R100GS _ PD - hard to start - then runs well?

Discussion in 'Old's Cool' started by Steve_Col, Mar 9, 2011.

  1. Steve_Col

    Steve_Col Adventurer

    Joined:
    Mar 1, 2011
    Oddometer:
    13
    I bought a R100 GS - Paris Dakar (1994) 2 months ago
    Runs good. - Am real happy

    However - just laterly: when cold it has become hard to start.
    Ambient temperature around 10 - 18 degrees Celsius.

    I giver her choke NO throttle - she turns over - immediately sounds as if it wants to start - firing (has spark). but does not start. I churn that crank - electric start over and over. I cannot help myself "tweaking the throttle" just a touch.

    Eventually she fires up on one cylinder : rattles and rolls this way for 2/3 seconds + then the other cylinder kicks in - = away she goes Sweet As!
    Never any trouble to start when warm / hot.

    Unsure if it be the same cylinder she starts on.

    I found on the forum : http://www.largiader.com/tech/carbs/

    " ...starting routine consists of three crucial steps.

    1. I open the fuel petcocks
    2. I turn the choke.
    3. I push the starter button.
    The engine starts immediately and as it starts to speed up I reduce the choke*, or I ride off and turn it off after a half mile.
    Actually there was really a Step Zero that is more important than these: I cleaned the carbs. And when I say "cleaned" I don't mean that I sprayed some GumOut into the carb intakes; I really cleaned them. I used my Really Nasty Cleaning Stuff and made sure that every trace of fuel residue or corrosion was gone and that the carbs were truly in new condition. Clean carbs won't solve all problems worldwide, but they go a long way towards making the bikes run well.



    Hmmm any suggestion(s)



    I did give her new sparking plugs.


    Ought I "clean the carbs?"


    .

    thnx

    .

    Attached Files:

    • bike.jpg
      bike.jpg
      File size:
      185.9 KB
      Views:
      849
    #1
  2. itsforrest

    itsforrest Ugly bag of mostly water

    Joined:
    May 23, 2008
    Oddometer:
    330
    Location:
    Cardboard box by the beach
    You will likely get more airhead wisdom in the Old's Cool forum. This is forum for the new parallel twins, which are completely different animals.

    Nice looking PD though.
    #2
  3. Steve_Col

    Steve_Col Adventurer

    Joined:
    Mar 1, 2011
    Oddometer:
    13
    can a moderator transfer the post for me ?
    #3
  4. GB

    GB . Administrator

    Joined:
    Aug 16, 2002
    Oddometer:
    57,519
    Location:
    Toronto
    Moved to Old's Cool.
    #4
  5. CanteenBoy

    CanteenBoy Slammin' the ol' Jammer

    Joined:
    Aug 16, 2007
    Oddometer:
    178
    Location:
    NC
    I had the same issue...check your valves. I let mine go too long and had hard starting, rough idle, loss of power etc...
    Adjusted the valves and now it's like a different bike. Just remember, airheads tend to be cold blooded and even properly tuned up are not the easiest things to start in cold (or even cool) weather. Good luck!
    #5
  6. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    Everything else being right, it is a classic example of the jet needle clip grooves being worn out. They will wear from four to three, then two, then one 10mm long groove.

    It could be something you did while you cleaned them. Choke in backwards or wrong side? Choke cables? Mixture screw adjustments and throttle cables? It could be about anything. Good luck!
    #6
  7. ridewv

    ridewv Been here awhile

    Joined:
    Apr 27, 2005
    Oddometer:
    496
    Location:
    West Virginia
    Steve, like yours, my new 1991 R100GS sometimes started on one cylinder only, then the other cylinder would begin. Dealer mechanics adjusted throttle cables, choke cables, and it started up perfectly so off I went. The bike was kept in a heated garage so it didn't happen often. But starting it outside after it had cooled down, in cold weather is when it did its "start and run on one cylinder" deal. It usually would stall and I'd have to re-start it where it did the same thing again. After a few starts the second cylinder would finally kick in and all was normal..... until the next cold start. I could probably have lived with it but it was under warranty so I wanted it right.
    Took three more trips to the dealer. The last one was in 1992 late in the year when it was cold. I just left it telling them "you won't be able to diagnose it in your shop, you'll have to leave it out in the cold then work on it". The culprit turned out to be a faulty electronic module (ignition module I think). They first replaced it with an "updated" version (identified with different colored marking than the original) and it didn't help. (That particular one turned out to be defective and caused the same problem) Eventually they took one off another bike (that had no cold start issue) and it fired right up with both cylinders. They ordered a second replacement module, which superseded the updated one, and it worked perfectly. It was identified with a third colored marking.
    #7
  8. Grayghost66

