New member - F650 warm starting issue - Page 2

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Thread: New member - F650 warm starting issue

  1. #11
    Bike
    F650 1997
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    Apr 2020
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    Bregenz, Austria
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    Quote Originally Posted by kuyajonathan View Post
    my initial thoughts are fuelling or ignition
    Decompression lever issue was on Chinese made/assembled singles, manufacturing/wear issue with decompression lever. Compression drop when hot Unlikely with KM 13000 mileage on yours , unless valve clearance minimal , closing further when hot, even at KM 20-25k rarely need reshimming .

    float levels/needles, choke mechanism- been mentioned, sounds like rich mixture to start ok with no or minimal choke, may need adjusting, see FAQ's for full info ,
    you say; " I know that the carbs were completely stripped down and professionally cleaned before I got the bike,"
    I am wary of verbal or service history , would not be first time in my experience of cars & bikes what was said to have done hasn't . maybe worth a check float levels, crud in bowls, main jets, needle jets blocked or worn? If runs / starts better after fuel tap closed bit of a pointer.
    Coil issue or plug lead corrosion Issues common with this model, especially when hot. Whilst you have a new battery (check terminals tight, vibrations loosens them, can cause this issue ) , suggest voltage check static & running, VR major issue with this model, causes all sorts of symptoms, should get about 13.6v max running, may exceed this briefly on start up. Again see FAQ's for detailed info.


    Thank you.

    I understand your comments on the service history 100%, however the bike was in storage for almost 12 years. I believe the carbs were completely stripped and cleaned because otherwise after 12 years the bike probably would not run at all. Of course, noone is perfect and it is conceivable that something was missed. Before however I start to disassemble half the bike to get at the carbs I will try the easier things first.

    I have renewed the plugs, caps and leads.

    Battery is ok. I removed and charged it a month or so ago after the winter break, however I will check the voltage as you say. What is the procedure for checking the coils?

    Regards
    Martin

  2. #12
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    Quote Originally Posted by Englischdude View Post
    When checking the idle mixture by the colour of the plugs, i assume the engine must be hot? How long should i let the bike idle vefore switching off and removing the plugs?
    I would leave the bike to reach its normal temperature with the fan just coming on. It needs to idle for a few minutes before you check the plug colour.
    2006 F650GS in Black
    9,300 Miles

  3. #13
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    I assume your bike has two separate coils in which case it's unlikely they are the problem.
    2006 F650GS in Black
    9,300 Miles

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  5. #14
    Bike
    F650 1997
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    Apr 2020
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    Quote Originally Posted by AWJDThumper View Post
    I would leave the bike to reach its normal temperature with the fan just coming on. It needs to idle for a few minutes before you check the plug colour.
    Took the bike out for a 20Km ride and left it idling in the garage for a minute before switching off. Here a photo of the plugs. If anything I would say a little on the lean side?

    sparkplugs_bmw_idle.jpg

  6. #15
    Bike
    F650 1997
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    Quote Originally Posted by AWJDThumper View Post
    I assume your bike has two separate coils in which case it's unlikely they are the problem.
    correct, two separate coils, one for each plug.

  7. #16
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    Quote Originally Posted by Englischdude View Post
    Took the bike out for a 20Km ride and left it idling in the garage for a minute before switching off. Here a photo of the plugs. If anything I would say a little on the lean side?

    sparkplugs_bmw_idle.jpg
    From the pics, it does look a bit lean. I would normally expect the top electrode to be light brown in colour and for the top of the thread to show some black soot deposits. However, I would let the engine fully warm up and then allow it to tickover for a bit longer (5 minutes) to see what state the idle mixture is in. The colour of the plugs in your pics is more likely to reflect the mixture during the 20k km ride out!
    2006 F650GS in Black
    9,300 Miles

  8. #17
    Bike
    F650 1997
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    Quote Originally Posted by AWJDThumper View Post
    From the pics, it does look a bit lean. I would normally expect the top electrode to be light brown in colour and for the top of the thread to show some black soot deposits. However, I would let the engine fully warm up and then allow it to tickover for a bit longer (5 minutes) to see what state the idle mixture is in. The colour of the plugs in your pics is more likely to reflect the mixture during the 20k km ride out!
    will do, just need to plan a stop along the way and take the plugspanner with me. If I let the bike run in idle for 5 minutes in front of the house ill have problems with the neighbours, the austrians are somewhat conservative in that respect, otherwise a lovely bunch! Will post back with the results during the next couple of days.

  9. #18
    Bike
    F650 1997
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    Not managed to get the plugs checked after a long idle yet, however one thing I noticed yesterday was my idle speed is just over the 1500 mark (the needle swings a little), so I tried to reduce the idle speed. I could not reduce the speed at all to within the recommended 1200-1400, however it would INCREASE when adjusting the knurled idle speed knob. What could be the reason? I do have aftermarket bars on the bike, but there is no change in engine speed when turning the bars to the far left or right, so I am assuming the throttle cable length is ok. I did have the tank off several weeks ago to change the spark plug leads but I did nothing to the cabling. Maybe too high engine speed at idle could be contributing to the warm starting issue?

    Thanks in advance for your feedback.

  10. #19
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    With a conventional carb, there are two separate controls for adjusting the tickover speed of the engine: one is the throttle stop which is set via the knurled knob and the other is the fuel/air screw at the front underneath the air intake. The normal technique is to adjust the mixture at each step to achieve the best engine response followed by the throttle stop to achieve the correct tickover speed. You continue until you find the optimum set up which can take a bit of practice. However, I would also check that, with the throttle stop backed fully off, the butterfly valves fully close.
    2006 F650GS in Black
    9,300 Miles

  11. #20
    Bike
    F650 1997
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    Quote Originally Posted by AWJDThumper View Post
    With a conventional carb, there are two separate controls for adjusting the tickover speed of the engine: one is the throttle stop which is set via the knurled knob and the other is the fuel/air screw at the front underneath the air intake. The normal technique is to adjust the mixture at each step to achieve the best engine response followed by the throttle stop to achieve the correct tickover speed. You continue until you find the optimum set up which can take a bit of practice. However, I would also check that, with the throttle stop backed fully off, the butterfly valves fully close.
    Thank you for the info. this is still ongoing, however I now have a well-known interim issue, namely access to the idel screw. I can access the right hand side without ans special tools, but the left hand side is impossible. Nevertheless, i could determine that the carb on the right hand side was set to LESS THAN 2 turns out, bearing in mind the factory setting is between 4.5 and 3.5 turns out this is definitely lean. I have ordered a tool for accessing the left side screw, but it will take a week or so to get here.

    Question: is it a problem if the two sides are not set equally? I could adjust the right hand carb to the corect factory setting, the left hand side when the tool gets here. As it is a single cylinder, would idle setting difference between the ttwo sides of the carb be a problem or not?


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