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+--- 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
(Yesterday, 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
(Yesterday, 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
(Yesterday, 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)
(Yesterday, 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.