Pops and backfires

My '00 SV650S has started popping and backfiring.

I have read some other threads here along similar lines, but these all refer
to something having changed to lead to the noises, with mine nothing has
changed...
As I'm a bit of a numpty I don't really know what info to supply, so I'll
tell you what I can...

It's a UK model SVS (2000) with 32,000 on the clock (FSH), no
engine/fuelling mods, just a Scorpion can that's been on every day (except
MOT days) for 3 years.
The popping started a few days ago and only occurs (intermittently at that)
when having closed the throttle completely for braking, it usually happens
in the 3 to 4.5k rev range and varies from a farty 'pop' to a shotgun bang.
If I pull the clutch lever in it doesn't happen, only when braking on the
engine (and/or with brakes).
I can rev the nuts off it in neutral and it settles back down to idling with
no abnormal noises...

Checked exhaust for unexpected holes and didn't find anything. Except the
one at the end!

Covered end of can with my foot and didn't hear anything that resembles air
leaking from somewhere else, it would be easier on a nice cold morning as
this will enable something visible, I may be missing the noise due to not
really knowing what to listen for.

I have dumped a small bottle of 'Redex' into the tank to clean out the
carbs, I'll see if that changes anything.
There certainly aren't any running problems I've noticed, no loss of power,
no loss of acceleration, idles smoothly and no changes to fuel consumption.

Does the problem I've described sound like something to worry about?

 

Check again - this is almost certainly the area causing the problem.
try checking the securing bolts and any joints too, as these are
perhaps the more likely areas.

 

It was somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Matt \(IS Team\)"

Small pops and bangs getting louder as time goes on are commonly caused
by slight leaks at the point where the headers meet the cyl head. You'll
probably get away with tightening the header nuts / bolts up for now,
but you'll find it returns in a while. The only proper cure is to
replace the exhaust header gaskets and use a little bit of exhaust
gasket sealer on them..

--

Dave

GS 850 x2 / SE 6a
SbS#6 DIAABTCOD#16 APOSTLE#6 FUB#3
FUB KotL OSOS#12? UKRMMA#19 COSOC#10

 

Grimly Curmudgeon wrote

An overly lean mixture is sometimes blamed for this as well but although
having experience of it on my Old lean burn califnian spec VT I have
absolutely no clue as to why this should be the case.

 

<snip>

What colour are your plugs?
My GSX1100F had some pretty good backfires when it started to foul the
plugs. All it needed was an oil change (old oil was like piss).


--
Andy Haworth, MIB#15
Suz GSX1100F
Suz GS550 Katana '82
Suz GS550 Katana '84
MZ ETZ125