+- Fazer Owners Club - Unofficial (https://foc-u.co.uk/mybb)
+-- Forum: Bikes, Hints'n'Tips (https://foc-u.co.uk/mybb/forumdisplay.php?fid=66)
+--- Forum: FZS600 Fazer (https://foc-u.co.uk/mybb/forumdisplay.php?fid=78)
+--- Thread: FZS 600 '99 Issues, ideas? (/showthread.php?tid=83849)
FZS 600 '99 Issues, ideas? - NJD - 08-09-25
Hi,
FZS 600 '99 at 49k miles with multiple symptoms and i'm looking for ideas on causes.
- when cold starting on full choke the bike will cut out sometimes, however starting is not overly difficult for now (mostly two attempts).
- when cold starting ive noticed a slight metalic sound from engine when throttle is opened, seems fine and not noisy upon idle however the bike doesn't sound 100% roaring to go when its cold.
- increased fuel consumption (but this has been over a long period), i'm getting 104-115 miles before the bikes indicator is showing in the bottom section (i apprechiate its hard to gauge as it depends how much i fill up, never tracked mpg)
- slight loss of power, stronger power surges in a certain rev range; however still reaches 60-70mph.
Bike runs on all four cylinders (tested by spraying water at hot exhuast downpipes). Oil, plugs and filter (k&n re-use) serviced within the last 6 months.
I visited local bike shop and he suggested buy an offical yamaha air filter, as i thought it could be valves but he said it wouldnt be. To me it sounds internal at top end.
Not sure there's anything fatal, but perhaps early signs of something or something that's causing me to notice slight issues.
RE: FZS 600 '99 Issues, ideas? - BBROWN1664 - 08-09-25
(08-09-25, 02:02 PM)NJD Wrote: - when cold starting on full choke the bike will cut out sometimes, however starting is not overly difficult for now (mostly two attempts).Most FZS600's barely need half choke, especially in the summer as they run slightly rich usually
(08-09-25, 02:02 PM)NJD Wrote: - when cold starting ive noticed a slight metalic sound from engine when throttle is opened, seems fine and not noisy upon idle however the bike doesn't sound 100% roaring to go when its cold.Difficult to say without hearing the issue - maybe post a video on here - but it could be a bit of chain rattle or it could just be the bike saying, take it easy for a few mins while i warm up a bit
(08-09-25, 02:02 PM)NJD Wrote: - increased fuel consumption (but this has been over a long period), i'm getting 104-115 miles before the bikes indicator is showing in the bottom section (i appreciate its hard to gauge as it depends how much i fill up, never tracked mpg)104-115 miles could be anything - how many litres do you add when it gets to this point? Shoul dbe about 10 which means you are barely using 2/3 or the tank. These bikes typically do about 160 before the light comes on (ignore the gauge)
(08-09-25, 02:02 PM)NJD Wrote: - slight loss of power, stronger power surges in a certain rev range; however still reaches 60-70mph.Now we are getting there - You have said its been serviced fairly recently but when were the carbs last balanced and TPS reset? Have you checked the valve clearances?
RE: FZS 600 '99 Issues, ideas? - NJD - 09-09-25
Carbs have not been balanced in my ownership, and at a rough guess thats at least 3-5 years. I did pop into my local bike shop and explained 'slight loss of power, power surges, increased fuel, slight metal sound at cold and hard start' but they simply said to replace the k&n filter with an OEM one and that it would not be the valves because they get tighter as they wear or come out of adjustment. I rode away with an eye roll hence why I came here. Seems like a needle in a haystack to get shops to do anything these days, I recall phoning before I think to do with some wiring and the place told me to do it myself. Right, thanks.
'(ignore the gauge)'
I may just have to, I think the problem I have is that my commute is out the way with limited petrol stations beyond a point so generally have to fill up way before to cover myself. I'll start tracking my MPG via the fuelly webiste (if it still exists) to keep an eye on what I'm getting because as you point out it could mean anything.
At 49k miles its a bit of a triggers broom, i'll have a poke around at a few things the weekend and work my way up.
