I'm still running the stock 1978 "blue" coils, but have brand new adjustable voltage regulator and brand new wires with NGK plug caps from the guys at EME in Colorado. Yesterday I was just cruising at a nice 60 MPH for about 30 miles and all the sudden it sounded like the right cylinder bogged down and I slowed a tad. No loud noise or anything like that.
Pulled of the road, shut it down. Check fuel flow and it was fine. Carbs were rebuilt by me and at valves are set correctly. I'm going to call them good for now, for conversation sake.
Pulled both plug caps and pushed back on.
Started bike back up to head to gas station down the road and it ran perfect again. So I kept going... Ran great for the next 50 miles where I ended my ride at home.
I have a Noris point to still install, but does this sound like a symptom of possible bad coil? Or coil/point combo? I've been meaning to replace the coils anyways, so I'm good with just getting some and throwing them on to narrow it down.
Thanks guys!!!
I am not an expert on BMW coils, but this does not sound like a coil going bad to me. In my experience, it sounds like trash in the fuel or an intermittent electrical glitch.
If you're riding the bike how can you tell the Right cylinder had an issue ? What do the plugs look like ?
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
I assume right cylinder for it "appeared" the bogging sound came from. But I do wear a full face helmet so I could have assumed that is what I heard. I didn't have any tools on me to check the plugs, but I will tonight. I'm a tad rich on purpose for now, but maybe too much of a tad. I'll report back on my findings. I'd be very happy if it is just a turn of a screw or clean of an inline filter!!
Is this a bike you've just gotten out of winter storage and running for the season ? A bike that has been running for serval months ? Or one that's just come out of long-term storage ?
Your profile says you're in Chicago, so I'm not quite sure of the back story.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
No, i had it running and out on the street all winter. As long as it wasn't snowing or too much salt on the roads.
Without a lot more information and specific tests, your question is going to be very hard to diagnose on the web. Right now you had a single occurrence, until it repeats, there's no proof you even have an issue to diagnose. It's like asking us to plot a graph with one data point.
The only thing I can advise you to do that will help with any certainty is start carrying a full complement of tools so that you can do things like remove the spark plugs and compare colors and condition.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Thanks wobbly. I'll reach back out if it happens again and also run a few checks and tests to make sure it wasn't just a fluke. Though I may just throw in some new coils anyways. I feel like buying myself a small present. Cheers!!
The problematic "Crack-O-Matic" coils are double tower coils for electronic ignition. Mine started failing when water got in the crack during a hard rain storm. The single tower coils you have reportedly almost never fail. I agree with Wobbly about trash in the fuel. You might try checking the filter screens.
Bob
► If you want to spend money, then buy some new metal core plug wires and spark plugs. Plugs usually last a long time, but can also be easily damaged by old fuel, incorrect tightening, incorrect mixtures, etc. If I was sure there was an ignition issue, then plugs is the first place to look.
► When was the last time your engine was strobe timed at high RPM ? I see an earlier post mentioned converting to electronic ignition. You'll be forced to buy a strobe lamp for that installation, so buy one now and check the current points setup.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Advertisement
