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Topic-icon Carburetor and ignition switch issues?

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6 days 23 hours ago #3640 by Corey
Corey created the topic: Carburetor and ignition switch issues?
BMW '73 R60/5

Here is a summary of what is going on:

First:
The bike was running well a few weeks ago, I was out for a long ride and the bike back fired and started to sputter and completely lost power - seemed like it was being starved of gas, I stopped and started and rode a short distance, three times, but the bike finally gave up the ghost. Couldn't make it home. I replaced the inline fuel filter, air filter and spark plugs but the bike is still not turning over. The the insulating cloth of the fuel line was saturated with gas at the connection to the left carb but that has seemed to have resolved. I did get it started (took a bit of time and it was not idling pretty) after the above mentioned maintenance work and took it for a spin but it still lost power accelerating from second gear into third. It is currently not turning over.

Second:
When I turn the bike off and disengage the key, the lights on the instrument cluster (mostly the battery charging indicator light) remain on. Not sure if there is a loose connection or my ignition switch is shot. I do have a new battery I purchased a month or so ago.

Thanks for any insight you guys may have!

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6 days 21 hours ago - 6 days 20 hours ago #3641 by Wobbly
Wobbly replied the topic: Carburetor and ignition switch issues?

Corey wrote: The bike was running well a few weeks ago, I was out for a long ride and the bike back fired and started to sputter and completely lost power - seemed like it was being starved of gas, I stopped and started and rode a short distance, three times, but the bike finally gave up the ghost. Couldn't make it home. I replaced the inline fuel filter, air filter and spark plugs but the bike is still not turning over. The the insulating cloth of the fuel line was saturated with gas at the connection to the left carb but that has seemed to have resolved. I did get it started (took a bit of time and it was not idling pretty) after the above mentioned maintenance work and took it for a spin but it still lost power accelerating from second gear into third. It is currently not turning over.


► You said "not turning over" several times. For clarity... you mean using the electric starter, correct ? The bike still turns over using the kick start lever, is that right ?

► Apologies, but your descriptions are so general, that it could be anything. Fuel, ignition spark, and compression are all it takes for an engine to run. Your problem centers on one of those 3 elements. A rudimentary inspection of those 3 functions will yield information allowing you to focus more quickly on the exact problem area and stop all the guessing. Guessing is NOT your friend.

Probable issues could be...
• Airhead valves tend to tighten up due to using the newer lead-free fuels which this engine was NOT designed to run. When was the last time the valve clearances were checked ? Tight valves are the Number 1 cause of compression loss on Airheads.

• If you have lost ignition spark, than it's most likely that your points have closed up. Every 2000 miles or so it's best to remove the front cover (after disconnecting the battery) and clean and gap the points. You'll also need to service the auto advance unit and apply a dab of grease to the ignition cam to keep the points block from wearing... and thus closing the points up. This repetitive work is why most owners convert to EI.

• Original fuel lines were not designed for ethanol fuels. Leaking fuel on the outside may tell a tale of rubber flaking off on the inside and working its way down to the carb, where it blocks the float needle or fuel inlet. I would advise you to buy 3 feet of 1/4" ID black automotive fuel line which should be marked "SAE J30" (to prove it can stand up to ethanol) and replace ALL your fuel lines. If you have trouble slipping it over the T-fitting, then heat the tubing with a hair dryer and lubricate the fitting. It's a nice, tight fit that needs no clamp.


I'd sincerely like to hear back after you work on this a bit more.

Don't hide 'em, Ride 'em !!
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Last Edit: 6 days 20 hours ago by Wobbly.

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6 days 20 hours ago #3642 by Corey
Corey replied the topic: Carburetor and ignition switch issues?
Yes, turning over meaning using the electrical starter, but it also doesn't start using the kick start lever.

No apologies needed, this is all very new to me, just starting to learn the ins and outs of an Airhead. I purchased the bike less than a year ago. I have no record from the previous owner when the value clearances were checked. I will definitely look into this issue, and cleaning an gaping the points, as well as replacing the the fuel lines.

I will keep you posted on my progress.
Thanks for the potential leads and taking the time to answer my post.

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6 days 14 hours ago #3648 by Wobbly
Wobbly replied the topic: Carburetor and ignition switch issues?
You're certainly welcome for the help. Remember though, the first place to start is always with the 3 functions. That will narrow down your list of culprits to a very manageable number.

Don't hide 'em, Ride 'em !!
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6 days 6 hours ago #3651 by 8244
8244 replied the topic: Carburetor and ignition switch issues?
I'm confused about what the symptom really is. It sounds like you are describing the engine actually starting as turning over, not the action of the starter physically spinning the motor when you hit the button.

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