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Thread: no compression at all either cylinder!

  1. #46

    flywheel installed wrong?

    Quote Originally Posted by rxcrider View Post
    Sorry - I misunderstood and thought you couldn't see OT in the window at all. As always, there is more than one way to get where you are going.

    The key is to find out if the valves are doing what they should when the pistons come to TDC. Assuming they are not, if both sides are wrong by the same amount at the same time, I'd lean toward the issue being behind the front housing / alternator support. (That is a joy to remove and install) If one side is right and one side is wrong, the problem may be isolated to the cam chain on one side.

    Hopefully, when the pistons come to TDC, OT is showing in the window. If not, the flywheel is installed wrong and you can't use the lock pin to hold the engine at TDC for reassembly.
    After much thought, the only way to have a good leak down result at tdc but no compression is a valve must be opening while the piston is traveling up the bore, releasing the compressed air. Assuming the engine wasn't disassembled and reassembled wrong in the guys garage I bought it from, it has lost it's cam timing. I think the problem may be under the front cover, stretched timing chain perhaps, or it could have skipped on the sprocket due to bad chain tensioner(s) or both.
    I'll have to look and see if the timing marks still line up with the cam sprocket markings.
    Since I already have the exhaust manifold, tank and plastic off, could you tell me what else might be a challenge in removing the front cover. Is the alternator support bracket hard to remove?

  2. #47
    Pepperfool GSAddict's Avatar
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    Quote Originally Posted by rxcrider View Post
    ...until someone ignores it and just runs the bolts down with compete disregard for alignment, driving the dowel back into the bore it was pierced from. I'm not saying this is likely and I never would have thought of it until I saw one. On the other hand, we don't know the history of the bike and it is a 5 minute check at most to know whether or not you can trust the OT mark. Since that mark may be used to check the cam timing, I think it is prudent to verify it.



    clearly, they slipped the clutch into oblivion as well
    Some people should not be allowed near tools.
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  3. #48
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    Quote Originally Posted by edheiser View Post
    After much thought, the only way to have a good leak down result at tdc but no compression is a valve must be opening while the piston is traveling up the bore, releasing the compressed air. Assuming the engine wasn't disassembled and reassembled wrong in the guys garage I bought it from, it has lost it's cam timing. I think the problem may be under the front cover, stretched timing chain perhaps, or it could have skipped on the sprocket due to bad chain tensioner(s) or both.
    I'll have to look and see if the timing marks still line up with the cam sprocket markings.
    Since I already have the exhaust manifold, tank and plastic off, could you tell me what else might be a challenge in removing the front cover. Is the alternator support bracket hard to remove?
    Not hard, just tedious.
    The telelever needs to be moved forward to get it out.
    The pivot shaft needs to be pulled to do that.
    Be sure to reinstall from the correct side if the heads are off. The nut goes on the right side.
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  4. #49
    Registered User rxcrider's Avatar
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    Since the rest is relatively easy to check compared to pulling the alternator support, I'd still take a few minutes to verify the timing of everything you can currently get to. Even if the entire issue turns out to be up front, I'd rather let the results push me in that direction than jump there on a hunch.

    If you do end up pulling the alternator support off, the front crank seal is set to a depth because there is no seat to stop against. It is also easy to cut it going on or off so there is a nice little BMW seal driver with an installation sleeve / cone which makes life easier.

  5. #50

    ack!

    Quote Originally Posted by rxcrider View Post
    Since the rest is relatively easy to check compared to pulling the alternator support, I'd still take a few minutes to verify the timing of everything you can currently get to. Even if the entire issue turns out to be up front, I'd rather let the results push me in that direction than jump there on a hunch.

    If you do end up pulling the alternator support off, the front crank seal is set to a depth because there is no seat to stop against. It is also easy to cut it going on or off so there is a nice little BMW seal driver with an installation sleeve / cone which makes life easier.
    I just read the chapter on removing the alternator.........gee, that does sound like fun!
    It would be relatively easy to check the sprocket timing if I could get the flywheel to stop on OT in the center of the hole. I could pop off the valve covers and either back off the valve adjusters completely or back off the 3 torx bolts securing the cam tower cover or both to relieve any valve spring pressure to see if that's what's causing the problem getting the OT mark to stay in the window. See any problem doing that?

