Date: 29-05-24  Time: 12:03 pm

Author Topic: 1999 FZS 600 - Low RPM bog down, ideas?  (Read 909 times)

NJD

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1999 FZS 600 - Low RPM bog down, ideas?
« on: 29 February 2024, 05:12:42 pm »
I use my FZS 600 '99 for commuting daily and recently it developed a problem with a noise coming from the right hand side of the engine. I only notice this sound when the bike is started from cold, and the sound reminds me of a tractor: clattering like. It doesn't happen all the time, and is faint. Comes and goes. Not constant.


I first noticed it/it started happening after I washed the bike with a hose pipe and then used the Bruhl dryer straight after and then started the bike to remove any remaining droplets of water. The engine temp light came on, and the bike sounded rough. The first few rides after that were very bumpy, and the bike ran rough for the first mile or so (juddering, low on power, surging and then perfectly fine after about 3k). I drained some fuel out of the float bowel and it was clear and smelt of petrol, thinking I'd gotten water in the carbs or suchlike. I've not done anything other in that side of things.


A week later the bike starts fine and starts first time, I've changed the spark plugs and that helped but the noise is still there and the bike is still low on power from cold occasionally (not every single time) sounds like it wants to die and sometimes tries to but doesn't and keeps running. Its nowhere near as bad. Seems like an intermittent issue. When it plays up it goes through a phase and then suddenly everything is fine power wise and it runs normal. Always below 3k and in first (not noticed an issue in other gears). Runs fine, reaches 70 mph etc perfectly fine. Goes to the rev limiter. No stutter on throttle input.


Before I ask the shop to take a look what can I do. HT leads, coil pack, air filter?

BBROWN1664

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Re: 1999 FZS 600 - Low RPM bog down, ideas?
« Reply #1 on: 29 February 2024, 09:49:00 pm »
could be a bad plug lead, water in the cap etc.
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darrsi

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Re: 1999 FZS 600 - Low RPM bog down, ideas?
« Reply #2 on: 02 March 2024, 08:06:22 am »
Make sure the bike is set to around 1250rpm once it's warm, it might be a bit low, especially in cold weather.
I'd check the TPS as well, as your symptoms are similar to a faulty one, or one that's possibly in the early stages of going bad. Only takes a minute and worth ruling out.
If you use a hose again to clean soap off the bikes engine it's worth warming the bike up and leaving it ticking over as you're doing so to avoid water getting into unwanted areas.
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Gnasher

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Re: 1999 FZS 600 - Low RPM bog down, ideas?
« Reply #3 on: 02 March 2024, 12:26:58 pm »
I use my FZS 600 '99 for commuting daily and recently it developed a problem with a noise coming from the right hand side of the engine. I only notice this sound when the bike is started from cold, and the sound reminds me of a tractor: clattering like. It doesn't happen all the time, and is faint. Comes and goes. Not constant.

The noise is suggesting not firing on all cylinders

I first noticed it/it started happening after I washed the bike with a hose pipe and then used the Bruhl dryer straight after and then started the bike to remove any remaining droplets of water. The engine temp light came on, and the bike sounded rough. The first few rides after that were very bumpy, and the bike ran rough for the first mile or so (juddering, low on power, surging and then perfectly fine after about 3k). I drained some fuel out of the float bowel and it was clear and smelt of petrol, thinking I'd gotten water in the carbs or suchlike. I've not done anything other in that side of things.

A week later the bike starts fine and starts first time, I've changed the spark plugs and that helped but the noise is still there and the bike is still low on power from cold occasionally (not every single time) sounds like it wants to die and sometimes tries to but doesn't and keeps running. Its nowhere near as bad. Seems like an intermittent issue. When it plays up it goes through a phase and then suddenly everything is fine power wise and it runs normal. Always below 3k and in first (not noticed an issue in other gears). Runs fine, reaches 70 mph etc perfectly fine. Goes to the rev limiter. No stutter on throttle input.

Before I ask the shop to take a look what can I do. HT leads, coil pack, air filter?

I see a lot of this sort of thing at this time of year i.e. odd and intermittent electrical issues, such as warning lights coming on etc.  It's nearly always down to water ingress into electrical fittings and connectors.  Take apart every connector block, check for corrosion, clean and use some dielectric grease.  The fact the bike is running fine above 3k, is strongly suggesting you've got a pilot circuit issue on one or more of the carbs.  Forget coils, TPS, plugs and air filter etc if it was any of those the bike wouldn't run above 3k or very badly and you'd have starting issues which you've not got.

The odd noise you've heard/got is more than likely slightly out of balance carbs. 
Later

NJD

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Re: 1999 FZS 600 - Low RPM bog down, ideas?
« Reply #4 on: 03 March 2024, 05:41:28 pm »
Thanks for all the suggestions. I managed to find an old new spark plug cap and crimped the HT write on the problem cylinder and fitted it, sounds a little louder. Obviously will need more testing.


Probably going to order new coils and keep them stored away since I found an old thread on a different forum of me having the same issue on the same side from two years ago, and then again a year later and crimping the wire with new HT leads is all I ever did on that front. Well besides replace the starter relay at some point.


Will definitely be lubricating connectors across the bike when I get the chance, happened recently with my rear brake light too (sticking on due to invisible corrosion, and solved with some jelly) so could easily be effecting something else.


Carbs are probably on the cards at some point, but since it gets regular use and I've had it a few years I'll try and save the pennies unless the problem carries on and it needs doing (shop job to me).


Will update anything else goes wrong or I try things and don't work. Cheers.