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Thread: R50/2 starting problems

  1. #1

    R50/2 starting problems

    Heres the deal. Got an R50/2, rode it home, about 5 or 6 miles. Seemed to run ok, but after about two weeks of just sitting and cleaning up,will not start. While working, removed Twinmaster saddle bags and turn signals and wiring. It gets spark, although I am not sure if it is too weak. Also replaced gaskets in carburetors. Will not fire at all. Checked points and regapped, and checked all wiring visually. Any ideas would be appreciated. Could the coil have stopped working, and if so how can it be checked?

  2. #2
    Liaison 20774's Avatar
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    Usually a bad coil shows as a problem trying to start when warm, like after a gas stop. Doubt this has changed, but have you checked the saftey gap at the coil? Below the point at which the spark plug wires attached to the terminals on the coil, there are two points which should have about 10mm of gap between the tip and the end of the spark plug wire or terminal. Too close, and the spark will jump acorss the gap rather than the electrode at the plug tip. Something to check

    Another thing might be the magneto timing. Generally, once set, it doesn't change. Note that magneto timing and ignition timing are set independently of each other. The magneto must be timing to provide the hottest spark when you need it the most...when trying to kick start. Vech has an article on the magneto and hard starting:

    http://www.benchmarkworks.com/articl...hardstart.html

    My guess, though, is you haven't figured out the starting routine. The carbs need to be tickled...basically you're flooding the carbs. Each bike will take a different approach. But generally here's what I'd try:

    - turn gas on, ignition off
    - push the tickler down on each carb for a count of 3-5. This is where you'll have to experiment.
    - without touching the throttle, kick the bike over 4-5 times
    - then ignition on, throttle open maybe 1/8 to 1/4, kick the bike
    - if it begins to run, you might need to jab at the ticklers quickly while working the throttle

    Starting hot, provided you don't have a coil problem, may require a different approach. My R69S tends to flood when hot. One thing to remember to do is turn the petcock off about a block from where you plan to stop. That keeps the gas from expanding due to engine heat soak and either dripping on the ground or further flooding the carb. To start hot, I do the following:

    - gas off, key off
    - throttle wide open
    - kick 4-5 times
    - ignition on, kick the bike
    - when it catches, slowly work the throttle and reach down and turn on the gas

    You could also have brass floats that have cracked and are sinking resulting in a severely flooded bike. You can carefully remove the top of the carb and extract the float. If you shake and hear gas, that's the problem. Vech has begun to sell ver 2.0 of his plastic replacement floats...might be time for that.

    A number of other possibilities...see if any of that helps.
    Kurt -- Forum Liaison ---> 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!

  3. #3
    Registered User vechbmw's Avatar
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    Hard start? try this.

    The one thing I have observed after fooling with pre 70 BMW's over the last 35+ years, is that most people want to use the ticklers on the carbs, every time they try and start it. This is not what you should do except as a last resort.

    For some reason, (don't ask me why, but I've learned this the hard way) if you ever gas foul (get them wet) the plugs (from tickling the carbs) you can pull them out, dry them off, put them back in, and it [I]will not start for love nor money.[I] Stick a fresh set of plugs in, and it will start on the first kick!
    Why can't you just clean and reuse them? One of the great mysteries of life.
    I tell people all the time, carry a spare set of plugs if you insist on using the tickers.

    The reasoning behind not using the ticklers or at best VERY sparingly. (the R69S seems to always want a VERY quick 1/2 second blip of the tickers when cold, but not R50-R60's)
    1. basically slide carbs with no accelerator pump are a variable diameter venturi.
    2. The velocity of the air, rushing through the neck down of the venturi creates a vacuum which draws fuel.
    3. You can't kick it as fast as it runs, even at idle. So at kick start speeds, the air velocity is very low. If you OPEN the throttle, you are increasing the diameter of the venturi, and making the velocity is LOWER. It won't draw fuel. It won't start.

    That is why, the starting procedure on an R50 or R60 is to:
    1. have it on the center stand NOT on the side stand
    (having it leaning on the side stand will cause the left carb to FLOOD)
    2. turn the gas on, and count to 5 slowly, 1001, 1002 etc,
    3. shove the key down.
    4. DON'T touch the throttle.
    5. kick it. IF the bike is properly tuned, idle mix is properly set, and it has a good coil - good spark, it will take off an run in a kick or two.
    6. Let it warm up. DON"T touch the throttle, if you do, it will QUIT immediately.

    Install a set of new spark plugs and go try it again.

    Vech
    MOA Ambassador #9462
    Owner, Bench Mark Works

  4. #4
    Quote Originally Posted by vechbmw View Post

    That is why, the starting procedure on an R50 or R60 is to:
    1. have it on the center stand NOT on the side stand
    (having it leaning on the side stand will cause the left carb to FLOOD)
    2. turn the gas on, and count to 5 slowly, 1001, 1002 etc,
    3. shove the key down.
    4. DON'T touch the throttle.
    5. kick it. IF the bike is properly tuned, idle mix is properly set, and it has a good coil - good spark, it will take off an run in a kick or two.
    6. Let it warm up. DON"T touch the throttle, if you do, it will QUIT immediately.

    This is the procedure I use for my /2
    07 R1200R - 75 R90/6 - 67 R50/2 - 75 R90S
    1983 Suzuki GS1100E
    2007 Honda CRF450X

  5. #5
    Registered User
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    "For some reason, (don't ask me why, but I've learned this the hard way) if you ever gas foul (get them wet) the plugs (from tickling the carbs) you can pull them out, dry them off, put them back in, and it [I]will not start for love nor money.[I] Stick a fresh set of plugs in, and it will start on the first kick!
    Why can't you just clean and reuse them? One of the great mysteries of life."
    ======================================

    Absolutely spot on - cleaning rarely works with flooded magneto bike - cleaning and heating over coleman gas stove does not work - running the plug in a /5 for a while will work - finish cleaning with a stiff steel wire brush only sometimes will work - different plugs always work

    Everybody's start routine is different - mine as follows:

    Cold (sat at least overnight 50deg weather):
    Gas on
    Brief Tickle 1-2 sec
    Ignition off
    Kick gently to cause compression stroke each cyl
    Ignition on throttle closed
    One vigorous stroke should start
    If no start or fart try 2 or 3 more strokes
    If no start or fart tickle again
    Ignition off
    repeat sequence
    If fart and not start ignition off for one stroke to clear smoke and recharge fresh mixture

    Warm (started same day and sat no more than 3 hours)
    Gas on
    No tickle
    Ignition off
    stroke to bring each cyl through a compression sequence
    Ignition on throttle closed
    1 stroke will start it

    Hot (started less than 15 minutes ago)
    Gas on
    Ignition on - throttle closed
    1 stroke will start it - took lots of money and beer off HD sporty riders over the years with this bet
    Generally win kick start contests at ABATE events - 18-22 starts in a minute

    DO NOT GET EXCITED OR MAD AND TRY TO STROKE RAPIDLY - you will only wreck
    the kick sector gear

    I taught myself to kick from the saddle in seated positon with heal on pedal so never on centerstand - bad back will not allow me to use center stand unless desperate for repair

    If it has a bad coil but not dead coil 0.015" plug gap will work better than spec

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