BMW K bikes (Bricks)

You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


1Back to top Go down   Compression test  Empty Compression test Sat May 12, 2018 1:53 pm

dakelvinator

dakelvinator
Silver member
Silver member
HI Just wanted to see what people think? I just did a compression test on my 1990 k100lt the results on the cylinders were 
1- 8.9 bar
2- 8.5 bar
3- 8.5 bar
4- 9 bar 
(Engine hot throttle open full) 
The resin why i did the compression test was due to oil consumption I know these engines use oil ect
but I worked out 0.4 of a litre on a 200 mile journey mostly motorway last weekend. 
Then i use it for commuting one day i spent a lot of time in traffic so 
it was running hot for most of the 30 miles or so and it used 0.3 of a litre (but it was a hard drive for any vehicle!). The only other thing to consider is it needs 
the flywheel oil seal doing but this only puts the odd drop of oil on the floor! same with the water/oil pump a rare drop on the floor! (no overheating ect) other wise the bike runs really well. Has anyone else had this sort of oil consumption? 
Love to know what the general consensus is? or do i have an other problem? i.e valve seals? thanks in advance K.

    

2Back to top Go down   Compression test  Empty Re: Compression test Sat May 12, 2018 8:18 pm

RicK G

RicK G
admin
admin
I would plan to fix the front and rear seals and see how it goes after that. I have seen the 16V engines use a lot of oil including my K1100, it was consistent loss until about 18 months ago when it suddenly started using a lot more so its been retired. Others I have seen go for a long time.
8V usually don't use a lot so just keep an eye on it. The smoke on start up can be bad sometimes but it doesn't seem to use much oil.


__________________________________________________
"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 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

3Back to top Go down   Compression test  Empty Re: Compression test Sun May 13, 2018 5:58 am

dakelvinator

dakelvinator
Silver member
Silver member
@RicK G wrote:I would plan to fix the front and rear seals and see how it goes after that. I have seen the 16V engines use a lot of oil including my K1100, it was consistent loss until about 18 months ago when it suddenly started using a lot more so its been retired. Others I have seen go for a long time.
8V usually don't use a lot so just keep an eye on it. The smoke on start up can be bad sometimes but it doesn't seem to use much oil.
Hi Thanks for your reply, I still plan on keeping it so i will be starting on the rear main seal soon enough but I will just keep an eye on it and not do anything too drastic! K.

    

4Back to top Go down   Compression test  Empty Re: Compression test Sun May 13, 2018 7:27 am

Dai

Dai
Life time member
Life time member
A compression test should always be done on a stone-cold engine. You're checking for leakage past the rings and the valve guides; when the engine is hot, these tolerances close up and give a false reading.


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

5Back to top Go down   Compression test  Empty Re: Compression test Sun May 13, 2018 7:58 am

Stumpy

Stumpy
Silver member
Silver member
If you frequently use the side stand, the oil can collect in the cylinder head. When the bike starts up oil gets past the value and into the cylinders, being burned off.

    

6Back to top Go down   Compression test  Empty Re: Compression test Sun May 13, 2018 9:10 am

duck

duck
Life time member
Life time member
Sometimes these bikes like to "hide" oil so if it seems to burn a lot on one trip it may be an anomaly so I wouldn't be as overly concerned as if it were consistently burning a lot of oil.  Even then, what are you going too do about it? Given the effort and expense required to do a teardown and rebuild it makes more sense just to swap in a used engine given the number of them available and relatively low cost.

And, from a pragmatic perspective, even if it does burn more oil than usual it's not something that is prohibitively expensive, it just means you need to keep a closer eye on the sight glass.

Then again, if it's really losing compression to the point of killing your mileage or noticeably degrading performance then it's time to part the bike or swap in a "new" motor.

JM02, YMMV.


