaned using ultrasonic. Any thoughts?