points in a can - shaft play

Discussion in 'Airheads' started by Cdubs, Nov 15, 2015.

  1. Cdubs

    Cdubs made for adventure

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    #1
  2. 190e

    190e Long timer

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    There is more movement than I've observed but that's what the outrigger bearing is for.
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  3. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    These guys sell an after market front camshaft bearing: http://www.bmwboxersupplies.com/camshaft-bearing-cast-ironbronze-lining-p-290.html?language=en

    [​IMG]

    Although, I'm not quite sure exactly how this would fit in the engine casing. I had thought the cam bearings were installed (pressed) in the engine casing, like most engines. Apparently not. Installation requires removing the camshaft.

    Edit: BMW sells that part, which they call a flange, for considerably less: http://www.maxbmwmotorcycles.com/fiche/PartsSearch.aspx?&searchtype=partnumber&parts= 11 31 1 250 251
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  4. headtube

    headtube Been here awhile

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    A little play is normal. I haven't measured the runout but my points can (the same as yours with condenser on the side) has simalar play. That is why you always adjust the points with the outrigger bearing installed.

    Perhaps check your cable routing, inspect your idle jet and float bowl adjustments.
    #4
  5. Disston

    Disston ShadeTreeExpert

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    You have a problem if the timing is uneven. It can be seen with a timing light but sometimes it is not really that evident. Timing can be correct for one side but advanced or retarded on the other. makes for a funny running machine. You have to look carefully at the timing marks with a timing light and try to see it there are two marks instead of one. Raise and lower the engine rpm to watch for more than one mark. If the marks are close enough to each other it is manageable but if spread too far apart it must be fixed. This is more common on earlier bikes with duplex timing chains but I've seen reports of the problem with simplex chains and this may be the source of that complaint.
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  6. 190e

    190e Long timer

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    Points in can is very good to start with precisely because of that outrigger bearing but for anyone seeking perfection in terms of equal timing there is a very small amount of clearance between the outrigger plate and the recess in the end of the can. On mine a 2 thou feeler gauge will fit in the gap which is enough to allow the timing to be a degree or so off between cylinders. A little experimentation in centralising the plate or moving that 2 thou offset from one side of the can to the other will get you close to perfection.
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  7. Cdubs

    Cdubs made for adventure

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    What is the outrigger bearing? I usually just set a high point on the points cam and adjust from there.
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  8. Cdubs

    Cdubs made for adventure

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    Trying to wrap my head around this, why would there be two marks?

    do you mean the bit on the back of the points can that fits into the cam? I forgot that it goes slightly sideways, so moving it back and forth could make a difference?
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  9. Disston

    Disston ShadeTreeExpert

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    The four stroke engine needs two revolutions of the crankshaft to complete a cycle of four strokes. Because there are two cylinders one of them will be on compression on each revolution of the crank. So the ignition fires for the left side on one revolution and then for the right side the next. Both coils fire each time but only one cylinder is getting ignition. So you have two firings of the ignition every two revolutions of the crank. When these are not matched one cylinder can be timed advanced or retarded more than the other and it makes for strange vibrations. It is not a rare problem with duplex camshafts but I'm not sure if simplex cams, like your bike, can get this problem or not.

    The problem is called a Ghost Image of the timing marks when observed with a timing light because the timing mark will be at one mark for one cylinder and at another for the other cylinder. There can be two images when trying to adjust timing. You may only notice the double image if you carefully observe the timing mark moving while varying the rpm.

    I don't know if the looseness you have shown is going to cause this problem. What I have heard is a few simplex camshaft images with the Ghost Image problem. I just have never figured out what the cause was. So my concern that I have tried to pass on is to look for the Ghost Image because it could be there. Or I think it could. Not saying it will be.

    Hope this explains some about what I was getting at.
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  10. Solo Lobo

    Solo Lobo airhead or nothing Supporter

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    The outrigger bearing is part of that chunk of aluminum on the lower right side of the picture below. It supports the shaft you are wiggling, and is there to minimize wiggle. You need to leave that in place when you set your point gap.

