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Thread: Timing and points problem 1976 R90/6 not starting.

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    Timing and points problem 1976 R90/6 not starting.

    I recently replaced my points on my r90/6 and can't seem to advance the timing enough to get the bike to fire up. While using the alligator clip to light bulb method to set the timing initially I can only turn the plate enough to turn the bulb on about 3 cm from the S marks and on the other end the bulb lights up at the F. A friend of mine suggested i skipped a tooth on the timing chain. It's almost like the range of adjustment has moved. Any Ideas? Thanks.

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    Administrator 20774's Avatar
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    Go back to your points gap...be sure you're setting it at the proper place on the cam rotation. And don't be afraid to change the gap away from the nominal of 0.016". It can be as low as 0.012 or up to 0.022 or thereabouts. Gap is not that critical on a two-cylinder machine. The timing is, though. A small change in gap makes a big change in the ability to rotate the plate. Just think about what you need in terms of when the gap should open relative to how the cam is turning...you'll figure out if you need to open or close the points gap a touch.

    Don't consider filing the points plate holes...the bike was designed properly and having wider holes is not the answer.

    Also be sure you don't have a set of the Chinese points that were floating around...I think the rubbing block was way too tall. If you have them, you can't get the bike to time at all.

    The gap is more critical on a 4-6-8 cylinder engine because the time that the points are closed is coil saturation time. If you get the gap too wide, the time of points closure goes down, which reduces coil saturation, which reduces strength of spark.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    Registered User lmo1131's Avatar
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    There's a lot going on in a restricted space when setting points and it's really easy to set them too wide. And get one of these little gems from Northwoods Airheads. for setting your points gap. Worth every Pfennig.



    I'd bet a yuan [$0.16 USD] that you've got a set of Chinese-made points.

    German on the left. Chinese on the right.



    source: Bavarian Cycle Works
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    #4869 DennisDarrow's Avatar
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    +3 on the gap. Does it every time. You live and learn by doing it yourself and feel the pride of your work when it does fire right up. Hang in there Bud, you are on the right track.........Good luck and God bless.......Dennis

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    Registered User toooldtocare's Avatar
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    +4 on the points gap. I had to drop mine down to about 10 on my R90S. Ran fine that way.

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    Thanks, great help.

    Quote Originally Posted by toooldtocare View Post
    +4 on the points gap. I had to drop mine down to about 10 on my R90S. Ran fine that way.
    These are all a great help. Please excuse my ignorance but what does "+4" mean exactly?

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    Administrator 20774's Avatar
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    Quote Originally Posted by pszyjka View Post
    These are all a great help. Please excuse my ignorance but what does "+4" mean exactly?
    It's internet shorthand for "I'm the 4th person to agree with this."
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    Tall block on chinese made points.

    What do you think the success rates are on filing the block down on this Chinese made item are? Little by little perhaps? This tall block theory seems to be the one, I for sure have the Chinese made points. Thanks. you guys are such a great resource and community.

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    Registered User lmo1131's Avatar
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    I for sure have the Chinese made points.
    Then I would for sure return them ... Most dealers won't return "electrical" parts but these dealers have to learn that this junk doesn't work, and "we" are tired of bearing the expense of having it sold to us. If you file on them then the dealer for sure will not accept them; as it is you could "argue" that the part is defective, and you want a refund. I would ask for shipping charges to be refunded as well.

    I'd spring the $22 for a set of German-made "Noris" points > 12111243556.
    Last edited by lmo1131; 05-06-2013 at 03:47 PM.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    #4869 DennisDarrow's Avatar
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    Yes, do try to return them if you can. Filing them enough to make a difference will probably go through the coating that is on the face of the points so that the metal/coating doesnt pit so easily with the spark being produced. This is very thin and when you do go through it, enough to make a difference in timing, you are very much causing pits and erosion in just a few short thousands of miles. A good set of points will last MANY MANY MANY thousands of miles.........God bless......Dennis

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    Administrator 20774's Avatar
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    Dennis -

    I think he's considering filing the rubbing block, not the face of the points themselves. Filing the points themselves doesn't buy very much...as you suggest, doing do will quickly make them useless. But lowering the rubbing block could bring them back into spec. Matt Parkhouse had an article in the September 2010 ON about the problem...he showed the Chinese and BMW points side-by-side.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    Registered User lmo1131's Avatar
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    From 2009 > http://www.bmwmoa.org/forum/showthre...e-Points-Alert


    Genuine BMW



    The low-price spread. Glaringly obvious, isn't it.

    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  13. #13
    Registered User ezwicky's Avatar
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    i have the same issue and my points are just like the "good" ones in the photos. i had to lengthen the slots to get the "S" mark in the center of the window. at 3k, the "F" mark is centered in the window and stays there as RPM increases. when the "OT" mark is centered in the window, one side of the top end is at full compression.

    so the flywheel looks to be correctly oriented, and i have the correct points (have tried two sets, the one that's installed now is from max BMW and offered as "noris" but they both have the shorter rubbing block).

    i am using the northwoods tool to adjust the points gap (as shown in a post further up the page).

    so i wonder what else i should be looking at as a possible cause of the same issue as the original poster?

    -eric
    BMWMOA #182796

    '76 R90/6

  14. #14
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    Quote Originally Posted by ezwicky View Post
    so i wonder what else i should be looking at as a possible cause of the same issue as the original poster?
    You have to change your gap. I realize the Northwoods tool sets a very precise gap. There might be a number of reasons why that specific gap (approx. 0.016") doesn't work...one is that the points units are not highly machined parts so there will be some variation in them. A small change in points gap makes a much bigger change in timing than by simply rotation the points plate.

    There should be no need to open up the slots in the points plate...that is just putting a bandaid on things. Unfortunately, the Northwoods tool drives you down this path because you're locked into the fixed dimension it has.

    There is an overlap on points gaps and point plate rotation that will work just fine. But if you fix the points gap measurement, you may not be able to work the other parameter.

    The solution is to use the manual method to change the points gap. Figure out if the gap needs to be bigger or smaller based upon what is happening with the engine rotation and the lift on the points cam lobe. Use the Northwoods tool to set the stock gap. Then just tweak the gap the right way a hair and tighten it down. Reinstall and check your timing. If too far or not enough, remove everything and tweak it a bit more. Pretty soon you'll begin to get a feel for how much you need to do it for the movement in timing you need.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  15. #15
    Registered User ezwicky's Avatar
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    thanks kurt. there is a section in the chitech tune-up manual about checking the gap at two points on the cam, 180 degrees apart. i will re-visit that this weekend.

    -eric
    BMWMOA #182796

    '76 R90/6

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