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1Back to top Go down   Lost compression in back three cylinders Empty Lost compression in back three cylinders on Wed Jun 04, 2014 7:14 pm

enzo

enzo
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Went to pass a car today and the bike fell to one cylinder than died.  Fuel pressure is good so I pulled the plugs. Back plug fouled. Middle two wet with fuel. Replaced plugs but no go. Checked compression and have zero on the back three cylinders. Any ideas on what may have happened?


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

Comberjohn

Comberjohn
Life time member
Life time member
Head gasket?
Seems the most likely when three cylinders go at the same time.
Not to difficult or expensive to fix.


__________________________________________________
Life is not a rehearsal.
2010 VFR 1200F DCT 
2010 R1200GS(gone)
1986 K100 Silver(gone)
2012 K1600GT(gone)
1984 K100RT Madison Silver(gone)
1989 K100LT Stratus Grey(gone)
1984 K100 Red(gone)
http://www.johnsdrivingschool.co
    

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
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No compression on three cylinders all at same time? Sounds strange. Are you happy with the tester you used?

Loss of compression on two adjoining cylinders is often put down to head gasket failing between two adjoining cylinders. Not the end of the world. Could it happen between three? Not sure but the fact that its three and not all 4 seems to point this way. I wondered if the timing chain might have jumped but I think it would take out all 4.


__________________________________________________
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 now 98,780 miles
1983 K100RS 0011171 Fricka 29,495 miles Damn K Pox Its a Bat outta Hell No 32,600 miles
    

enzo

enzo
active member
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Pulled the valve cover and stared awhile. All looked good to me. Until I noticed the intake cam is broken in two just past the first cylinder. Maybe I got lucky. Lost compression in back three cylinders 20140604_162747


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

Snod Blatter

Snod Blatter
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Life time member
Lucky if it broke by itself, unlucky if it broke because something it presses on wouldn't move.. Any marks on the pistons if you can see inside through the plug holes? Maybe even try tapping the tops of the valves, see if one sounds more solid than the rest? Or maybe the other end of the cam seized? All of these are totally bizarre of course!


__________________________________________________
1989 K100RS SE ABS 8v  VIN: 0149214
Others: 1.5 x Honda CBX250RS-E, '94 CB250, '95 TRX850, '16 Z250SL
http://justbikethings.blogspot.co.uk/
    

92KK 84WW Olaf

92KK 84WW Olaf
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That happened in my [diesel] car a few years ago and did a lot of damage. I still have the car and it was only when I was doing some work under it that I noticed the sump had been off at some point. I asked the garage when I was next out there, as it was covered by warranty they had stripped and rebuilt the engine. I am curious as to why the camshaft broke in the first place but absence of compression suggests three bent intake valves meaning head off. If the timing hear and exhaust camshaft are all ok you need to check of the two broken camshaft pieces have dumped metal filings or swarf where the two faces were rubbing off each other.


__________________________________________________
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 now 98,780 miles
1983 K100RS 0011171 Fricka 29,495 miles Damn K Pox Its a Bat outta Hell No 32,600 miles
    

enzo

enzo
active member
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Cam actually was broke in to three pieces! Tops of pistons look okay. No signs of the camshaft seizing. Going to purchase a leak down tester to see if cylinders are holding pressure. 

I may have missed a gear and over revved. 

Lost compression in back three cylinders OvKlYHSuTDo-ygoXr8BZDi27ZtU4SGxUfLkmUs8g7f2V=s219-p-noLost compression in back three cylinders 20140604_172229


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

Avenger GT

Avenger GT
Life time member
Life time member
Very strange!! The inlet camshaft on my spares bike was broken in the middle of the bearing between cylinders 1 and 2, but the cause was very obviously a lack of oil. The cam lobes and shims were blue from heat, and the shaft had picked up on the bearings. I started it before I opened it and there was some racket out of the engine.

    

japuentes

japuentes
Life time member
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Hi, as I see it, maybe the camshaft was not properly settled, and being what seems to bee some kind of cast iron, will not tolerate fatigue stress and hence has almost no tolerance to misalignment.
That explains why the camshaft bearings on the head are machined as one piece and the upper half moons are not supplied as spares.
Best regards
JAP


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Lost compression in back three cylinders 2854237993 1988 K100RS SE/ABS
    

enzo

enzo
active member
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Number two cylinder bad. Leak down test shows 100% leakage. Bad news.


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

martyman

martyman
Silver member
Silver member
I'd buy a lottery ticket...

    

12Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Thu Jun 05, 2014 10:59 pm

enzo

enzo
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active member
Air leaking out the air intake valve. Can hear the air blowing out the throttle body on leak down test. Piston top looks okay. Now hoping for just a head rebuild.  Tear down time.


