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K100-forum.com » Technical, repair and troubleshooting » Engine and transmission » Compression test

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

tezk100rs

tezk100rs
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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 Wed May 15, 2019 7:09 am

92KK 84WW Olaf

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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 of curiosity had you the fairing lower on or off?


__________________________________________________
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 49,200 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
    

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

tezk100rs

tezk100rs
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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 Wed May 15, 2019 8:48 am

Point-Seven-five

Point-Seven-five
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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: 1991 K100RS "Moby Brick Too"
 
Past:
1994 K75RT "Ilsa, She Wolf of the SS"
1988 K100RS SE "Special Ed"
1994 K75S "Cheetos"
1992 K100RS "Moby Brick" R.I.P.
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 Wed May 15, 2019 9:13 am

Rick G

Rick G
admin
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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


__________________________________________________
"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
    

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

92KK 84WW Olaf

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Life time member
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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 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 49,200 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
    

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