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Thread: How bad can I screw it up?

  1. #1
    Registered User wasserwolf's Avatar
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    How bad can I screw it up?

    Hey guys.

    I am new to the org. I bought a 1976 R60/6 two years ago and after a lot of work (new 1 over pistons, heads redone, carbs rebuilt and Elec gremlins resolved) she runs great. I did most of the work but took it to a master mechanic to resolve the electrical after 3 frustrating months trying myself. It was worth getting it running. The one thing that is a little annoying is stalling upon rapid deceleration. She runs so sweet at speed and it took so much changing parts and bloody knuckles to get here that I am paranoid about fiddling with the carb settings. I must have post tramatic resto disorder and have a fear I will botch it to the point where it results in a cascade failure. How often do you guys fiddle with carb adjustments? Every week? Once a season? Thanks for any comments.WasserWolfin Milford.jpg

  2. #2
    Liaison 20774's Avatar
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    Welcome to the forum! Interesting custom windscreen...protection but that sleeker look!!

    You're bike should have the slide carbs on them. I suspect that any "whack it open" response on these types of carbs could result in the symptoms that you're describing. For a brief moment, you've introduced a lot of air and the gas hasn't had a chance to catch up. So, first...don't do that! BTW...the CV carbs that are on the bigger model bikes have a bit of dampening effect in them...on those bikes, the throttle isn't hooked directly to a slide but rather to a butterfly downstream of the carb. The CV carbs operate on vacuum, so whacking the throttle (and the butterfly) has a bit of delay until the vacuum can raise the slide. During the delay, the air/fuel mixture richens a bit because more air is being demanded but the slide hasn't risen, so the air is moving faster while sucking up a bit more gas.

    Seriously, though, working on the carbs is not take difficult. The idea would be to work on one at a time and take notes of what you're doing. Usually once carbs are working the way you want them, they don't require that much attention. But if you begin to notice a drop off in mileage and performance, it might be worth investigation.

    Once thing you could try is to richen the idle circuit. There is a screw on the side of the carb that controls an air screw...so turning the screw CW or inwards a bit will cut off air, thus making it richer. You could try moving that screw the same on both carbs maybe an 1/8 or 1/4 turn and see what happens.

    In the end, you might need to perform a synchronization between the two carbs so they work together and hopefully give better performance.
    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 PAS's Avatar
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    Make sure the valves are adjusted and heads re torqued first!

  4. #4
    Registered User wasserwolf's Avatar
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    Thanks for the response. I see the stall on deceleration so I could be "wacking it closed". Would this still produce the same imbalance in air/fuel? I will slow down my throttle control to see the effect. Before I did all the engine work, I played with the carb setting and balancing like they were violins in the symphony because I thought that was the problem. In the end is was the coils dumping out due to corroded wiring. I guess I need to play with them a bit at a time and see what I can do. Valves and heads have been verified adjusted and torqued properly. Thanks.

  5. #5
    Liaison 20774's Avatar
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    Sorry...missed the decel part. In that case, I'm wondering if an issue might be the float levels and the fuel in the float bowl...could be the fuel is shifting around when the front end dives.

    Couldn't hurt to try a change in the air screw...just be ready to move it back if you don't find any change.
    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!

  6. #6

    Check the advance wieghts & springs

    Make sure the advance unit on the end of the cam shaft is doing its job properly. Maybe get in there, clean, lube and install new springs might be a better idea than messing with the carbs just yet. You could always slap a timing light on it and do a basic check to see if the advance is working and working smoothly.

  7. #7
    Registered User wasserwolf's Avatar
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    Quote Originally Posted by 69zeff65 View Post
    Make sure the advance unit on the end of the cam shaft is doing its job properly. Maybe get in there, clean, lube and install new springs might be a better idea than messing with the carbs just yet. You could always slap a timing light on it and do a basic check to see if the advance is working and working smoothly.
    Have has this off but not really examined the weights. I will take a look. I have used the timing light and correct letter in the window verified using Clymer manual.


