Back Firing

Fitzdangle

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My 1998 1100 sometimes back fires under deceleration,sounds like a gun going off and just the job to frighten the odd old lady or two,but more importantly is it doing any long term harm and what are the likely causes ? :beer: :beerjug:
 
'Back Firing' under throttle off is due to air being sucked into the exhaust system normally where the silencer joins the down pipes.... it's nothing to worry about and wont do any harm.... as you say keeps the granny’s on there toes.

If you really want to stop it just put some exhaust joining compound before joining the pipes together.
 
Nice one Paul, I think I`ll leave it as it is, It cost me over £200 on my last bike (VFR 800) to make a racket !
This back firing certainly adds character and it`s for ...FREE !:beer: :beerjug:
 
Paraniod who Me?

Paul G said:
'it's nothing to worry about and wont do any harm.... as you say keeps the granny’s on there toes.

Hummm not sure Paul I might worry if it was more than once in a blue moon, I recon it will wreck something eventually, after all its an explosion of some kind.

It could also be due to an inbalance of throttle bodies or an inlet air leak, and something is running very lean to cause it and that means hot, one of our clan had a serious pop and banging going on and it melted the left hand panier, are we talking std exhausts here or wot?

Get it checked out, Regards G....
 
Bog Standard

I`ve only had the beast a month,gave it a good run up to Motor Works on New Years Eve (220 miles)and it must of happened about three times.
The bike is standard but it is close to a 24,000 service.....hence the trip to Motor Works.....much more fun than mail order!:bounce1
 
Re: Paraniod who Me?

needlongerlegs said:
Hummm not sure Paul I might worry if it was more than once in a blue moon, I recon it will wreck something eventually, after all its an explosion of some kind.

Isn't that how 4 strokes work....

Suck....... intake
Squash.. compression
Power.....kin big bang
Exhaust.. noise

Any unburnt fuel in the exhaust will go bang when air is sucked back in on throttle off.

Mine has done it now for 25k+ and no problems
 
i'd say it is almost certainly a leak on the exhaust side & should be simple enough to fix.

i don't think it will do any harm (at least in the short term), but i wouldn't let any vehicle of mine do it for long.

i'd find it too embarrasing to have others think i'm driving an ill maintained bike.
 
Re: Re: Paraniod who Me?

Paul G said:


Isn't that how 4 strokes work....

Suck....... intake
Squash.. compression
Power.....kin big bang
Exhaust.. noise

Paul, RR certainly taught us both all the technical jargon didn't they. I remember it as

Suck
Squeeze
Bang
Blow

Tim
 
:hapybnce: :hapybnce:

Mr Reece, Mr Owen & Mr James aahh I'd forgotten about them until you said that..... there again it was 25 years ago :(
 
Does the bike have an Oxygen sensor?

All 1100 GS bikes in Australia didn't have the Oxygen sensor, nor did they have a Cat in the exhaust system.

My 1100 has backfired since new and most others I know of also do the same. The problem usually occurrs when the bike has the throttle shut off and the injectors then shut off the fuel.

As the revs descend down to just under 3,000 RPM the injectors fire up again, this is when the injectors give a little bit more fuel than needed because the Oxygen sensor isn't there to tell the computer exactly when to shut off the fuel supply to the injectors. It is at this point that the backfire occurs!

A friend of mine has recently had an oxygen sensor fitted to his 96 1100GS I'm watching this closely as it appears that the backfire has all but been eliminated as a result of this modification.

At least that is how I understand the back fireing problem of all 1100 GS bikes.

Mick.
 
Fitzdangle

I've been messing with my air mixture screws; since the last twiddling session my bike has been backfiring when I close the throttle. It sounds like your mixture screws just needs adjusting slightly.

:beerjug:
 
Service Time

Thanx for that Rob,I`m about to do a major service so balancing the throttle bodies should sort it then !:bomb
 


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