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

13Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Thu Jun 05, 2014 11:06 pm

kartooo

kartooo
Silver member
Silver member
in the past i have seen cars the blew head gaskets because of overheating.
the head was planed down at a machine shop to make it flat again.
but, the head was warped and with miles and time the cam had to flex.
eventualy the cam broke.
something else is wrong there.
you can't over rev it, the controler won't allow it ....
i'd replace the head, e bay is full of them at a reasonable cost.


__________________________________________________
85 k100rt current
04 vulcan 1500 classic sold
07 bonneville black sold
05 fjr1300 sold
04 r1150rt sold
91 k100lt sold
r80rt sold
85 K100 sold
    

14Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Thu Jun 05, 2014 11:21 pm

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
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Kartoo has sound advice. Either a complete head including the valves, springs and camshaft assembly from eBay or even a complete engine. Plenty of them out there. I would expect the inlet valves on all 3 cylinders to be gone as well. Unlikely to have piston damage.

I am still curious as to the cause, but if you figure over revving because of missing a gear then that's fine. But according to the Clymer it shouldn't over rev unless a missed gear is too quick for it to cut the engine revs.


__________________________________________________
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 now 98,780 miles
1983 K100RS 0011171 Fricka 29,495 miles Damn K Pox Its a Bat outta Hell No 32,600 miles
    

15Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Thu Jun 05, 2014 11:22 pm

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
Kartoo has sound advice. Either a complete head including the valves, springs and camshaft assembly from eBay or even a complete engine. Plenty of them out there. I would expect the inlet valves on all 3 cylinders to be gone as well. Unlikely to have piston damage.

I am still curious as to the cause, but if you figure over revving because of missing a gear then that's fine. But according to the Clymer it shouldn't over rev unless a missed gear is too quick for it to cut the engine revs.


__________________________________________________
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 now 98,780 miles
1983 K100RS 0011171 Fricka 29,495 miles Damn K Pox Its a Bat outta Hell No 32,600 miles
    

16Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Thu Jun 05, 2014 11:54 pm

marten

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I have a spare engine near Santa Barbara from a 85 K100RS
Contact me if you need some parts.

M

    

17Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Sat Jun 07, 2014 12:35 pm

enzo

enzo
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Took it apart this morning. Cylinder and pistons look good. Now just need to find a machine shop and get the head checked out. Broken cam very hard to turn with timing chain removed. Can't see any cracks or signs of binding. Valves look okay to me but was leaking badly.
Lost compression in back three cylinders 20140607_073520Lost compression in back three cylinders 20140607_073544Lost compression in back three cylinders 20140607_073616Lost compression in back three cylinders 20140607_073627


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

18Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Sat Jun 07, 2014 12:50 pm

enzo

enzo
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active member
Looking at the pictures it looks like two valves hit the pistons.


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

kartooo

kartooo
Silver member
Silver member
9 on ebay right now at $99 or less with free shipping.
slap one on with a new head gasket and enjoy your summer.
you gonna pay that in labor at a machine shop.....

i bought a complete engine in the winter for $175 with trans/starter/alt



Last edited by kartooo on Sat Jun 07, 2014 2:00 pm; edited 2 times in total


__________________________________________________
85 k100rt current
04 vulcan 1500 classic sold
07 bonneville black sold
05 fjr1300 sold
04 r1150rt sold
91 k100lt sold
r80rt sold
85 K100 sold
    

kartooo

kartooo
Silver member
Silver member
@enzo wrote:Looking at the pictures it looks like two valves hit the pistons.

#2 intake for sure Lost compression in back three cylinders Icon_mad


__________________________________________________
85 k100rt current
04 vulcan 1500 classic sold
07 bonneville black sold
05 fjr1300 sold
04 r1150rt sold
91 k100lt sold
r80rt sold
85 K100 sold
    

enzo

enzo
active member
active member
@kartooo wrote:9 on ebay right now at $99 or less with free shipping.
slap one on with a new head gasket and enjoy your summer.
you gonna pay that in labor at a machine shop.....

Good point. Looks like the best option.


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

22Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Wed Jun 11, 2014 11:08 pm

enzo

enzo
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active member
I bought a complete 85 motor from a wrecked bike. 200$ from A And M cycle traders. They had three and all looked pretty beat. It was very tired looking and appears to have MANY more miles than mine. Lost compression in back three cylinders 20140609_145103


 I pulled it apart and took out the intake cam and a couple valves and rebuilt my head. Now I have some spare parts as well. Did not want to buy the valve compression tool so I cut and old socket and used a press. My first valve job was very educational! Cleaned up all the valves and lapped the seats. Now I am just waiting for a head gasket and bike will be back on the road. Lost compression in back three cylinders 20140611_171749
Lost compression in back three cylinders 20140611_171802 affraidLost compression in back three cylinders 20140611_181745


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

23Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Wed Jun 11, 2014 11:22 pm

japuentes

japuentes
Life time member
Life time member
Hi there, lapping the seats changes the valve clearances, I would check them and get the required shims.
Hope this helps
Best regards
JAP


__________________________________________________
Lost compression in back three cylinders 2854237993 1988 K100RS SE/ABS
    

24Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Wed Jun 11, 2014 11:23 pm

kartooo

kartooo
Silver member
Silver member
great !!
hall effect sensor still there ?
if so your ahead of the game.
looks like you got yourself a crankcase vent hose too.
like your valve spring compressor.


