BMW K bikes (Bricks)

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JiiPee63

JiiPee63
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Hi there, 

While putting everything back in place in the engine (just covers were out), I noticed that one of the valve cover bolts was not tightening at all. I used a torque wrench (9NM) to tighten them. I thought to sort this out a bit later but ..okay.. I could not help it. So, I took the valve cover out and realized one bearing clamp having cracks (see pics). Also saw that there were helicoil type threads attached to a bolt. So, someone had fixed threads in the past. By the way, I did not fired up the engine since last autumn. It has been in a warm garage all the time. 

Another odd thing is that metal structure at the bottom of threads hole looks like the surface of the moon or cheese. It is not like machined. When we look at the bearing surface things turns out to be even more peculiar - pitted surface! I do not feel any scratches with my finger nail but I do feel those pits. Do you have any idea what makes those holes? Corrosion, lack of lubrication, casting quality or something else? Camshaft is visibly in a good condition. I did check other clamps and there are no problem with them. Only this one (n:o Cool is scrap. 

Anyway, I just ordered a replacement (used) from Germany. 
An issue with a camshaft bearing clamp K100_c12
An issue with a camshaft bearing clamp K100_c11
An issue with a camshaft bearing clamp K100_c10


__________________________________________________
1986 K100RS 0089906 (Black 608)
Ex - 1984 K100RS (white), 1986 Suzuki GR650
    

Point-Seven-five

Point-Seven-five
Life time member
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I suspect that the voids you see were cast into the part.  It seems that BMW had/has a problem with porosity in their castings.  The black coating inside the valve cover and the oil sump is there to prevent oil from seeping through the parts.  It's also been said that the finish on the wheels is not just cosmetic, but helps seal against air leaks through the rims.  

Your broken cap is a great warning about always using a torque wrench to tighten the valve cover screws.  It appears that someone in the past over tightened that screw and cracked the boss on the cam bearing cap.

You do know that those caps are matched to the head and aren't just a bolt on for a repair part?  I would use some Plasti-Gage to make sure there is proper clearance between the cam and your replacement bearing cap.  You may have to adjust the fit with shims or removing a little from the faces where they contact the cylinder head.  You don't want the cap pressing down on the camshaft or allowing an overly loose fit.  Maybe someone here will chime in with some advice on how to fit your "new" bearing cap.


__________________________________________________
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
    

92KK 84WW Olaf

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You can't just replace that cap, that's likely to leave you a broken camshaft or destroy the head. AFAIK it's line bored. 

But there is a mod done for a repair to overcome this event and I think is sidecar Paul came up with it. I have an idea it is a bridge piece.


I don't even think you need as much as 9NM but to prevent it happening it's a good idea to replace the soft washers so less torque is needed. Old ones get hard. 
 
That bearing cap is well goosed. Any photo of the camshaft bearing surface?


__________________________________________________
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 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 39.885miles.

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
    

RicK G

RicK G
admin
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Don't be concerned about the bearing surface I have seen it before and as .75 said it's part of the casting before machining.
To fix it remove the remaining part of the tower and make this out of steel.
An issue with a camshaft bearing clamp Cam_bl10


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

Suzi Q

Suzi Q
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It is certainly the case that the heads and caps are line bored and therefore 'matched'. It always surprises me to see heads sold without caps, and vice versa on oohbay....oh well!

However....these are old bikes and some fudging is always worth trying and acceptable if it works. I haven't done this yet because I haven't been on the OP's situation, but I would be happy to try things with a swapped in cap. You'd have to strip the head to do this because it would involve staged assembly/torquing of the caps with just the cam installed - no valve gear. Feeling for resistance/checking for play would tell you if it was going to be okay. There are ways.

That said, I like the look of the 'steel bridge' fix.


__________________________________________________
Sometimes I'm not really Suzi Quatro.
    

JiiPee63

JiiPee63
active member
active member
Hi,

I felt myself quite a newbie when not remembering that clamps and the head should match. Thanks for a very valuable quidance. Very Happy

I made today a steel bridge as Chris846 and some others suggested, according to a pic RicK G posted. Mine is not beautifully constructed, but it is working. I used my "precision" tools like a small angle grinder, a file and so on and put the old clamp back there with assembly lube. I thought it is scrap due to pits on a bearing surface. Anyway, two used clamps (or caps?) are on the way already. According to most of the comments I do understand that they are useless for me. Not a big thing. Learnt again. I should think first and then act. Not vice versa An issue with a camshaft bearing clamp 652573 . 
An issue with a camshaft bearing clamp Steel_10


__________________________________________________
1986 K100RS 0089906 (Black 608)
Ex - 1984 K100RS (white), 1986 Suzuki GR650
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I would like say that looks a lot nicer than anything that would come off of my workbench! Nice job!


