Service-New to Me-'81 R100/t

Discussion in 'Airheads' started by brittrunyon, Apr 6, 2013.

  1. brittrunyon

    brittrunyon R 100 GS F 650 GS

    Joined:
    Oct 6, 2010
    Oddometer:
    645
    Location:
    The High Desert of New Mexico
    I know how you guys like pictures :D

    [​IMG]

    So here's the skinny.
    1981 R100/t was bought (not by me) in Germany and then sometime later shipped to the USA.
    This bike has had 2 owners in it's 32 years of existence.
    The original owner sold it 2 years ago after it sat for awhile.
    ............from 2001 to 2013 only 3,500 miles were clocked (so it didn't actually sit the entire time)
    ............the 2nd owner had it for 2 years and clocked maybe 1,500 miles of those miles.

    Here's what I know:
    1. Mileage is 143,000 miles
    2. Oct. 1991, 63,000 miles, front wheel replaced due to recall (not rear wheel).
    3. Aug. 1995, 98,000 miles, new rings and valves.
    4. June 1997, 111,000 miles, new cylinders, pistons and rings.
    5. Oct. 2001, 139,000 miles, new valves, valve guides

    Here's what I have for 32 years of records........
    The original book with 4 years of maintenance.........

    <a href="http://s1089.photobucket.com/user/brittrunyon/media/1981%20R100%20t/_DSC8539_zpsdf542fa9.jpg.html" target="_blank"><img src="http://i1089.photobucket.com/albums/i358/brittrunyon/1981%20R100%20t/_DSC8539_zpsdf542fa9.jpg" border="0" alt=" photo _DSC8539_zpsdf542fa9.jpg"/></a>

    Then the original owners records up until 2001 & then just stop.
    .............It appears that the original owner was very good with maintenance, oils, bearings, lubes, etc.
    .............There is nothing known from 2001 to present time.
    .............There is nothing in the records of any other parts being replaced, other than the ones listed above.
    .............Could this be true?

    [​IMG]

    There is no records from 2001 to the present.
    The 2nd owner stated that he changed all the fluids prior to my taking possession of the bike.
    Rumor from the 2nd owner is that the carbs were rebuilt at 70,000 miles (by original owner).

    The bike as I see it:
    1. There are no oil leaks.
    2. It is all "original (?)" OEM parts.
    3. Needs a rear tire.
    4. The inside of the tank looks great.
    5. The starter looks original, could this be true?
    6. Plug wires & coils look original, could this be true?
    7. There's a slight "clunck" in the head light area when hitting a bump at speed (the steering head bearing test OK).
    8. Needs rear brake shoes.
    9. Front brakes OK.

    What I've done so far (all in this order):
    1. Disassemble and clean ignition trigger unit (bean can)-(the idle was sticking at 2,500rpm's)
    2. Adjusted valves (.004 In & .008 Ex)
    3. Set the timing (more on this in a minute)
    4. Syn the carbs with shortening method.
    5. Cleaned & lubed all electrical connections. (this helped performance a lot)
    6. Removed Pulse Air System.
    7. Rode it 350 miles with Seafoam additive in fuel.
    8. Replaced throttle cables (they needed replacing).
    9. New air filter.
    10. New inline fuel filters.
    11. 2 new sections of fuel line.

    What I'm feeling in the seat of my pants:
    1. The power is not what it should be.
    2. I wonder about the condition of the carbs.
    3. I wonder if the plug wires, coils, etc are not functioning as they should be.

    So now what?
    First I intend to revisit the timing.
    There's sometimes a "stubble" on light acceleration at 1,200-1,500 rpm's.
    The Original Manual states:
    ..........."ignition timing: 6 degrees before TDC = "S" mark on flywheel".
    When I did the timing the "S" mark was below the center line but I could not advance because the bean can was at max counter clockwise rotation, as seen in image below.

    (sorry, piss poor photo)
    [​IMG]

    Any ideas on this timing problem?

    So Now........................:ear
    #1
  2. Solo Lobo

    Solo Lobo airhead or nothing

    Joined:
    Mar 16, 2004
    Oddometer:
    9,694
    Location:
    Shoreline, WA
    Stretched timing chain?
    #2
  3. Airhead Wrangler

    Airhead Wrangler Long timer

    Joined:
    Mar 4, 2008
    Oddometer:
    6,833
    Location:
    Back in Seattle, FINALLY
    Or timing chain installed one tooth out maybe?
    #3
  4. Kt-88

    Kt-88 I like everything.

