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Discussion Starter #1
OK, more on my ongoing saga with this bike. The miss seems mostly to be between 1000-2000 RPM at light throttle loads, it even pops back through the intake. If I give it a handful of throttle it runs fine up to about 7000 RPM where it misses again. The general consensus is plugs/wires. I'm only skeptical because the bike only has 10K miles on it now. Am I thinking wrong that 12 year old plugs go bad from age?

Thanks, for putting up with me guys,

Robert
 

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seems to me you should just drive it, see if it settles down with some miles, sitting is generally not good for any motor vehicle - or you could start throwing money at it
 

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I had same issue with my '99 that sat for 2 years. I put in a new battery and started the engine. Once a tremendous amount of smoke cleared, I took the bike out for a test. Like your experience, there was a great deal of spitting and sputtering, especially when extra power was called for. I put some injector cleaner into the gas and ran the bike for about 20 miles in 3rd gear, occasionally revving up to near red line. The next morning I started out on a 1000 mile trip and was a little concerned about the misfire although is now was less frequent. 100 miles later, the misfire was gone and the bike pulled as when new. I have 60K on the clock, plugs are original, valves have never been adjusted, air cleaner was inspected, blown out and re-inserted. Only other maintenance has been oil, filter and rear-end oil changes. Bottom line: I theorize the plugs became oxidized while the bike sat, and good hard running took care of the problem.
 

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Discussion Starter #4
larrydreed said:
I had same issue with my '99 that sat for 2 years. I put in a new battery and started the engine. Once a tremendous amount of smoke cleared, I took the bike out for a test. Like your experience, there was a great deal of spitting and sputtering, especially when extra power was called for. I put some injector cleaner into the gas and ran the bike for about 20 miles in 3rd gear, occasionally revving up to near red line. The next morning I started out on a 1000 mile trip and was a little concerned about the misfire although is now was less frequent. 100 miles later, the misfire was gone and the bike pulled as when new. I have 60K on the clock, plugs are original, valves have never been adjusted, air cleaner was inspected, blown out and re-inserted. Only other maintenance has been oil, filter and rear-end oil changes. Bottom line: I theorize the plugs became oxidized while the bike sat, and good hard running took care of the problem.
Thanks, Gary and Larry, I bought the bike in NY May 11 and put 1880 miles on it right away getting home to Texas. I now have over 2000 miles since I bought it. I am beginning to suspect some connector or another has corrosion/resistance in it. Any suggestions on which ones and where to look?

Robert
 

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I would start with plugs and wires. The wires may be arcing against the head. Give them a very close inspection at least. I run NGK irridium plugs in mine, less money, and they last at least twice as long.
 

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Discussion Starter #6
14wntr said:
I would start with plugs and wires. The wires may be arcing against the head. Give them a very close inspection at least. I run NGK irridium plugs in mine, less money, and they last at least twice as long.
Thanks, do you have a part #. I have a chance to get to a BMW dealer Wednesday before the tech day.

Robert
 

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You might want to check or have someone check the pressure in the fuel rail for the injector system. Low or uneven pressure caused by a leak in the return hoses can show up as a slowly deteriorating condition like this. It can take over a year for it to finally quit running. Along the way you get burbles, poor gas mileage, slow starting and other odd symptoms that seem more like spark or bad gas problems. They might not be.
 

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Scouter-50 said:
OK, more on my ongoing saga with this bike. The miss seems mostly to be between 1000-2000 RPM at light throttle loads, it even pops back through the intake. If I give it a handful of throttle it runs fine up to about 7000 RPM where it misses again. The general consensus is plugs/wires. I'm only skeptical because the bike only has 10K miles on it now. Am I thinking wrong that 12 year old plugs go bad from age?

Thanks, for putting up with me guys,

Robert
To answer your question re: old plugs, NO, they will not go bad strictly from age. If this were the case, brand new plugs sitting on someone's shelf in a parts store would have a shelf life, and eventually go bad, if not sold and used. This is not the case. :D

These people who suggest throwing parts at it don't know how to troubleshoot and/or don't have the right diagnostic equipment. Even if the spark plugs are original- w/ only 10K miles on them, I'd be hard pressed to believe it's the plugs unless the gap has changed some how, or there's a crack in the porcelain tower. Remove the plugs, inspect, clean, gap, checking for evidence of breakage or worn down electrodes. BTW, I'm going on the assumption the OEM plugs are what you have, whether original or replacements, which if replacements, would have even less than the 10K miles on them.
 

