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Thread: decelleration

  1. #1

    decelleration

    I recently purchased a 1967 R60/2. The engine does not rev down properly. Sometimes it takes several seconds. I don't have the shop manual yet. Could this just be a sticky cable problem or as I suspect some sort of a spring issue inside carbs? Also, left carb leaks only when bike is off, pet cock on and on the side stand.
    Thoughts? Doug

  2. #2
    Liaison 20774's Avatar
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    Doug -

    Since it's a recent purchase, your have no history on the bike. Can the previous owner help out with that?

    My thoughts are:

    - you can find out if the cable is causing the problem by looking at the intake side of the carbs and see if the slide is all the way down but yet the engine is still revving.

    - could be that the advance unit is sticking with the weights out a bit; the unit would need to be cleaned. When the bike is revving as you say, try letting out the clutch while in gear, but only let it out enough to drag the engine RPM down. Does it stay at the lower RPM? That would be sticking weights. If it climbs again, see my next comment.

    - could be that the carbs need to be synched and that the last time that was done, the bike was not up to operating temperature. When it isn't warmed up, then the settings done while cold don't work for when the engine is warm.

    As for leaking carbs while on the side stand, I would tend to think "they all do that". The float is probably binding because the bike is leaned over. Generally, the petcocks should be off when the bike is not running.

    I would start with a good carb overhaul...it's not that difficult. Do one carb at a time just so you have something to look at while working on the other carb.
    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

    weights

    Quote Originally Posted by 20774 View Post
    Doug -

    Since it's a recent purchase, your have no history on the bike. Can the previous owner help out with that?

    My thoughts are:

    - you can find out if the cable is causing the problem by looking at the intake side of the carbs and see if the slide is all the way down but yet the engine is still revving.

    - could be that the advance unit is sticking with the weights out a bit; the unit would need to be cleaned. When the bike is revving as you say, try letting out the clutch while in gear, but only let it out enough to drag the engine RPM down. Does it stay at the lower RPM? That would be sticking weights. If it climbs again, see my next comment.

    - could be that the carbs need to be synched and that the last time that was done, the bike was not up to operating temperature. When it isn't warmed up, then the settings done while cold don't work for when the engine is warm.

    As for leaking carbs while on the side stand, I would tend to think "they all do that". The float is probably binding because the bike is leaned over. Generally, the petcocks should be off when the bike is not running.

    I would start with a good carb overhaul...it's not that difficult. Do one carb at a time just so you have something to look at while working on the other carb.
    It has a tendency to return to idle with your suggestion of letting the clutch out while in first gear. Are these weights behind the front engine cover and can be cleaned in place with a good parts loosener as in Blaster. I have Marvel Mystery Oil and have had good luck putting it in the fuel to lubricate the slide on a 1967 Triumph TR6C carburetor. So, I don't see any problem trying a capful of that.

  4. #4
    Liaison 20774's Avatar
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    Doug -

    Well, if it returns to idle after slowing the engine down, then likely the weights and their pivots are fairly dirty. Yes, they are under the front engine cover. Probably a good idea to unhook the battery ground to be on the safe side before you remove the cover...don't think it's critical on a /2 but couldn't hurt. This picture shows what the advance unit will look like...from Duane Ausherman's website:

    http://w6rec.com/duane/bmw/advance/advance6.JPG

    Before removing it, try pulling out the weights with a fingernail and see if they spring back into position or not. If they don't spring back, could be the dirt.

    The advance unit will be installed like the picture below. Using an allen wrench, remove that bolt that goes down the center. Then with it off the bike, give it a good spray with something like carb cleaner. You could use PB Blaster to loosen things up, but follow with the carb cleaner. Finally, I'd probably wash it with some water and blow dry it to get all the moisture out. Reinstall and then try the fingernail test again. If they still don't spring back, could be those small springs are too weak. New springs can be purchased...I believe they come in different lengths so getting them in the right spot would be important.

    TimingChestUpper.jpg
    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!

  5. #5

    Advance springs are a good start

    I would also check the condition and routing of the throttle cables for sure. They must be routed a certain way and properly adjusted.

    While you have the front cover off you should also check point condition/gap and timing, both static and dynamic.

    You should always shut the fuel off at the petcock before you shut down the motor. My practice is to shut off the fuel a good minute before I shut down the motor, when I know the bike will sit for more than a few hours I will let it idle on the center stand until the engine runs rough or erratic then I shut it off, this procedure drains the fuel out of the float bowls and reduces leaks and flooding issues. I do it with all my bikes with carbs and petcocks, "55 R 50 trough to the '78 R 100s with about 12 bikes in between.

  6. #6

    Thumbs up R60/2 weights

    Problem solved, one weight had a little slack. Loosened the fastener and pushed arm out to remove slack. Runs great now just in time for the cold rain up here on an island in Lake Superior.

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