    Joined:
    Sep 9, 2012
    Oddometer:
    1,017
    Location:
    SLC area, Utah
    That's what I was thinking.
    #4
  5. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    Part of the trouble could be the bean can itself. Time to the F mark and see were it goes at idle. They very often do not time both marks at the same time. If that's the case, bend the advance weight tabs so that it will. Very easy to do through the can's inspection port. It doesn't take very much.
    #5
  6. halflive

    halflive Been here awhile

    Joined:
    Apr 14, 2009
    Oddometer:
    399
    Your front fender looks awkward, is it mounted the wrong way round?
    #6
  7. Bill Harris

    Bill Harris Confirmed Curmudgeon

    Joined:
    Sep 20, 2008
    Oddometer:
    9,746
    Location:
    backwoods Alabama
    What does the F or Z ignition timing mark do at >3000 rpm with the current setting ? It should be centered in the window at that RPM. THAT is the important timing setting, not the Idle "S" setting.

    --Bill
    #7
  8. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    They both are important if you want it to run right.
    #8
  9. brittrunyon

    brittrunyon R 100 GS F 650 GS

    Joined:
    Oct 6, 2010
    Oddometer:
    645
    Location:
    The High Desert of New Mexico
    Wow.......
    Your right it looks backwards, especially with that silly mud flap :huh

    More on the timing a little later...............
    #9
  10. brittrunyon

    brittrunyon R 100 GS F 650 GS

    Joined:
    Oct 6, 2010
    Oddometer:
    645
    Location:
    The High Desert of New Mexico
    After revisiting the timing.....
    ...........there is no F mark
    ..........not ready to bend any tabs in the bean can just yet

    At 1000 rpm's the OT & S marks are below the window
    .................(the OT mark is above the S mark on the same tab, on the fly wheel)
    .................the OT mark can be seen at the bottom of the window but the S mark is out of sight
    .................the bean can is advanced (counter clockwise) as far as possible

    At 3000rpm's there is "nothing" showing steady in the window

    There's no Z mark showing anywhere between 1000 to 4000 rpms.

    It rides just OK, doesn't rattle, but as I stated earlier it's a gutless beast which I attribute to old electronics.......maybe?
    #10
  11. Plaka

    Plaka Brevis illi vita est

    Joined:
    Jun 19, 2010
    Oddometer:
    4,625
    Electronics ain't like bread. The work or they don't.

    Coils might be weak and/or wires bad. Check your sparks (carefully, run a HT lead open and you trash the ignition immediately)

    Timing could be way off. So resolve that.

    Check compression.

    If a valve job only lasted 41k miles something is very wrong. possible with the person doing that work. And why were the jugs replaced?

    You don't have to take the bean can apart to service the advance weights. You do it through the service window. Did you return the can to the same place on the block where it was when you took it off?

    How did you balance the carbs by the shorting method? If it's smooth you're likely good there but do some plug chops to check mixture.
    #11
  12. brittrunyon

    brittrunyon R 100 GS F 650 GS

    Joined:
    Oct 6, 2010
    Oddometer:
    645
    Location:
    The High Desert of New Mexico

    For sure, you can't put peanut butter on electronics, but I think corrosion like peanut butter can restrict the spark. :D

    I agree timing is first.

    The valves & valve guides were done 4,000 miles ago, as stated above, not 41,000 miles, that was the first time.
    I have no idea why the cylinders were replaced.

    I did return the can back to it's original location.
    What is the service routine for the advance weights through the window?
    What lube should be used?

    I balanced the carbs the way I always have but according to you on another thread I did it wrong, so I'm still waiting for an update on the proper procedure.
    Is plug chops like pork chops?:D

    So there's no Z mark in the window.
    What's up with that?

    Thanks for your input.
    #12
  13. Plaka

    Plaka Brevis illi vita est

    Joined:
    Jun 19, 2010
    Oddometer:
    4,625
    You can use peanut butter but toothpaste works much better. Real heatsink paste is the class act and washes off well. This is for soldering, you use a very different type of heatsink paste under the ignition module and it should be renewed annually.


    Remove corrosion from all connections. Air eraser running baking soda.
    I meant how long that first valve job lasted.

