BMW K bikes (Bricks)


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1Back to top Go down   fuel leaking out of air box plenum  Empty fuel leaking out of air box plenum Mon Jun 19, 2023 3:08 pm

Chris

Chris
New member
New member
My father was notorious for improving - getting more speed- out of his Motorcycles.  He passed his 1985 K100RS on to me.  At the time he de-tuned it to slow it down. I rode it a total of ten times before parking it - The problem was as i was on the way home from work i saw a puff of smoke - behind the wind screen. I leaned the bike over just in time to see a drop of fuel come out of the coupling to the air box and hit the hot engine igniting - I decided not to be that flame on the road-  Seven children and 16 years later i am cleaning her up. has any one had this problem?  No, it did not come from the tank i checked it first.

    

Dai

Dai
Life time member
Life time member
Check the timing (the position of the HES). If it's too far advanced it might spit fuel backwards, but what you say also suggests you are going to need to replace the z-tube, all three vacuum covers (cyls 1- 3), the vacuum tube (cyl 4), inlet rubbers and manifold rubbers.


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1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

92KK 84WW Olaf

avatar
Life time member
Life time member
Dai wrote:Check the timing (the position of the HES). If it's too far advanced it might spit fuel backwards, but what you say also suggests you are going to need to replace the z-tube, all three vacuum covers (cyls 1- 3), the vacuum tube (cyl 4), inlet rubbers and manifold rubbers.

If it is 85 you may have a vacuum sensor, another vacuum tube goes from No 1 around the front of the airbox, the sensor is mounted beside the fuel pressure regulator. Replace it with a cap [vacuum cover] same as 1-3.

But I am a devil and going to say replace the fuel lines because it could have been coming from a cracked line as they are all under pressure and bouncing off the air box.

Does the bike have the CA tank venting system? ........ I am not familiar with it but I have an idea the gas tank vents into the air box....possible the pipe inside the tank is set damage and too low and its acting as an 'overflow'


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1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 58,200 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 51,800 miles.
1983 K100RS 0004449 Odette R100 colours 58,000 miles. Sprint fairing now 63,390 miles

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

Rick G

Rick G
admin
admin
Moved to a more relevant section
Rick G


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"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1999 K1100 LT with a Big Block 1200
    

Laitch

Laitch
Life time member
Life time member
A puff of smoke? A drop of coolant, grease or oil will smoke if heated enough. A drop of gasoline evaporates; gasoline vapors flash and flame when ignited, not smoke. Always taste whatever leaks to make a positive identification. Laughing If it tastes like chicken, check for broth leaks.


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1995 K75 90,000 miles
    

Suzi Q

Suzi Q
Life time member
Life time member
"If it tastes like chicken, check for broth leaks."

Has it been sunny? You need to be wearing your hat.


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Sometimes I'm not really Suzi Quatro.
    

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