Gonna post my issue on here for the wider audience to see if anyone can pinpoint or recognise my bikes problem.Last couple of weeks my 600 has been suffering from a very mild "shivering" effect at lower revs, and i'm not entirely sure what to do about it or what's causing it?It's nothing major, yet, but it is there, which means it's bugging the hell out of me.And it's not a stutter, or a hiccup like you would get with an air leak, but similar to the noise a person would make when they are very cold and shivering, but as stated it's only a mild effect.Otherwise the bike is mechanically sound and looked after.Tickover is rock solid, needle doesn't move from 1200rpm, no hunting or anything.Approaching 49,000 miles, mainly used for commuting.Recent brand new TPS, in correct position at 5000rpm.New battery a few months ago, and bike starts first time on the button, no choke needed at all.K&N air filter cleaned and re-oiled a few weeks ago.Oil changed within last couple of months, and cooling system is all fine and air tight.NGK spark plug caps.Carbs balanced by me 3 days ago, all totally level, which helped a lot but not got totally rid of it.Quill aftermarket end can, been on there for years though, so totally ruled out.Mainly happens under 3000rpm, if i pull the throttle back it runs perfectly, no coughing spluttering or anything, absolutely fine with smooth and efficient delivery of power.Not changed plugs for a while, but i don't do high mileage at all, so although i don't actually think they need replacing i never jotted down when i last changed them, so i've ordered some new NGK Iridium plugs anyway to rule them out just in case. So, anyone got any ideas at all, 'cos i'm a little bit stumped to be honest?
All I can think of is that it's perhaps due to backlash in the drivetrain: cumulative slop due to clutch, gearbox chain and cush drive.Does it clear if you drag the back brake slightly?
changed garages lately? or make of fuel?have you drained the bowls?
Have you checked the chain to ensure correct tension, lube and that none of the links are siezed or stiff??
Restricting fuel flow would affect high speed performance long before it would be noticeable at low revs.I'll go with Toady's theory, my FZS600 is less happy when fed higher octane petrol.
Fuel filters only a fiver. What do you mean shivers?Like sometimes when you accelerate on the motorway and it feels like you've found a dead spot in the rev range?Or does your bike physically shiver? In which case does it also make a noise like "brrrrrrrr".