__________________________________________________
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 (x2)
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
    

7Back to top Go down   Compression test  Empty Re: Compression test Sun May 13, 2018 10:20 am

RicK G

RicK G
admin
admin
Often an engine will be constantly using a small amount of oil but with short trips and round town running the oil loss is covered by a very small amount of fuel that gets past the rings, so it looks like it is not using any oil. Then comes a long run of a few hundred miles or so and the fuel evaporates and it looks like a heap of oil has been used so you top it up and it doesn't use any more.
I remember a car I had used almost a whole litre in the first part of a trip and not a drop more in the rest of the trip. It will be more likely to happen in cold whether when warm up takes longer and oil temperature isn't as high on the short runs around town.


__________________________________________________
"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 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

8Back to top Go down   Compression test  Empty Re: Compression test Sun May 13, 2018 11:17 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I have a 16V K100 that uses about the same amount of oil as yours(1.0L/900 miles).  Compression is good in all cylinders(~9.5 bar).  Engine has about 125K miles, runs smooth and strong, and starts readily.  Smokes when cold, but stops when warmed up.  I seldom park on the side stand, and oil consumption is consistant under all riding conditions.

I have replaced the valves stem seals, head gasket, rear main seal and the clutch o-ring with minimal improvement.  When I pulled the head for the valve stem seals I checked the cylinders and they showed no signs of wear. 

I suspect(hope, really) that I may have stuck oil control rings in the #1 and #3 cylinders.  I am now running Marvel Mystery Oil in the fuel and crankcase with the hope of loosening them up.  If it doesn't work, I will probably just keep on living with the consumption.  With the price of parts to do a ring job on the engine around $450 I can buy enough oil to ride another 50,000 miles.

I have looked at replacing with a used engine, but for the work involved installing a short block, I could just as easily install a set of low mileage pistons and rings for about $65.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

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
    

9Back to top Go down   Compression test  Empty Re: Compression test Sun May 13, 2018 11:31 am

duck

duck
Life time member
Life time member
The allowable oil consumption spec from BMW is 1.5l/1,000km. affraid


__________________________________________________
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 (x2)
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
    

10Back to top Go down   Compression test  Empty Thanks everybody Sun May 13, 2018 4:34 pm

dakelvinator

dakelvinator
Silver member
Silver member
Thank you all for your input, I think i will just be keeping a close eye on the sight glass from now on and not panicking!, I will probably go ahead and repair the rear main seal as it will need the splines lubing anyway as god knows when that was last done. It drives fine hardly smokes even on start up (unless on side stand), anyway if something drastic happens i am sure i will be back on hear looking for help! Thanks again K.  Very Happy

    

11Back to top Go down   Compression test  Empty Compression test Sat Feb 20, 2021 7:29 am

James P

James P
active member
active member
Hello all,
I’m looking at a 75k mile 1989 K100RS and the compression tests (cold, throttle closed) are all around the 9BAR mark. The engine running warm sounds sweet. The trouble is that COVID stops me going to see for real so these are videos. 
Any views? I thought it sounded ok. 
J

    

12Back to top Go down   Compression test  Empty Re: Compression test Sat Feb 20, 2021 8:17 am

RicK G

RicK G
admin
admin
Compression tests should be done with the throttle wide open and at least warm.


__________________________________________________
"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 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

13Back to top Go down   Compression test  Empty Re: Compression test Sat Feb 20, 2021 9:05 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Compression tests should be done with the plugs out as well. Ground the plug leads to prevent coil damage.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

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
    

14Back to top Go down   Compression test  Empty Re: Compression test Sat Feb 20, 2021 11:39 am

Suzi Q

Suzi Q
Life time member
Life time member
9 bar with a closed throttle sounds okay to me. But, as has been pointed out, comp testing is done with a wide open throttle, all the plugs out and a good battery - this gives you the highest possible reading. The difference between cold engine (cold cranking pressure - CCP) and a warm engine is minimal on a k. Main thing is that the readings are close across all cylinders.


__________________________________________________
Sometimes I'm not really Suzi Quatro.
    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum