BMW K bikes (Bricks)

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1Back to top Go down   Compression test Empty Compression test on Wed May 15, 2019 7:03 am

tezk100rs

tezk100rs
active member
active member
Hi all what is a good compression test value for late eighties k100lt im measuring 120 120 120 100 cyl 1 to 4. What is maximum pressure viz when bike is new and minimum pressure for the bike to start and run.Would like to hear from people who have done the test their resullts and how the bike performs ...regards tez

    

2Back to top Go down   Compression test Empty Re: Compression test on Wed May 15, 2019 7:09 am

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
One of the most common issues on them is how the test was done.

I haven't bothered doing one on any of mine but there are threads on it here. Your 1-3 are very consistent but a little over 8:1 and no 4 slightly down slightly under 7:1. Our ofcuriosity had you the fairing lower on or off?


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

3Back to top Go down   Compression test Empty compression test on Wed May 15, 2019 7:28 am

tezk100rs

tezk100rs
active member
active member
Test done on motor that had been sitting for a long time ..engine is new to me so I dont know anything about it ..test done with all spark plugs removed and each cylinder tested one at a time with crappy hand held compression tester. Throttle bodies were closed at time of test. I did notice that the numbers got higher after repeating the test a few times so im assuming the oil is getting up to the pistons

    

4Back to top Go down   Compression test Empty Re: Compression test on Wed May 15, 2019 8:48 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Throttle wide open. Crank until pressure stops rising. Usually around three to four compression strokes.

I have gotten between 150 and 180 psi. It's the uniformity of the readings that you're looking for. A shot of oil in the cylinder will bring the reading up if the engine has not been run in a while.


__________________________________________________
Present:
1994 K75RT
1991 K100RS

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

5Back to top Go down   Compression test Empty Re: Compression test on Wed May 15, 2019 9:13 am

RicK G

RicK G
VIP
VIP
@Point-Seven-five wrote:Throttle wide open. Crank until pressure stops rising. Usually around three to four compression strokes.

I have gotten between 150 and 180 psi. It's the uniformity of the readings that you're looking for. A shot of oil in the cylinder will bring the reading up if the engine has not been run in a while.
Yeah what .75 said


__________________________________________________
"Every normal man must be tempted, at times, to spit upon his hands, hoist the black flag, and begin slitting throats." from Mencken's 1919 Prejudices

Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

6Back to top Go down   Compression test Empty Re: Compression test on Wed May 15, 2019 3:33 pm

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
N0 4 is tricky to do with fairing lower on.

1-3 are consistent but low.

Follow .75 and Rick G and hopefully you will get better readings.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now91,850 miles
1983 K100RS 0011175 Fricka 29,495 miles Damn K Pox
    

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