Timing chain replacement, R80RT, 1985

Discussion in 'Airheads' started by Sniper X, Jul 25, 2012.

  1. Sniper X

    Sniper X De Oppresso Liber

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    So by looking at the fisches, it LOOKS like changing the timing chain will be pretty easy. Is there a video or written deal on this by any chance?
    #1
  2. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    The crank nose bearing and sprocket can be a little tricky to pull and needs some heat. Use care not to mung up the crank nose with whatever puller you use. Additionally getting the new master link in from behind the chain is kinda tricky. Use the old master link inserted into the front of the chain to align it and hold it in place and then push it out with the new master link from behind. Still not easy for me. Maybe I just lack fine dexterity though. Also the timing marks on the crank sprockets range from faint to non-existent sometimes, but getting the crank to TDC isn't tough. The cam sprocket markings are always easy to read. When replacing the timing cover gasket, don't forget those little paper gasket 'donuts' that go on the upper studs to space the cover off the crankcase the same amount as the gasket below. Without these you'll get leaks out of the main timing cover gasket.


    The 'Bum has a (long) write up on all of it:

    http://bmwmotorcycletech.info/timingchain.htm
    #2
  3. Sniper X

    Sniper X De Oppresso Liber

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    Looks like I'll need a puller for the Alternator as well, but is there a special puller I need for the cam sprocket?
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  4. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    Any two or three jaw puller of the right size can be made to work, but again be sure to protect the nose of the crank with something soft so it doesn't get messed up. A little flat piece of wood or plastic works.

    You'll need one of these for your alternator rotor:

    [​IMG]


    ...and something like this or similar for the nose bearing and the sprocket. Heat the bearing and sprocket with a propane torch or heat gun before pulling them:

    [​IMG]
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  5. supershaft

    supershaft because I can

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    EASY? I suggest you change your attitude from 'easy' to 'easy to F something up'. I suspect you will have less chance of actually F'ing something up! :D I really think the airhead 'anybody can fix them' mentality whatever you really want to call it should be changed to 'anybody can really F up an airhead'. I have been seeing a lot of butchered birds lately!
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  6. Sniper X

    Sniper X De Oppresso Liber

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    Well, some can do and some can't I guess. I have been working on cars and motorcycles since 1970 so have a fair idea of how to proceed with care.
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  7. disston

    disston ShadeTreeExpert

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    The cam sprocket doesn't usually get changed. It runs in a lot of oil they say is why it doesn't wear as fast as the crank sprocket. If that is so then the crank sprocket also has a lot of oil. But the crank sprocket does wear. Change the crank sprocket and the bearing on the end of the crank in front of it.

    A heavy puller should be used. I think one rated at 10 tons would be the minimum. Some gears come off easier than others. I use a propane torch to heat the gear. Heat helps.

    The tip of the pressure screw is normally pointed and people use this to center it in the hole at the tip of the crank, It fits very well. This is not right. There needs to be a bearing in between the pressure screw and the crank tip. Then it gets confusing by calling it a "bearing". It is not a ball bearing or a roller bearing but something is placed in between the crank tip and the pressure screw. They are sometimes called step plates, really for another application but this will work, and sometimes called buttons. The pressure screw will chew up the crank tip if a button or bearing is not used. A soft material like wood or plastic is not the correct accessory for this tool. Some pullers come with tips that can be changed. They might fit into a hollow of the pressure screw or they might fit over the pointy tip. When great pressure is applied this will allow the tip to turn and not grind away the tip of the crank.

    A Shade Tree mechanics trick from years ago. If needing a puller button and none are available use a socket of the type that is part of a socket set. Any size that fits, that goes over the end of the pressure screw. The pointy tip or flat tip of the pressure screw should fit the bottom of the socket, either 3/8 or 1/2 inch drive. This will work as a bearing.
    #7
  8. supershaft

    supershaft because I can

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    :clap
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  9. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    The crank sprocket wears faster because it's a smaller sprocket. Smaller radius = shorter moment arm = higher face pressure on the teeth = more wear
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  10. supershaft

    supershaft because I can

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    Don't forget that it sees the chain twice as much!
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  11. coastranger

    coastranger Been here awhile

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    so I wonder if it really matters from which direction the master link goes into the chain.. When I did mine 3 years ago I wondered if it was original, as the link went in from the front and the clip went in from the back or inner side. When I put it back together with new chain,I installed it the more common way, the master link from the inner/back side.


    recently somone posted a neat trick with a spring under "tips and tricks" to install the master link.
    #11
  12. Sniper X

    Sniper X De Oppresso Liber

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    The bike doesn't have that much mileage on it and this sound might not be the cam chain but I'll check this weekend. It only happens after the bike is hot and at idle and it isn't bad as in you can't "feel it". You can hear it but it doesn't sound like anything is going to fly apart. It is also something I have heard on many post 70s Airheads that no one says anything about. Last time I head it was a ride on a buddies /7.
    #12