R1150 GS 2000 Backfires

[Benson]

Hey up

I am getting quite loud Back fires that I can more or less produce on command.

Travel at a constant speed say 60 MPH then throttle off and under engine braking will get not a popping but a full blown bang. I am still trying to work out if it also is causing a surge or if that is just me jumping. Seems to be worse if I ride a little bit more enthusiastically.

I had problems with surging and changed plugs and air filter which sorted that and the bike runs well a bit vibratey until i get in to 6th fuel seems to be ok getting 220 - 240 per tank.

Bike is still under warranty from BMW so should I just take it in or is this pretty normal?

 

[wildbeeste]

Backfiring like that is not normal.
Have you removed the Cat and an aftermarket exhaust can installed?
If so the fueling may need changing - Search for "cat code" I believe will produce the "steptoe mod". It is simple to do - one of the most complicated parts being getting the seat off.
If under warranty take it back and say "fix it" PLEASE.

 

[Greg Masters]

Yes, the usual cause is air leaks as a result of fitting Y-piece and/or aftermarket pipe.

Greg

 

[Colban]

As above.Do you have a std exhaust/cat or a Y piece/non-oem end can?.
Have you checked for airleaks/loose fittings in the system?.

 

[guzzimag]

Nothing to worry about. Mine occasionally goes off like a shotgun, so does my mates, so does other mate Dave's......etc etc

 

[cookie]

not that uncommon on bikes with Y piece and can.

mine would do it. no air leaks.

 

[D6]

mine did till i shoved a techlusion on it an disconnected the lambda,
it was just a bit weak, bmw,s crappy ign mapping, was desighned for the arc
now it never does it and the bike runs smoother,
i got mine cheap , depends what u wanna put up with really,
backfires used wisely can be a good source of fun (specially when theres pensioners about)

 

[Doctorbiker]

My 1150 with a Y piece backfires a bit - but it only does it when you close the throttle quickly. I find easing the throttle closed steadily results in a nice burbling and slight popping - like a real bike.

Shut the throttle quickly and a backfire can be produced.

Sean

 

[Hong Kong Nick]

My 2003 with Remus can and Y-piece has always backfired and it's not a problem. HOWEVER, today it started back firing like a machine gun and the bike was surging at very low RPM. THe idle speed seemed much lower than normal, too ...

The tank was moved the other day so that I could spray some of the cables under it (I was hoping that my non-functioning left indicator was simply caused by a wet connector or something ... alas no).

Cheers,

Nick

 

[cookie]

My 2003 with Remus can and Y-piece has always backfired and it's not a problem. HOWEVER, today it started back firing like a machine gun and the bike was surging at very low RPM. THe idle speed seemed much lower than normal, too ...

The tank was moved the other day so that I could spray some of the cables under it (I was hoping that my non-functioning left indicator was simply caused by a wet connector or something ... alas no).

Cheers,

Nick

check the throttle cables are seated properly at the throttle bodies

 

[Benson]

I have standard cat and silencer fitted and yes it only happens when you snap the throttle off. I have noticed that I have a carbon deposit splatter at the silencer /exhaust joint so I assume this is where I am getting the bang from. but if it is normalish ill live with it till I take it through for a service. Just took it for a 100 mile run and did not get one bang but I was feathering the throttle more today.

 

[MattW]

I have noticed that I have a carbon deposit splatter at the silencer /exhaust joint

There you are - if carbon is getting out, air is getting in.

On the overrun, the exhaust system pressure drops and it'll draw air in through a dodgy joint (especially when the throttle is snapped shut). All this nice cool oxygen then mixes with the unburned fuel mixture in the pipe and 'pop'.

If it's under warranty, get your dealer to remake the bad joint. If it's not, you can either live with it or do it yourself