  6. #51
    Enjoy The Ride saddleman's Avatar
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    You can always remove the rocker arms to do a leak down test & then it won't matter where the piston is at in the bore. If the piston is at bottom dead center it just takes a little longer on a leak down test for the gauge to stabilize.
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  7. #52
    Registered User rxcrider's Avatar
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    Quote Originally Posted by edheiser View Post
    I just read the chapter on removing the alternator.........gee, that does sound like fun!
    It would be relatively easy to check the sprocket timing if I could get the flywheel to stop on OT in the center of the hole. I could pop off the valve covers and either back off the valve adjusters completely or back off the 3 torx bolts securing the cam tower cover or both to relieve any valve spring pressure to see if that's what's causing the problem getting the OT mark to stay in the window. See any problem doing that?
    Letting the valves stay closed would be a good thing right about now - greatly reduces the chance of you crashing one into the piston. If you want to back of the three torx screws, you may as well remove the one cylinder head nut as well and remove the rocker arms as suggested by Saddleman. If you do that, I'd put it back together without the rockers and shafts so you can put some tension back on the cylinder head stud rather than relaxing joint for an extended period.

    If you end up pulling the alternator support, you just unbolt the alternator from the front and leave it sitting on top of the motor. You don't actually follow the steps for removing the alternator from above. It is a bit fun moving the suspension arm forward to make enough room to clear the tip of the crank shaft and I don't remember the manual covering those steps.

    This photo and a few more to the right when you follow the link show the alternator support removed from my 1995 R1100RSL. I did this prior to getting the seal installation tool so I installed the new seal off the bike and wrapped the tip of the crankshaft in tape to protect the seal while installing the alternator support.

    Last edited by rxcrider; 05-26-2017 at 07:50 PM.

  8. #53

    I'm about ready to give up

    I am weighing my options, and leaning towards giving up on this bike. It is becoming increasingly obvious to me that this engine is out of time and there is no easy solution. Either the flywheel has slipped due to incorrect assembly, or the timing gear has come out of sync. Either way, even corrected there may be other damage done that would require splitting the cases. This was going to be easy and fun. It is neither.
    I have 4 other motorcycles in perfect running order (that I'm not enjoying because I'm working on this bike), not to mention 5 boats and other vehicles. I'm 73 and perhaps it's time to ease up a little, I'm really beat up today from spending the last 6 days wrenching. My wife is worried I'll croak. I always finish what I start, so it's hard to give up. But as Clint Eastwood said "Dying ain't much of a living boy". I'll think it over.
    Last edited by edheiser; 05-26-2017 at 10:53 PM.

  9. #54
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    Take a time out to collect your thoughts.
    Do something else for a week.
    Come back to it then.
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  10. #55
    Registered User dieselyoda's Avatar
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    Been riding!!

    So, the engine snaps over the TDC, regardless of mark, regardless of cylinder. Easy, peasy to diagnose.

    Put a dial indicator on one intake rocker, turn engine over until you reach max lift. Record the lift, make a mark on the case relative to the crankshaft pulley. Both marks should be easy to see.

    Move dial indicator to the other intake rocker, turn engine over until you have the same lift as what you recorded, marks should line up. If they don't, you have it narrowed to the cam/crankshaft timing.

    After that, the next step is an overlap timing check.
    1997 R1100RT, 1981 KZ 440 LTD, R80RT, R90/6 sidecar, K1100RS,1983 K100RS (Cafe now)

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  11. #56

    ok, now I'm hooked again, and feel rested

    Quote Originally Posted by dieselyoda View Post
    Been riding!!

    So, the engine snaps over the TDC, regardless of mark, regardless of cylinder. Easy, peasy to diagnose.

    Put a dial indicator on one intake rocker, turn engine over until you reach max lift. Record the lift, make a mark on the case relative to the crankshaft pulley. Both marks should be easy to see.

    Move dial indicator to the other intake rocker, turn engine over until you have the same lift as what you recorded, marks should line up. If they don't, you have it narrowed to the cam/crankshaft timing.

    After that, the next step is an overlap timing check.
    That sounds very interesting and doable. I have a dial gauge out on the ranch, my deceased father in law ( lived and worked until he was 91) was a Navy machinist and I have all kinds of metal working and measuring devices I know next to nothing about. OK, I'll take a week off to rest up and try again. Tell me about an overlap timing check please or refer me to a link if possible. Thanks

  12. #57
    Registered User AntonLargiader's Avatar
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    The engine springing past OT, even with the plugs out, seems like the piston is touching a valve.

