So, there's this noise...? Experience wanted!

[Bleh]

Right, the noise....
It's almost hard to explain but I'll try my best. The best description I can think of is it's like a frictional noise but not a rattle by any means.

I first noticed it just over a month ago and has become a more frequent occurrence. It never happens when sitting there idling in the morning warming up before use or at any time when idling, can give it some good revs and still doesn't happen. It only happens when coming to a stop say at a set of lights or a junction for example. I've experimented with considerations such as ill surfaced discs/ pads by visual inspection and refraining to use the front when approaching a junction (get no pulsing to lever either, nice and sharp!) and vise versa with the rear so I know it's not the brakes in any way, bearings front and back solid, head stock solid (but planning a new year service anyway!).

I'm confident it's engine area related and to expand on conditions, it only appears to happen when the revs are decreasing after being under load (and almost at coming to a stop), doesn't matter if I'm in second, first, neutral either. My initial assumption was it may be coming from the cards as I know they need doing badly, I just genuinely haven't had the time yet but it's a priority in my 'next five minutes I get' list...

There doesn't seem to be a loss of power, opens up with a grin, engine breaking is nice when coming to a decent speed corner and any other time for that matter. And I say it again, it doesn't happen if giving it some nice revs in neutral, only appears to happen when nearing a stop!

Further info that may be relevant: She's sometimes grumpy starting in the morning (confident this is carbs though, they do need an urgent overhaul). Oil level is good but I do have some Motul 5100 ready to change old for new and a nice new filter (for when I do the cards ). Have had a few occasions when I've felt air being blown back through the air box (this probably the more eye rising one).

When I first felt/ heard this I went and bought some new plugs and air filter to give it a 'micro-service' and upon changing, old plugs looked decent (as far as old plugs go...) but the filter was a bit filthy so she was pleased to have a new one.
Wiped out the little oil residue inside the box (as per norm) and made sure to get every last smudge so to inspect upon doing the carbs (them bloody carbs!!!), so to suggest potential PR problems or valve problems although I'm a little paranoid about these, I'm not overly concerned because the has good power, never back fires etc etc

I'm hoping it's a case of the worst carbs I have ever come across and maybe the slide is rubbing against some filth etc... I'm praying to the 'God of Bike' it's not a dodgy valve/ seal/ spring, piston rings or worse.

Any input and experience would be massively appreciated,

Thanks in advance.

[popkat]

The blow back in the airbox sound like the firestorm "carb fart", not that uncommon and not really a problem, call it character, everyone i've owned or ridden has done it.

Has it always had the noise, did you just notice it or was it something new ?. It could be cam chain tensioner spring broke but they've had a stopper mod done.
I recently fitted manual cam chain tensioners to a strom, it had a chatter type sound from the front cylinder, could only hear it when fully warmed up after a ride, the tensioners I took off rattle a little if you shake them, the noise could well have been a failed tensioner but with stopper mod, also this bike was one tooth out on the cam timing so this may have caused the noise too. I'm yet to find out if the noise as gone away as the owner hasn't bought it back, I will ring him in a couple of weeks and find out if it's all good.

[Wicky]

Check your chain adjustment isn't getting loose and just touching on the exhaust when your weight is on the bike.

[lloydie]

sounds like its a carb fart , normally happens around 3000rpm and yes mine did it to

[darkember]

Dont worry yourself over rings & valves as these will affect performance & oil useage

[Bleh]

Thanks all, most seem to be mentioning a 'carb fart' (nice term btw ) which is what I strongly suspect.

There was/ is absolutely no rattle and I suppose the only way I can explain the type of noise is like a squeaky brake disc (but not as high pitched). I have suspected a stopper mod as the casing cover (which may as well be made of butter) is mashed up so indicates someone in the past has attempted some form of work and CCT's are in the pipeline but when the cash is there. Did have a message off Bazza to which I replied but am yet to receive a response back.

I'm also considering the possibility that someone may have jetted the carbs in the past and had difficulty setting them up but can't be sure until I get the buggers off and stripped down!