1971 r50/5 sat for a decade - re starting

Discussion in 'Airheads' started by madtownadv, Aug 13, 2021.

  1. WooPig

    WooPig Redundant Supporter

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    That’s a pretty bike that will make a good project for someone. But the crust in the tank and on the carburetor is a sign that it needs some attention before it runs again.
    Tell them to sell it like it is. They’ll probably pocket just as much and the new owner will be glad to get it.
    #21
  2. madtownadv

    madtownadv Adventurer

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    Bike ownership - motivation.

    This is not my motorcycle. It is my neighbors. It was given to them by the wife's brother for their wedding present 20 plus years ago. He has since passed. The brother had a passion for motorcycles and the bike has great sentimental value to the wife.

    I have had motorcycles for almost 40 years. I recently sold my bike and this is the first time I haven't had one. I thought it would be 'fun' to work on this one and try and get it running. No one is talking about selling the bike. I am willing to put 'some' effort into it. I am not ready to throw in the towel yet :-)

    I have been watching youtube videos on rusty gas tanks. I am thinking about draining the gas, removing the tank and getting a gallon of 'evaporust' and going from there. Anyone ever used it??

    Other thoughts on the gas tank?

    Thanks again to everyone.......
    #22
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  3. PaulBarton

    PaulBarton Long timer Supporter

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    This sounds like a non-financial rewarding project. I think the masses (myself for sure) believed the neighbor had asked for assistance in an attempt to sell it. Since that is not the case, all previous “concerns” about cost can be disregarded. ;-)

    If you’ve got the time and inclination then this can be a fun (but somewhat costly) endeavor. Sounds like the neighbor(s) will support and appreciate the project and you will certainly gain appreciation for what the opposed twin boxer is all about.

    I’m looking forward to the (re)build report.
    #23
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  4. WooPig

    WooPig Redundant Supporter

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    Go for it. :thumb
    Look into POR-15 tank products, even if it’s just their cleaners.
    #24
  5. Disston

    Disston ShadeTreeExpert Supporter

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    Evaporust has a great rep. Lots of good reports. No personal experience. Por 15 is a good product.I have some. Never used it. Vinegar also works, maybe slower.

    I think you should buy the bike from them. A lot of work for no reward. Might loose interest.
    #25
  6. Disston

    Disston ShadeTreeExpert Supporter

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    BTW.That tank is severely rusted. It may be no good after the rust is removed.
    #26
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  7. madtownadv

    madtownadv Adventurer

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    View attachment 3135138 yes this is a big rabbit hole....we will see how long it is fun :-)

    tank is off, gas removed. Have been running water through it to flush out large rust chuncks. It appears to hold water.

    PXL_20210814_185816534.jpg

    I had two different petcocks. One had a fuel screen the other didn't. The one without seems shot.

    old petcock.jpg

    The one with a screen seems to work. Here is the info about it. Any suggestions where to source these..

    petcock.jpg

    One more of the bike...
    #27
  8. madtownadv

    madtownadv Adventurer

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    bike - day one.jpg
    #28
  9. Plaka

    Plaka Brevis illi vita est

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    That replacement petcock looks like a modern Karcoma. The bike originally came with Everbest petcocks. The Karcoma is rebuildable for cheap, the Everbest were crimped closed (IIRC) and people abandoned them, as did BMW. For riding the right angle Karcomas are the way to go, but not for a concourse restoration.

    Do not make assumptions about anything except rubber. All that is most likely bad. The tank is rusty when it proves itself rusty, not before. 15 years ago gas had less ethanol. I use a Streamlight Stylus Reach flashlight to inspect the inside of tanks, as wlll as cylinder bore, piston crowns and valve lips. Lot cheaper than a borescope.

    very carefully remove the badge from one side of the tank. if the screws seem frozen use your favorite penetrant and plenty of time. then remove the side panel, it is hooked under a tab on the tank at the rear. look at the backside of the panel. the chrome tended to be poor here and if the bike has been stored in a rust inducing environment this will be a sensitive indicator.
    #29
  10. madtownadv

    madtownadv Adventurer

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    Float bowl - removed one, it doesn't look nearly as bad as the gas tank. Here are some photos. Hope the gasket will still be good.....

    carb left (1).jpg carb left (2).jpg
    #30
  11. madtownadv

    madtownadv Adventurer

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    #31
  12. Disston

    Disston ShadeTreeExpert Supporter

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    That's a pretty good price on Karcoma petcocks. I think somebody has them for 1 or 2 dollars less. If you have to find a new tank don't buy petcocks yet. Another tank may come with them.

    Look for rust bubbles in the paint on the bottom seem. Water is heavier than gas and so any water in the tank settled on the bottom. During storage and even use this is the worst place for rust being all the way thru. Do not scrap any bubbles in the paint. The rust and the paint can be all that is sealing the gas inside. Eventually this may have to be dealt with but right now try to just get all the loose rust out. Some cleaning with vinegar will help you see what you have to deal with.

    Carbs look pretty good. Looks like new or newer floats so the PO was doing stuff.

    I'd replace both petcocks for simplicities sake.

    You only need one petcock to start the bike so leave the Everbest one switched to off and use the dirty Karcoma for starting. You can get the Karcoma working with carb cleaner and a spray oil type lube. Hope the screen is usable. That is what should catch any rust flakes.
    #32
  13. Plaka

    Plaka Brevis illi vita est

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    Replace fuel lines of course and fit the small conical filters just upstream of the carbs.