    For someone who has a basic understanding of how the engine works, it's just not that hard to figure out if the thing is timed right. Remove the spark plugs and valve covers. Rotate the engine until one set of rockers is visibly on overlap, and then use a wooden dowel to feel if the piston is at or very near OT. The other side valves should be slightly loose at this point. See if the cam sprocket arrows agree with where overlap is happening.

    Alternatively rotate the engine to OT based on piston position and then look at the cam sprocket arrows and watch the rockers move.

    There's no need to go under the front cover yet. As long as nothing there is broken, you can fix the timing at the cylinder heads.

    You had a cylinder head off. Re-installing the cam sprocket is something that a lot of people get wrong.
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  13. #58

    long story

    Quote Originally Posted by AntonLargiader View Post
    The engine springing past OT, even with the plugs out, seems like the piston is touching a valve.

    For someone who has a basic understanding of how the engine works, it's just not that hard to figure out if the thing is timed right. Remove the spark plugs and valve covers. Rotate the engine until one set of rockers is visibly on overlap, and then use a wooden dowel to feel if the piston is at or very near OT. The other side valves should be slightly loose at this point. See if the cam sprocket arrows agree with where overlap is happening.

    Alternatively rotate the engine to OT based on piston position and then look at the cam sprocket arrows and watch the rockers move.

    There's no need to go under the front cover yet. As long as nothing there is broken, you can fix the timing at the cylinder heads.

    You had a cylinder head off. Re-installing the cam sprocket is something that a lot of people get wrong.
    I know this is a long thread, and I'm not sure where you came in, so here's the situation now. I can't now nor prior to taking off the head, get the OT mark to stay in the window much less centered in it. It resists like mad, then springs past it. I took off a head to see if the valves were damaged or evidence of one hitting the head, no damage or marks. Since it's not exactly in OT, the cam sprocket markings won't line up. I put the cam sprocket on with the nub in the cam indent, went on easy, and it never left the chain. I don't see how it could be installed incorrectly.
    I have no idea how I would "time it at the cylinder heads" without taking off the front cover to see if all the marks are aligned. Could you elaborate?
    I am working on the premise that the previous owner rode the bike home, parked it in his garage, it wouldn't start in the morning, took off the left valve cover, couldn't see anything broken, left it on the side stand, got oil all over the floor, and listed it for sale because he wasn't much of a mechanic and couldn't afford to take it to a dealer, this in his words. He had ridden it for 8 months, got new tires, and brake pads recently.
    So something is broken or has come out of correct sequence. I have heard of timing chains skipping a tooth or two when they stretch over time. We'll see.

  14. #59
    Registered User AntonLargiader's Avatar
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    Quote Originally Posted by edheiser View Post
    I have no idea how I would "time it at the cylinder heads" without taking off the front cover to see if all the marks are aligned. Could you elaborate?
    It's all in the diagrams posted previously. You need to follow those instructions exactly; they are very good but you have to follow every detail in them. If you are on the wrong OT you will be a half tooth off.

    But, first you can do what I described. Just do whatever you feel like doing to see where piston OT is relative to camshaft OT. Piston OT is when it's closest to the spark plug hole. Camshaft OT is easiest to gauge at overlap, although the diagrams describe it in much better detail. Overlap should happen when that piston is closest to the head. Same with the other side.

    Or, position each camshaft so all valves are closed and remove the sprockets so the crank can turn freely and see what it takes to get smooth, easy crank rotation. Then figure out if the flywheel OT mark is correct. Then reinstall the sprockets per the manual.

    Or, actually figure out where the air is going when you try the leakdown. It's going somewhere.

    If you don't have a feel for how the parts of the engine work together, this will be a hard process.

    I haven't had one apart for a while, but when I do I usually don't bother to zip-tie the chains to the sprockets or anything. I set it up from scratch using the procedure that was posted, and then I KNOW it's right.
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  15. #60

    Trying to understand

    Well, this has been quite an education so far. I had never even sat on a BMW before I got this bike, and had no idea how the pistons, valves and cams worked, or even where the cams/push rods were! I am trying to digest all the information provided by forum members before I proceed, as I'm in no hurry to screw this up. I'm sure some of you could time this engine without removing the front cover, but I would rather see the timing marks in the front than deduce where they are.
    I would also like to see if I can determine why this happened, I think resetting the cam sprockets without seeing the timing marks won't tell me. Working on Japanese bikes is quite different, I took a six cylinder Goldwing engine apart, split the cases, rebuilt the transmission (and it had reverse too) and figured it out. So I am confident I will figure this out eventually. Thanks all for your help.

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