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you could pull plugs check for them all being same color and also ohm out plug wires - I had a miss in my K100 that turned out to be wrong resistance plug wire, new plug wire fixed problem, the plug wires on my K1100 were cracked badly with wire core visible but the bike ran perfect
I think plugs that have been in an engine for 10 years and run infrequently will age differently than those sitting new on the shelf - missing at an idle is a sign of a possible failing spark plug
 

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Discussion Starter #11
gary45 said:
you could pull plugs check for them all being same color and also ohm out plug wires - I had a miss in my K100 that turned out to be wrong resistance plug wire, new plug wire fixed problem, the plug wires on my K1100 were cracked badly with wire core visible but the bike ran perfect
I think plugs that have been in an engine for 10 years and run infrequently will age differently than those sitting new on the shelf - missing at an idle is a sign of a possible failing spark plug
Thanks, Gary. I've got a good Fluke meter, what should I be reading for ohms? Also I used to think that misfiring usually occurred under high loads (pressure) in the combustion chamber. I have had plugs that would spark fine at atmospheric pressure but would not spark under compression. Am I mistaken? My miss is mostly in the 1000-2000 rpm range under light throttle. If I grab a hand full it runs fine.
Robert
 

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agree about more pressure no spark but I have had plugs cause poor idling in my cars - the wires on the K100 and K1100 were 5 ohms - have not found any info re K12 wires but it's basically the same system so suspect they would be the same - if you measure all 4 they should be the same, if you have one that is different and that spark plug is a different color then that would be suspect - these plug wires are extremely expensive at least K100 ones are up here - 60 to 90 dollars each

have you had the engine redlined bouncing off the rev limiter - german engines seem to need that once in awhile (my experience anyways) - as others have said different animal over 6K revs
 

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Scouter-50 said:
Thanks, Gary. I've got a good Fluke meter, what should I be reading for ohms? Also I used to think that misfiring usually occurred under high loads (pressure) in the combustion chamber. I have had plugs that would spark fine at atmospheric pressure but would not spark under compression. Am I mistaken? My miss is mostly in the 1000-2000 rpm range under light throttle. If I grab a hand full it runs fine.
Robert
Seems like the rule of thumb is approximately 1000 ohms per inch of length is acceptable. I would not necessarily discard a plug wire just because it's a couple thousand ohms difference from other wires. It's quite possible to have four wires w/ four different resistance values, especially if they're different lengths. A spark plug wire could be prone to have more resistance at higher temperatures, especially the cheaply made aftermarket ones.
 

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bikerj said:
Seems like the rule of thumb is approximately 1000 ohms per inch of length is acceptable. I would not necessarily discard a plug wire just because it's a couple thousand ohms difference from other wires. It's quite possible to have four wires w/ four different resistance values, especially if they're different lengths. A spark plug wire could be prone to have more resistance at higher temperatures, especially the cheaply made aftermarket ones.

they have to be pretty close for the electronic ignition, I had 2 marginal wire on my K100 which caused a bad miss at idle - the wires are the same length - on the 2 valve engines if plugs got 2 thou out of tolerance they would not run properly- I could always tell when the gap got bigger - pulled set correctly, ran perfect
 

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Sorry, I'm coming in late to this discussion, but did you try running some Sea Foam through?
 

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Discussion Starter #16
gpolakow said:
Sorry, I'm coming in late to this discussion, but did you try running some Sea Foam through?
No, not really sure what Sea Foam is. I assume it's one of those snake oils like Lucas products that actually works. Could you identify the exact product and a possible place to purchase it?

Thanks, Robert.
 

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Scouter-50 said:
Thanks, Gary. I've got a good Fluke meter, what should I be reading for ohms? Also I used to think that misfiring usually occurred under high loads (pressure) in the combustion chamber. I have had plugs that would spark fine at atmospheric pressure but would not spark under compression. Am I mistaken? My miss is mostly in the 1000-2000 rpm range under light throttle. If I grab a hand full it runs fine.
Robert
For the spark-plugs wires, you should find a resistance of 6.3 to 6.5 K Ohms end-to-end (from coil end of the wire -to- the end of the cap).

They are made by BREMI or BERU for BMW and are generally marked with a resistance value. See 2 attached pictures - they are BREMI in this case - the wire is marked ONE (1) K Ohms and the cap is marked FIVE (5) K Ohms. Obviously this should add up to 6 K Ohms, but depending on the wire length, you will get a bit more for the longer wires.

NOTE: this will NOT measure external damage or cracks that could cause arcing in operation when hot. So checking the resistance does not tell the whole story...
 

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Discussion Starter #20
sailor said:
For the spark-plugs wires, you should find a resistance of 6.3 to 6.5 K Ohms end-to-end (from coil end of the wire -to- the end of the cap).

They are made by BREMI or BERU for BMW and are generally marked with a resistance value. See 2 attached pictures - they are BREMI in this case - the wire is marked ONE (1) K Ohms and the cap is marked FIVE (5) K Ohms. Obviously this should add up to 6 K Ohms, but depending on the wire length, you will get a bit more for the longer wires.

NOTE: this will NOT measure external damage or cracks that could cause arcing in operation when hot. So checking the resistance does not tell the whole story...
Thanks, John. This is exactly what I was looking for! I do not like throwing parts at something without proving the old part is bad. I am the senior HVAC tech at a small college in Texas and have to deal with co-workers that change parts because they don't know what is wrong. I'm slowly correcting this. Thanks again for your information.
Robert (a displaced Canadian from BC)
 
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