    Also in response to the custom wind screen, I do like it a lot better than the taller original one. It lets some air flow, still gives good protection and looks 10x better. A shop near me (Soltis Plastics in Waterford MI on M-59 ) has templates and the expertise to modify or make new.

  8. #8
    Quote Originally Posted by wasserwolf View Post
    Have has this off but not really examined the weights. I will take a look. I have used the timing light and correct letter in the window verified using Clymer manual.


    Also in response to the custom wind screen, I do like it a lot better than the taller original one. It lets some air flow, still gives good protection and looks 10x better. A shop near me (Soltis Plastics in Waterford MI on M-59 ) has templates and the expertise to modify or make new.
    Also, one can purchase "Lexan" and do it yourself for the windshield at McMaster-Carr
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

  9. #9

    Aftermarket mufflers?

    Took a look at the picture again and noticed you have aftermarket mufflers on it. This may have an effect on the carburetor tune so if your advance weights & springs check out good you may have to dig into the carbs a little. Suggest maybe you start with the needle position after you check to make sure you accelerator spring & ball work as they should to. I saved an R 60/6 from certain death a year or two ago and got it running with just a few basic steps, it stumbled a little so I went back into the carbs and found the accelerator circuit was gummed up on the left carb. Its a little pricey to replace the stuff so I did a little shade tree rehab and it runs like a swiss watch now.

  10. #10
    #4869 DennisDarrow's Avatar
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    Welcome aboard......

    You have the last of the "old fashioned" engines that served BMW so well for a very long time. Then the increased the CC's and had to tune accordingly. Anyway, the "old" way to tune the carbs is to yes, clean them the best you can first. I assume you have done that already. At least taking out the various air screws and such, carb cleanering them and blowing them out......Yes, setting those floats is totally important..............Get all of that done first and do it right. Then.........

    ohhh the heresy.......
    Pull a plug wire, yes, ground it, then go to the other side and adjust the idle screw so it just chugs nice, now.....adjust the air screw in and out until it runs the best. Now, set the idle screw down where it just barely chugs. Adjust the air screw again. Now.....Almost finished. Set the idle down so that when you pull the other pug wire, the idle will chug along for maybe 4 or 5 times and then die..............Do the same to the other side. You now have synced carbs and have them adjusted where they will idle the best........

    MAKE SURE YOU HAVE HUGE......HUGE.....FANS RUNNING IN FRONT OF THE CYLINDERS WHILE YOU DO THIS. Or, do these adjustments over like 10 minute times, ride it a bit to cool it down and then do it again...............Oh yes, before you begin adjusting, ride the thing for 10 miles or so to make sure it is warmed up.........God bless....Dennis

  11. #11
    Registered User wasserwolf's Avatar
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    Thanks Dennis

  12. #12
    Liaison 20774's Avatar
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    Pull a plug wire, yes, ground it,
    I'm sure Dennis is aware, but pulling the plug wire is really a no-no...what Dennis is referring to regarding grounding is important, but at no time should the plug be ungrounded. The best way to do this is to fashion an extension for the metal tip of the spark plug that is about 2-3 inches long. I've done this with a some threaded rod and the small screw-on adapters that come with the plugs...see the picture. When this is put on the end of the plug and the plug cap is positioned back onto the opposite end of the rod, you know have a convenient way to ground the spark energy. You do this by using a long plastic handled screwdriver, touch the tip to the engine fins, and then bring the shaft of the screwdriver onto the spark extension rod. Do this swiftly and hold it against the rod firmly, you have provided a solid path for the spark energy to flow to ground. This protects any reflections of the energy back into the coils where it can do damage...maybe not that is seen now, but could show up down the road.

    Here was a previous thread:

    http://forums.bmwmoa.org/showthread....horting-Method
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    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!

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