    Open window and discard cap. Turn unit so pivot is in window, squirt of brake cleaner with window facing down so it drains. You want to get the pivots only as best possible. it's all plastic bushings in there, I would use a silicone grease on the backer plate and silicone oil on the pivots. I used the first thing I grabbed which was Mobile 1 synthetic grease. Close the window with aluminum foil tape
    http://www.eskimo.com/~newowl/setting_airhead_CV_carbs.html

    No.
    Somebody moved the window? Walk the flywheel around by hand and clean +paint all the marks. Whiteout works OK and comes in a bottle with a handy brush. Paint on, dry, scrub off. Brake cleaner prep and go light, you have a clutch disk in there.
    #13
  14. brittrunyon

    brittrunyon R 100 GS F 650 GS

    Joined:
    Oct 6, 2010
    Oddometer:
    645
    Location:
    The High Desert of New Mexico
    Well Okie Dokie here's where I sit:

    At 3000 rpm's the Z mark is just below the window, it wasn't that it isn't visible, I just needed to look down, almost out of sight.
    ........almost steady but not quite

    So there it is:
    ........The OT & S marks are below the window at 1000rpms
    ........The Z mark is below the window at 3000rpms
    ........& I can't advance the the can.

    I serviced the bean can last week, it was not that dirty, & lubed with silicone grease/oil.

    gotta luv photos

    <a href="http://s1089.photobucket.com/user/brittrunyon/media/1981%20R100%20t/_DSC8417_zpsc3e2e242.jpg.html" target="_blank"><img src="http://i1089.photobucket.com/albums/i358/brittrunyon/1981%20R100%20t/_DSC8417_zpsc3e2e242.jpg" border="0" alt="Bean Can photo _DSC8417_zpsc3e2e242.jpg"/></a>
    <a href="http://s1089.photobucket.com/user/brittrunyon/media/1981%20R100%20t/_DSC8424_zpsbee166b8.jpg.html" target="_blank"><img src="http://i1089.photobucket.com/albums/i358/brittrunyon/1981%20R100%20t/_DSC8424_zpsbee166b8.jpg" border="0" alt="Bean Can photo _DSC8424_zpsbee166b8.jpg"/></a>
    <a href="http://s1089.photobucket.com/user/brittrunyon/media/1981%20R100%20t/_DSC8426_zpsa2c32edf.jpg.html" target="_blank"><img src="http://i1089.photobucket.com/albums/i358/brittrunyon/1981%20R100%20t/_DSC8426_zpsa2c32edf.jpg" border="0" alt="Bean can photo _DSC8426_zpsa2c32edf.jpg"/></a>

    I'll try a little more silicone lube through the widow, every thing in there is now clean.

    Thanks so much for the Carb Balancing Link!
    #14
  15. kaput13

    kaput13 gasoholic

    Joined:
    Nov 20, 2010
    Oddometer:
    668
    Location:
    South Florida
    Brittrunyon,

    Your timing issues could be due to any one of the issues cited by others above but I can tell you that I experienced the exact same timing symptoms "bean can advanced as far as possible" that you describe. The fix in my case was switching out the bean can for one that was in known working condition. Problem was resolved (eventually switched out for a Motorrad Elektrik Alpha System). Know of two other occasions where this same bean can related issue has occured. I'm hoping that you can fix the bean can :evil so I can copy your efforts with my spare.
    #15
  16. brittrunyon

    brittrunyon R 100 GS F 650 GS

    Joined:
    Oct 6, 2010
    Oddometer:
    645
    Location:
    The High Desert of New Mexico
    You means this?

    [​IMG]

    Here's the OT mark at 1000 rpms

    [​IMG]
    #16
  17. brittrunyon

    brittrunyon R 100 GS F 650 GS

    Joined:
    Oct 6, 2010
    Oddometer:
    645
    Location:
    The High Desert of New Mexico
    Kaput13,
    Thanks for the heads up on your similar issue.
    I'm wondering at this point what should/could be done to the bean can to solve the problem. :scratch
    #17
  18. kaput13

    kaput13 gasoholic

    Joined:
    Nov 20, 2010
    Oddometer:
    668
    Location:
    South Florida

    Exactly.
    #18
  19. kaput13

    kaput13 gasoholic

    Joined:
    Nov 20, 2010
    Oddometer:
    668
    Location:
    South Florida

    This I do not know other than to say that I've seen a post somewhere of someone rebuilding a beancan (with pictures) should you be so inclined. Maybe someone in the know will provide a link. If it turns out that the beancan is at fault there are people out there rebuilding beancans and if you want to spend more money go for one of the aftermarket options. BMW item is even more. Buying a used one is a crapshoot.
    #19
  20. brittrunyon

    brittrunyon R 100 GS F 650 GS

    Joined:
    Oct 6, 2010
    Oddometer:
    645
    Location:
    The High Desert of New Mexico
    + & - to battery
    clip to right plug wire

    I know about "sight dead down" the window, it's just taking a photo was a little difficult so the angles a little "catee wompus".
    #20