    Grayghost66 Been here awhile

    Joined:
    Jul 7, 2010
    Oddometer:
    213
    Location:
    Toronto, Ontario
    Hi Steve,

    I have the SAME bike (I bought new in 1992) so we've been togather for awhile. I will give you my 2 cents worth, as to what I would check. If you could check my post "1992 BMW R100GSPD - Need Help!" regarding the engine pins, and if you could check yours and let me know what you find - I would be HUGELY grateful.

    Onto your problem, and what I would check/eliminate;

    1. Start with FRESH gas. Not stored gas with StaBil or other stabilizing agent in it. Drop the bails on the float bowls and decant the old fuel off.
    2. Make sure the vent hose from the Gas Tank that runs on top of the motor is not pinched.
    3. Pull the air cleaner and examine. Replace if necessary
    4. Set the valves. Rotate the crank (plugs out, put bike in 5th gear, and rotate to TDC and recheck them. Still okay?)
    5. You cleaned the carbs with "nasty stuff". Did you remove the floats first? Have you damaged the floats with the carb cleaner? (Need to ask) Wouldn't hurt to replace the diaphrams and give them a complete cleaning (take them off the bike, order a rebuild kit, and rebuild one carb at a time)
    6. When you have the bike running, assuming you have done the above, take it for a good 10km + ride get it really warm and sync the carbs. I have two fans set up on the driveway when I do this, and don't even shut off the bike, but position the fans one on each cylinder, and check the vacuum from the ports on the bottom of each BING. Many use Mercury Stix (these work just fine). I use an Electronic balancer I bought from the BING Agency that works very nicely. These carbs are extremely sensitive to adjustment at the knurled adjuster/10mm nut on top of each carb. Use one carb as a base line and balance the other carb to it. Blip the throttle a few times and let the idle settle and recheck the balance.
    7. Should have mentioned earlier....check the rubber manifolds from the carbs to the cylinders. Any cracks? Questionable? A leak here can cause issues.
    8. While you are at it, pull the battery ground off the back of the transmission and inspect. Give it a light sand and reinstall it. Make sure it is snug.

    Thats all I can think of right now.....

    Let us know how you make out.
    #8
  9. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    There is a service bulletin about that. I have never seen it play out and I have fixed probably about six or seven bikes having the exact same issues buy replacing the worn out jet needles. I just figured they got it wrong but maybe not. My advise would be to check the jet needles first. It's easy to do and an cheap fix if that is it.
    #9
  10. squiffynimrod

    squiffynimrod maximum shrinkage

    Joined:
    Mar 23, 2010
    Oddometer:
    1,607
    Location:
    Flatskatchewan
    According to Oak the ICU's that were defective had white or pink lettering, the newest and "fixed" version had turquoise lettering.
    #10
  11. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    That's in the service bulletins too. I think it is a bit misleading in that not all white and pink lettered ICU's are defective UNLESS you have the later (non crack-0-matic) coil. Then you need a torques ICU for sure. The lower primary resistance of the later coil will lunch the earlier ICU's on a semi regular basis. Bean cans too I believe. It takes 5 or 10k miles but it can happen.
    #11
  12. stickerbush

    stickerbush Adventurer

    Joined:
    Apr 4, 2006
    Oddometer:
    45
    Location:
    Pacific Northwest USA
    Before you go into diagnosis mode try cracking the throttle a bit before pushing the start button. Makes a world of difference doing this with my G/S, only took me about 3 years to figure this out.
    #12
  13. 4ad

    4ad ochlacrat

    Joined:
    Oct 13, 2009
    Oddometer:
    2,806
    Location:
    mid atlantic...no, not the ocean
    You should let the carbs "soak" for a minute or so after turning the petcocks on before hitting the starter...seems to help.
    #13
  14. Steve_Col

    Steve_Col Adventurer

    Joined:
    Mar 1, 2011
    Oddometer:
    13
    Sadly I am back at work - 12 hour days
    At least I will be able to afford some Lovin' for this sweet machine

    I will get back to yo'all...

