BMW K bikes (Bricks)


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1Back to top Go down   Air screw balancing Empty Air screw balancing Sat May 19, 2018 8:58 am

nobbylon

nobbylon
Silver member
Silver member
A question to those that know please. 
Trying to balance my K100 with carbtune and numbers 1,2 and 4 cylinders are requiring 1.24-1.5 turns out but the closest I can get no.3 is when the screw is 2.5 turns out and turning out beyond this has no further effect. Does this mean that I possibly have an air leak between throttle body and intake stub on no.3? 
Bike new to me so can’t say if the body sync screws have been altered. There certainly isn’t any paint on them. Bike runs fine, no popping etc, idles at 1000-1100. Should I just leave it as is?
thanks j


__________________________________________________
R1100GS Feb 1995
K100RS July 1989
R90s June 1975
R75/6 Feb 1976
F650GD May 2001
    

2Back to top Go down   Air screw balancing Empty Re: Air screw balancing Sat May 19, 2018 9:41 am

Dai

Dai
Life time member
Life time member
Yup - sounds just like what happened to me and I had an air leak in the inlet rubber (the one on top). I replaced the lot - inlet rubbers and inlet manifolds (the ones on the bottom). IIRC it cost me £60 or thereabouts from Motorworks. After I'd changed mine the idle dropped from1100rpm to 800rpm with no other changes, so I then wound it back up to the recommended 960rpm -ish.


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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
    

3Back to top Go down   Air screw balancing Empty Re: Air screw balancing Sat May 19, 2018 10:20 am

nobbylon

nobbylon
Silver member
Silver member
Would the top rubbers have any effect? The rubbers between the throttle bodies and block sure. Ridiculously expensive for a piece of rubber. £34 for these and a fiver for the top ones.


__________________________________________________
R1100GS Feb 1995
K100RS July 1989
R90s June 1975
R75/6 Feb 1976
F650GD May 2001
    

4Back to top Go down   Air screw balancing Empty Re: Air screw balancing Sat May 19, 2018 10:50 am

duck

duck
Life time member
Life time member
It's probably the bottom ones.  You can confirm by spraying some starter fluid or other flammable substance around them.  If the idle increases then that tells you that there's a leak.  Or you can spray some water mist around them and see if the idle decreases.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

5Back to top Go down   Air screw balancing Empty Synchronization throttle bodies Sat May 19, 2018 11:24 am

caveman

caveman
Life time member
Life time member
Did you check valve clearance first?

    

6Back to top Go down   Air screw balancing Empty Re: Air screw balancing Sat May 19, 2018 12:23 pm

nobbylon

nobbylon
Silver member
Silver member
valve clearances, new timing chain and guides done a couple of weeks back. The bike runs superbly but I like to mess. I’m suspecting the weird buzzy sound or nigh frequency rattle from 2500-3000 rpm is either the alternator drive bearing inside the rear casing or more likely a couple of worn rivets on the output shaft with a worn backlash circlip.
Will keep riding and see what happens. 
I’m busy replacing the fork stanchions on my 75/6 so it will have to wait!


__________________________________________________
R1100GS Feb 1995
K100RS July 1989
R90s June 1975
R75/6 Feb 1976
F650GD May 2001
    

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