RE: FZS 600 '99 Issues, ideas? - Gnasher - 09-09-25
Power surging is a symptom of lean fuel mixture often caused by partially or blocked jet, vacuum leaks, sticking fuel metering valve/s sticking float/s.
All or a mixture of above will give you power surges and increased fuel consumption. Firstly check for vacuum leaks around the carb intake rubbers, if nothing is found. Strip, clean and check all component for wear/damage.
RE: FZS 600 '99 Issues, ideas? - NJD - 11-09-25
I'll take a look at the fuel system too, thanks for the help.
RE: FZS 600 '99 Issues, ideas? - Faze2 - 01-10-25
(11-09-25, 01:44 PM)NJD Wrote: I'll take a look at the fuel system too, thanks for the help.Have you tried running some fuel system cleaner through it?
RE: FZS 600 '99 Issues, ideas? - NJD - 28-10-25
(01-10-25, 08:54 PM)Faze2 Wrote:(11-09-25, 01:44 PM)NJD Wrote: I'll take a look at the fuel system too, thanks for the help.Have you tried running some fuel system cleaner through it?
Hi,
I finally found the cause as a loose exhuast bracket (got worse over time). I replaced the system a while ago with a delkevic system however it seems the nuts I used to secure the bracket to the engine were not the most anti-rust they could have been and have not errored.
In the picture below its the nut at the 'top' of the picture (second on the inside furthest away). I cannot undo it however because it is no longer the shape of a hex nut, and the space is ultra tight.
I have tightened the one on the other side a little, but of course it needs to be uniform not overtightened so does move a litte still.
Is there a way to esentially cut the nut from the thread, maybe a small file or saw blade? or is best to let it rot away over winter and replace when it eventually falls apart.
The bike runs and starts fine, maybe it feels a little underpower at low speeds or not as punch but nowhere near what it was before i found it over the past week and tightened the other side.
ALL the nuts need replacing, any suggestions on what grade / type would work bet to avoid the errorsion?
https://i.postimg.cc/XvnVF7Lv/IMG-6716.jpg
RE: FZS 600 '99 Issues, ideas? - Schomosport - 28-10-25
(09-09-25, 02:57 AM)NJD Wrote: I may just have to, I think the problem I have is that my commute is out the way with limited petrol stations beyond a point so generally have to fill up way before to cover myself. I'll start tracking my MPG via the fuelly webiste (if it still exists) to keep an eye on what I'm getting because as you point out it could mean anything.
Photo of the mileometer when you stop for fuel, always fill to the same point e.g. bottom of tank neck, keep the receipt. Work out the fuel consumption.
(Last fuels stop miles - previous fuel stop miles) then divide by litres you added equals miles per litre, multiply by 4.55 equals miles per gallon.
RE: FZS 600 '99 Issues, ideas? - Grahamm - 28-10-25
(28-10-25, 08:03 PM)NJD Wrote: In the picture below its the nut at the 'top' of the picture (second on the inside furthest away). I cannot undo it however because it is no longer the shape of a hex nut, and the space is ultra tight.
If that's a coolant hose on the left, you can drain the system (when was it last refreshed?) and get that out of the way, then invest in a set of damaged/ rounded nut removal tools like these:
https://www.sealantsandtoolsdirect.co.uk/damaged-rounded-bolt-nut-remover-10pc-socket-set-467893
You'll probably need to use a wire brush/ Dremel to get the rust off it first, then soak it in PlusGas or similar penetrating oil and maybe get a blowtorch on it to help shift it without breaking the exhaust stud.
RE: FZS 600 '99 Issues, ideas? - unfazed - 28-10-25
The K&N filter works fine with the 600 as they run a little rich from day one usually just needs to be cleaned and re-oiled.
Was the fuel filter ever changed?
Clean and re-oil the K&N and change the fuel filter first. Easiest things to do before taking things apart.
RE: FZS 600 '99 Issues, ideas? - NJD - 29-10-25
Thanks for the further responses.
I'll look into the nut remover tool as i can get a shallow socket in place but of course because its errorded it doesn't fit.
For now I don't think its anything else that's been mentioned, but will look into if it continues after i get chance to replace the nuts.