    Reminds me of an 860 Ducati I owned in the late 70's. (no electric start)

    In my 1st months riding her to work - I would get out in the morning 20 mins before I needed to leave.... and kick kick kick kick "Cough" kick kick Kick KICK "COUGH! kick ... and kick kick kick kick "Cough" kick... and kick kick kick kick "Cough" kick... and kick kick kick kick "Cough" kick

    (Yu get the sad Idea)

    Eventually she'd burst into life with the most joyous sound mechanically ever made.

    One day - after another long, tiring tedious session of :

    kick kick kick "Cough" kick kick Kick KICK "COUGH! kick ... and kick kick kick kick "Cough" kick... and kick kick kick kick "Cough" kick...

    an old man appeared in my yard. He politely noted that he'd heard the trouble I'd been having over the past weeks. He said he'd owned a similiar Duke for some years and asked "did I want him to show me how to start it?"


    DId Nit I!

    He said " Do this same process every time"
    (Never vary the routine)

    1. Swish tank & check for sound of fuel
    2. place on centre stand.

    3. check kill switch - ON
    2. Check petrol cocks - ON
    4. turn ignition ON - check for ignition light

    5. Stand on right hand side of bike
    - use right foot to find Top dead-centre :
    then add 1/4 of a turn of that crank

    6. Use choke if motor 'cold' - NO choke if motor 'hot'
    (do not attempt any 'luke-warm' starts)
    6. Twist throttle grip once - ONE QUARTER turn only.

    then

    Jump on that kick start and she will fire on up!

    each time - every time.

    I loved that machine from that day onward.

    .
    #14
  15. The Raven

    The Raven Banned

    Joined:
    Mar 19, 2006
    Oddometer:
    4,811
    Location:
    Off the map,
    Thats about how I kick start the g/s...minus the kicking...more of a forceful push. A kick would bend the shaft.
    #15
  16. zbg8000

    zbg8000 needs more loctite

    Joined:
    Feb 24, 2011
    Oddometer:
    44
    Location:
    PDX, OR
    You just described my srx600 startup routine!
    If I miss it in the first 3 kicks it's ten minutes of frustration.
    #16
  17. Stagehand

    Stagehand Imperfectionist

    Joined:
    Oct 6, 2004
    Oddometer:
    27,374
    Location:
    Shawangunks
    mine runs cold blooded at first, kinda always has, sometimes a little better, mostly the same.
    #17
  18. Steve_Col

    Steve_Col Adventurer

    Joined:
    Mar 1, 2011
    Oddometer:
    13
    Difficult to start? So I did a couple things:

    1. Took a screwdriver to the black hoses leading to & from the carby:
    they were all loose As : at least 2 turns each before tight - and a couple with 3 or 4 turns before tight.

    2. I took the fuel bowls off both carburettors. Neither seemed to have much "crud" in 'em (if any) .

    I noticed an oddity. The carby on the starboard side did not leak any fuel when both the bowl was off AND the fuel tap was in the "off" position.

    However, the carburettor on the port side leaked like the proverbial sieve with the bowl off, even tho I had the fuel tap also 'off'. Didn na make any difference which'n way I turned that tap: fuel still poured out down thru the throat of the carburettor. WHat did make that flow stop was me manually lifting the bowl all the way "up" with my dinger.

    see photos attached.

    Any suggestions?

    The bike / exhaust was "COLD"

    (how do I add more'n "one" photo to a post?)

    .

    Attached Files:

    • 020.jpg
      020.jpg
      File size:
      191 KB
      Views:
      201
    #18
  19. Steve_Col

    Steve_Col Adventurer

    Joined:
    Mar 1, 2011
    Oddometer:
    13
    .
    here is my finger stopping the flow from the carby

    .

    Attached Files:

    • 021.jpg
      021.jpg
      File size:
      121.7 KB
      Views:
      201
    #19
  20. Steve_Col

    Steve_Col Adventurer

    Joined:
    Mar 1, 2011
    Oddometer:
    13
    .

    here is the flow with out finger stopping

    .

    Attached Files:

    • 022.jpg
      022.jpg
      File size:
      115.8 KB
      Views:
      201
    #20