__________________________________________________
85 k100rt current
04 vulcan 1500 classic sold
07 bonneville black sold
05 fjr1300 sold
04 r1150rt sold
91 k100lt sold
r80rt sold
85 K100 sold
    

25Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Wed Jun 11, 2014 11:28 pm

RicK G

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Before you even start it check the line bore of the cam journals. I will bet London to a brick the head is warped and that is what has broken the cam. Don't use the original head or you stand a very good chance of it happening again.
Put a cam into the head without the valves and try to turn the cam, more than likely it will be very hard to turn.  It should turn very freely with the caps tightened down.
Also check that the correct caps have been used as they are matched to the journal in the machining process and if they are mixed up it will bust a cam or chew a journal out.


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

26Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Wed Jun 11, 2014 11:32 pm

kartooo

kartooo
Silver member
Silver member
@RicK G wrote:Before you even start it check the line bore of the cam journals. I will bet London to a brick the head is warped and that is what has broken the cam. Don't use the original head or you stand a very good chance of it happening again.

that's what i stated in post #13


__________________________________________________
85 k100rt current
04 vulcan 1500 classic sold
07 bonneville black sold
05 fjr1300 sold
04 r1150rt sold
91 k100lt sold
r80rt sold
85 K100 sold
    

27Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Thu Jun 12, 2014 12:38 am

enzo

enzo
active member
active member
@RicK G wrote:Before you even start it check the line bore of the cam journals. I will bet London to a brick the head is warped and that is what has broken the cam. Don't use the original head or you stand a very good chance of it happening again.
Put a cam into the head without the valves and try to turn the cam, more than likely it will be very hard to turn.  It should turn very freely with the caps tightened down.
Also check that the correct caps have been used as they are matched to the journal in the machining process and if they are mixed up it will bust a cam or chew a journal out.

Thank you, I will pull the valves tomorrow and check it out. Hope your wrong!!


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
You need to do as Rick G suggested. If the cams have any resistance to turning then you have a problem. They have no resistance to the stresses of a warped head.

Curiously I was having coffee on Tuesday with a friend who is ex BMW and working on bikes for about 45 years!. He jokingly slags me off about the K but when I asked him about engine reliabilty his comment was that the only time he had to work on the engines themselves was due to crash damage. Never an engine failure!

He was rebuilding a final drive on a GS. A very simple job if its done when the bearing starts to wear and not left until it breaks up.


__________________________________________________
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 now 98,780 miles
1983 K100RS 0011171 Fricka 29,495 miles Damn K Pox Its a Bat outta Hell No 32,600 miles
    

29Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Thu Jun 12, 2014 10:19 pm

enzo

enzo
active member
active member
It's warped. Intake cam has  resistance to turning. Not bad. But 10 times more than the exhaust which turns very freely. Binds at main journal by cam chain. Remove it and it spins fine. 

Time to do a valve job on the other cylinder. Thanks for the heads up guys.


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

30Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Thu Jun 12, 2014 10:30 pm

kartooo

kartooo
Silver member
Silver member
probably overheated sometime in it's life.
after repeated flexing fatigue takes over and the cam breaks.
i've seen it with flywheels. trans to block missing a dowel.
or just a tab from a wire harness between the bell housing and block.
takes a few weeks, sometimes months and the flywheel develops cracks from flexing.


__________________________________________________
85 k100rt current
04 vulcan 1500 classic sold
07 bonneville black sold
05 fjr1300 sold
04 r1150rt sold
91 k100lt sold
r80rt sold
85 K100 sold
    

31Back to top Go down   Lost compression in back three cylinders Empty Re: Lost compression in back three cylinders on Sun Aug 03, 2014 12:52 pm

enzo

enzo
active member
active member
New Head gasket finally came from Germany, Got it all back together and was surprised that it runs perfectly!
I do have a new oil leak where you feed the wires down to the oil pressure sending switch. Have pulled the cover for the ignition pick up and it does not seem to be coming from the oil seal. Going to ride it a bit and see how it goes.

Thanks for the help Gentleman.


__________________________________________________
1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

kartooo

kartooo
Silver member
Silver member
i love happy endings  Smile


__________________________________________________
85 k100rt current
04 vulcan 1500 classic sold
07 bonneville black sold
05 fjr1300 sold
04 r1150rt sold
91 k100lt sold
r80rt sold
85 K100 sold
    

Inge K.

Inge K.
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VIP
Well done  Lost compression in back three cylinders 112350  .


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

charlie99

charlie99
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+1  
good result

happy riding !


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OLost compression in back three cylinders Au-log10

"redframe" rs "bitsa"  with many contributions from the k100 community ,,with many thanks
    

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