k100rs backfire

fizzer · Jan 16, 2013

hi guys,any ideas would be helpfull,i got an old 1990 k100rs ,normal riding fine,but after a a fair speed on the motorway when decelleration when coming off at a slip road it backfires,other than than it rides fine
cheers guys
ian

Ogmios · Jan 16, 2013

check your joints :spl1f:

no

- in the exhaust.
air leaks are one of the causes.
Good Luck.

DrFarkoff · Jan 16, 2013

They are getting old now

Probably just air getting in

What condition is the silencer in?

Linda's had that problem with Og for years now, I mean Og's backfiring! she's convinced there's air getting in somewhere! The rest of us are convinced about this air getting in too!

Ogmios · Jan 16, 2013

fizzer · Jan 16, 2013

exhaust is in good fettle,no leaks even where it bolts to the head ,i have took the plastics off and sprayed wd40 around the rubbers to see if its sucking air there ,and there is no rise in the revs ,so i am thinking maybe it may need the throttle boddies balancing up.

DrFarkoff · Jan 16, 2013

Eeeeeeeeeeeeeek

the dreaded WD40

I use 3 in one or ATF cos it doesn't "attack" the rubber

What about around the injectors ? Did you do there ?

seahorse · Jan 16, 2013

if its an 8v then probably the throttle switch needs resetting.

Harry Nicholson · Jan 16, 2013

I had a similar problem with my 16v . Adjusted the throttle position sensor , problem resolved .
Cheers

Harry

fizzer · Jan 16, 2013

seahorse said:
if its an 8v then probably the throttle switch needs resetting.

and how do you do that please :beerjug:

fizzer · Jan 16, 2013

:

fizzer said:
and how do you do that please

oh and yes i sprayed around the injectors ,no change in engine tone. :thumb2

seahorse · Jan 16, 2013

fizzer said:
and how do you do that please

Being lazy and lifted this from another site;

The problem is almost certainly a mis-adjusted throttle cut-off switch - located on the rearmost end of the throttle plate shaft assembly - left side of engine, just ahead of the coils. This switch is supposed to close - with a faint click - just as the throttle closes completely. This signals the ECU to cut the fuel flow to the injectors if RPM is over 2000. If it is mis-adjusted so it doesn't close (and click), then the injectors keep pumping in fuel even on throttle off conditions. This will cause the backfire. The switch is adjustable by loosening two screws and slightly rotating the entire switch assembly. Set this correctly and most of the K bike backfiring will go away.

I will add that you will need a small stubby screwdriver to get to the screws, certainly the innermost one.

fizzer · Jan 16, 2013

well thankyou very much seahorse,thats very good off you,i will have a look at that this week.
thanks again

fizzer · Jan 20, 2013

seahorse,mate firstly its a 1990 16 valve,i did what you said with the throtle position sensor,it was set to the max in anti clock wise,so i slackened the screws as you said ,but as soon as i moved it in the clockwise way it started to climb to 3000rpm ,so i put it back where it was and it ticks over nice ,so in full no air leaks and the tps is where it should be ,but the bloody thing still back fires on deceleration,any ideas :beerjug:

cheers folks.

k100rs backfire

fizzer

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Ogmios

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DrFarkoff

Grumpy Ole Git!!!

Ogmios

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fizzer

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DrFarkoff

Grumpy Ole Git!!!

seahorse

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Harry Nicholson

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fizzer

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