__________________________________________________
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
    

JiiPee63

JiiPee63
active member
active member
@92KK 84WW Olaf wrote:That bearing cap is well goosed. Any photo of the camshaft bearing surface?
I didn't take a picture of it but I did check visually all caps and camshaft necks. The neck of this point looks exactly like the others - no scratches visible. I wondered this after seeing the pits. Could it be just casting issue or something? There were no abnormal noise or something last time the engine run.

Thanks, Point-Seven-five  An issue with a camshaft bearing clamp 112350


__________________________________________________
1986 K100RS 0089906 (Black 608)
Ex - 1984 K100RS (white), 1986 Suzuki GR650
    

92KK 84WW Olaf

avatar
Life time member
Life time member
@JiiPee63 wrote:Hi,

I felt myself quite a newbie when not remembering that clamps and the head should match. Thanks for a very valuable quidance. Very Happy

I made today a steel bridge as Chris846 and some others suggested, according to a pic RicK G posted. Mine is not beautifully constructed, but it is working. I used my "precision" tools like a small angle grinder, a file and so on and put the old clamp back there with assembly lube. I thought it is scrap due to pits on a bearing surface. Anyway, two used clamps (or caps?) are on the way already. According to most of the comments I do understand that they are useless for me. Not a big thing. Learnt again. I should think first and then act. Not vice versa An issue with a camshaft bearing clamp 652573 . 
An issue with a camshaft bearing clamp Steel_10
That's it! No camshaft or line boring issues. Not much torque needed on the cam cover bolts, err on the light side.


__________________________________________________
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 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 39.885miles.

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
    

10Back to top Go down   An issue with a camshaft bearing clamp Empty Cam mount Sun Apr 11, 2021 5:04 pm

Kr4mo

Kr4mo
active member
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@Point-Seven-five wrote:I suspect that the voids you see were cast into the part.  It seems that BMW had/has a problem with porosity in their castings.  The black coating inside the valve cover and the oil sump is there to prevent oil from seeping through the parts.  It's also been said that the finish on the wheels is not just cosmetic, but helps seal against air leaks through the rims.  

Your broken cap is a great warning about always using a torque wrench to tighten the valve cover screws.  It appears that someone in the past over tightened that screw and cracked the boss on the cam bearing cap.

You do know that those caps are matched to the head and aren't just a bolt on for a repair part?  I would use some Plasti-Gage to make sure there is proper clearance between the cam and your replacement bearing cap.  You may have to adjust the fit with shims or removing a little from the faces where they contact the cylinder head.  You don't want the cap pressing down on the camshaft or allowing an overly loose fit.  Maybe someone here will chime in with some advice on how to fit your "new" bearing cap.
I would get some plastigauge and measure the stock one, then measure the replacement and get it as close as possible with either shims or trimming.  Be sure to do each side the same to keep the new one aligned to the cam.

    

JiiPee63

JiiPee63
active member
active member
Thanks Very Happy . Just wondering which measuring range I should consider in case of a clamp change? There are packages (5-10 strips) for 0.025-0.175mm, 0.100 - 0.125mm and some packages with greater tolerances.


__________________________________________________
1986 K100RS 0089906 (Black 608)
Ex - 1984 K100RS (white), 1986 Suzuki GR650
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I would go for the .025-.175mm.  I can't imagine the clearance being large enough to use the larger size.  

I would go a long way toward using the old cap with the bar for holding the valve cover screw before trying to use a replacement.  A replacement will mess with the fit of the cam bearing at that spot, and will always be a weak spot in the mechanical integrity of the engine. Fitting that new cap is a desperation repair.


__________________________________________________
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
    

RicK G

RicK G
admin
admin
I would not even consider using anything but the original cap and the repair you did. It is highly unlikely that either of the caps you bought would fit let alone be a good fit and you would most likely end up with a damaged cylinder head that would be a very expensive fix. The repair you did would be stronger than the original cap and the small imperfections are of no concern.


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

JiiPee63

JiiPee63
active member
active member
Hi, thanks An issue with a camshaft bearing clamp 1f44d.  Got used parts this morning. I noticed small cavities at both of them. So, these parts being as a reference, I believe there shouldn't be any problem with the original one.


__________________________________________________
1986 K100RS 0089906 (Black 608)
Ex - 1984 K100RS (white), 1986 Suzuki GR650
    

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