    Well, that is actually a picture of the hall sensor can, but the outrigger is about the same in the points can

    [​IMG]
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  11. Solo Lobo

    Solo Lobo airhead or nothing Supporter

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    Here's a better shot of the outrigger in place

    [​IMG]
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  12. patrkbukly

    patrkbukly Life at 10,000 feet

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    Yes the outer plate as pictured above is what eliminates that movement.
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  13. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    After looking at the 2002 edition of the Clymers manual, replacing the bearing flange does not require removing the camshaft! Also, the camshaft nose is not what contacts the points, so this bearing and the cam don't need to be touched as noted in this thread. For the '78 and earlier models, if that much play was found then the cam bearing would need to be replaced. Good luck!
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  14. bmwrench

    bmwrench Long timer

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    Neither points gap nor timing should be checked without the the out rigger plate instlled. I suspect that there is nothing wrong with that can.

    To address a thread diversion: The front camshaft bushing can not be replaced without removing the cam. The bushing is behind the cam sprocket, which is pressed on rather precisely.
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  15. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    So, the claim is made that there is no way to remove the cam gear while it's in the engine? I rather doubt that. I would take my chances with a cycleworks tool intended for that use: http://www.cycleworks.net/index.php?main_page=product_info&cPath=29_33_51&products_id=373

    [​IMG]

    True, the Clymers (and Haynes and BMW) manuals describe removing the camshaft to remove the sprocket. That is described to be done after the engine is removed from the frame. I think there is also some description of removing the cam with the crankshaft simultaneously on some models. As usual, there is the hard way and the smart way to get the same job done.
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  16. 190e

    190e Long timer

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    Are you saying you don't have the outrigger bearing plate ?

    If so and the engine has been run without it that would explain why you have play and now possibly wear in rear bearing of the can.
    The play demonstrated in the video has nothing to do with camshaft bearings so don't be concerned about the camshaft bearing that's been mentioned.
    The rational for moving from camshaft mounted points to points in a can was that the can had it's own independent bearings.
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  17. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    I may be cluttering this thread more.... but for the points in a can, the camshaft does not actuate the points directly. The points contact a shaft which is inside the distributor can which has a bearing. Solo Lobo posted photos of the configuration. This is what some call the 'outrigger' bearing.
    [​IMG]

    This is a link to the bearing cover, which has the 'outrigger bearing', as sold by BMW: http://www.maxbmwmotorcycles.com/fiche/PartsSearch.aspx?&searchtype=partnumber&parts= 12 11 1 243 923

    The bearing cover needs to be installed to remove the play shown in the video. It's part #3 shown in the fiche:

    [​IMG]
    #17
  18. bmwrench

    bmwrench Long timer

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    Cool. Now, let's see you put the sprocket back on.
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  19. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    It Woiks Like a Charm. The trick is installing the cam sprocket with the spec'd .005" axial (end) play.

    1. Make sure the camshaft is all forward so there is zero play between the cam and rear of the front cam bearing. Loosen or not loosen the valve adjusters-- doesn't seem to matter.

    Levering the camshaft forward? Ideally, best time is before pull the sprocket-- lever it with a big screwdriver/prybar against the case. If the cam sprocket is removed, use Vise-Grips :eekers . Just cushion/protect the sprocket nub on the cam with cardboard or leather strap or nylon webbing and grip it with Vise-Grips and lever against the VGs. If you loosen the valve adjusters, or if the heads are off, you may bven be able to move it forward with bare hands.

    2. Pull the old sprocket with the Cycleworks tool.

    sprock12.jpg

    3. Using .004" or .005" shim stick, make a shim spacer or a "fork" and place it on the front of the cam bearing.

    sprock23.jpg

    4. Heat the new cam sprocket to 250 degF and very quickly and decisively slide it onto the cam stub. If it doesn't seat down firmly, pull the sprocket and try again. You may have to heat the sprocket a tad more or run faster.

    sprock24.jpg

    5. Remove the shim and you should have the proper axial play on the cam bearing. You can double-check it with a dial indicator. I had a hair more, but not enough to worry about.

    sprock29.jpg

    6. Alternatively, you could NOT use that shim fork and just install the sprocket with ZERO endplay, and use the puller to pull the sprocket out and give the req'd endplay, measuring with a dial indicator. This is a crapshot-- you may end up pulling, heating and reinstalling the sprocket a half-dozen times to get it right.

    You _could_ pull the camshaft if you needed to inspect it, etc, but if you don't need to, this is a way to do it without needing to go that far. Your call.

    I'll leave it up to the reader to figure camshaft removal, and setting the endplay per the factory method.

    --Bill
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  20. Cdubs

    Cdubs made for adventure

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    I do have the outrigger bearing plate, just didn't know the name for it. Bike is running better, going to re check/adjust gap with outrigger in place.
    #20