    The carb bowl gaskets are trivial, and cheap. They provide tension on the bowl bail and keep splashing water out. If you buy full rebuild kits for the carbs they may be included.

    Capitol cycle has changed hands some but they are an old standby and should still be brick & mortar.

    The karcoma petcock is rebuildable unless the detent washer is worn out. When you move the lever if it clicks into different positions you have a good rebuild candidate. The rebuild is simple for the most part and cheap. There are some things to know however. Bud once commented that he didn't rebuild them because for the cost of his shop time it was cheaper for the customer to replace. When I rebuild my own I do some extra things and they need no more attention for as long as I own them, unlike a factory new one.

    You can start the bike with no petcocks or tank. A service bottle hung overhead that has a valve is used for this. Amazon. These are handy when you need to track down something under the tank while running the bike to do it. Can save much time. I had been running saddle tanks so I could run the motor on those.

    What do the bottom of the float bowls look like?

    While you have the camera out, remove a rocker cover and post up a picture of the head underneath.
    #33
  14. Pokie

    Pokie Just plain Pokie.

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    If it was your bike, I'd probably do all kinds of things to keep it good. Seeing as how you are just getting it running for the neighbor, I'd do the minimum to get it running. A drop of oil from an oil pump can will do wonders for any and all external moving parts (yes, even a drop or two of oil into the ignition plunger hole). I'd change the oil but NOT drop the pan. I'd fill the gas tank with vinegar, right to the top and let it sit. After about a week, drain the vinegar, rinse out the tank, strain the vinegar and fill it again. You may have to repeat this a few times, don't be in a hurry.
    #34
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  15. madtownadv

    madtownadv Adventurer

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    Day 2 - soaking tank with 'Evaporust', new battery and changed oil, transmission oil, and final drive oil.....

    evaporust.jpg

    It is only a gallon, so I need to rotate the tank every once in a while. When it is completely upside down it leaks out oof the top filler hole....

    I feel like I will be ready to give starting a try soon. We'll see how busy I am during the week.....
    #35
  16. Disston

    Disston ShadeTreeExpert Supporter

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    The cap seal may leak a little on older bikes but not be a problem once the tank is mounted.
    #36
  17. OldCrustyStuff

    OldCrustyStuff Adventurer

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    That gallon of Evaporust will make a dent but you will exhaust it’s effectiveness long before you finish as badly rusted as that tank is. I use white vinegar for a week-2 weeks because it’s cheap, then I rinse really well with last rinse having some baking soda to neutralize vinegar/acid.

    After all that I use Evaporust to “finish.

    Good luck!!
    #37
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  18. Plaka

    Plaka Brevis illi vita est

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    Why are you derusting the tank on a non-running bike? I like (?) how people tell you the tank is all rusty but none have looked in it or know the first thing about it. We don't even know the mileage on this bike!

    Drain the old gas. Rinse tank with a cup of fresh gas then dump that. Try petcocks and find the one that flows the best, leave the other turned off. Put in a gallon of fresh gas. Replace fuel lines (safety) and fit filters (cheap insurance). Drop float bowls and turn on petcock to make sure gas is reaching both carbs. Tip bike to side with the working petcock to get the gas there if nothing at first. Now you got gas.

    Open airbox and inspect. Leaving filter out for the moment is fine. Now you got air..

    Drain oil and fill with something cheap. Generic 10-40, strait 30, whatever but you do want a detergent oil. This stuff is not suitable for running but fine for a brief flush. Replace filter. A cheapo aftermarket one is fine, but again not for going anywhere. reuse the gasket on the drain plug, carefully. It will leak, who cares, put a pan under it and keep your eye on the ball. Kick bike a bunch to move the oil around. Now you got oil pressure.

    Remove battery. Jumper it of your Pinto and test for sparks. If none dive into that and fix. Now you have sparks.

    Kick it a few more times with the ignition on. Get the oil light to go out. Now try starting it. If you can get some chuffs it'll run. if you get lucky it'll run badly.

    This is a days worth of work and about $20 expense.

    -------------------------------------------------------------

    Your objective was to get the bike running but you are doing every thing but. You can get endless babble around here (and some good info) but people get into it to amuse themselves, not to meet your objective: get the bike running. The bike may be a good candidate to put back on the road, or it may not be. The owners motives are also completely unclear. Emotionally attached to it? She can be attached to it and just leave it sitting where it has been. There is no one to ride it. I can see you being asked to shine it up and look nice before it goes back in the garage. But make it running and roadworthy so it can sit and rot another 10 years? Something smells wrong all around with this deal (no offense intended)
    #38
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  19. madtownadv

    madtownadv Adventurer

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    This is a great post, very pragmatic. I spent $150 so far. Battery, petcock, motor oil, transmission and final drive oil, some fuel line and the evaporust. I plan on letting the tank soak with the evaporust for a couple days and try and start it. My neighbor will pay me back. i have had a good time doing the work and learning as I go. I have never had a BMW cycle before. Looking forward to getting the petcock (ordered online) putting some fresh gas in it and giving it a try....
    #39
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  20. Disston

    Disston ShadeTreeExpert Supporter

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    You're doing great. I think you said in the Old's Cool post that you have owned motorcycles but don't really consider yourself much of a mechanic? Or something like that. Airheads are where many of our riders have discovered the joys of fixing it themselves. We recommend riders do as much of the required maintenance as these machines can require and many of us like working on the bikes even more than riding.

    Yes we get awfully wordy sometimes but the owner gets to pick their own path.

    You're about to discover a new interest in life.
    #40