BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

here is one more for you guys to chew over..
About 3 weeks ago I started experiencing a brief (less the 1 sec) when going throught the gears in hard acceleration. This was especially bad if you crank the throttle open in 6th gear....the bike would start to accelerate but all of a sudden it feels like the fuel was cut off for a moment (tank at this time is full).....you let the throttle back a little and it's ok...acceleration resumes. I have took the bike to the dealer last week for 12k service and explained the problem to him. After a regular "maybe you imagined it!" question, I assured the mechanic that I was capable of telling if there was something wrong. Here is what the dealer did after performing the 12K service:
1. took a bike to a test ride - found nothing wrong
2. hooked up to a computer - nothing wrong
3. took a bike for a test ride again - finally confirmed the problem exists
4. changed the coils (all) and took it for a test ride - problem still exists
5. found that 1 spark plug was cracked (changed all spark plugs) - problem still exists
6. hooked the bike back to the computer and checked specifically the crank shaft sensor - sensor passed 2 out of 3 times (it finally errored out)
7. they ordered the sensor and received it overnight.
After changing it, the problem was solved.
Cost of 12K service at BMW of SF is $450 + $30 for spark plugs (no labor was charged) = $480.
Did any of you experienced similar problems with your bikes?
thx,
Alex

I experienced something similar yesterday, but I wrote it off to the ASC kicking in, as it was quite cold out and I thought I hit an icy spot.

However, I didn't notice any ice (and I was looking, I can assure you). I'll keep this in the back of my mind in future - gosh I hope builtforcomfort doesn't get wind of this...

Thanks for the heads up!

Alex, At what RPM does this happen? Always at the same RPM? If you open the throttle less abruptly does it still happen?

Mark

My 1988 K75 developed a sensor problem years ago. I would start it in the morning, and after 8 minutes exactly, it would shut off. Hit the starter and it would re-fire. Replaced the sensors and it has been fine since.

Scott
1988 K75
2009 R1200R

tinytrains wrote:My 1988 K75 developed a sensor problem years ago. I would start it in the morning, and after 8 minutes exactly, it would shut off. Hit the starter and it would re-fire. Replaced the sensors and it has been fine since.

Scott
1988 K75
2009 R1200R

Just one quick comment - I believe it was likely the camshaft sensor that went jumblies up in this case. AFAIK, the hexhead engine doesn't have a crankshaft sensor.

It's #14 on: http://www.realoem.com/bmw/showparts.do ... g=11&fg=20

Your failure was the imfamous hall-effect sensors failure on the K series bikes. Fairly common, and a thermal fault, which is why it shut down when the bike warmed up.

The camshaft sensor should be a much simpler device - a simple reluctance (magnetic) pickup that detects the steel lump on the end of the camshaft at TDC. They used to fail on BMW cars with some regularity 25 years ago - after about 1990 it was very rare to have one fail. They are a very simple device (coil of wire wound around a core..)

Anyway - unless I hear of a rash of failures, I won't be looking to add it to my spare parts quite yet.. I do have spare coils, and EWS ring, and haven't needed a thing, proving Eilenberger's Law of Spare Parts.

celticus wrote:Alex, At what RPM does this happen? Always at the same RPM? If you open the throttle less abruptly does it still happen?

Mark

it usually happned around 5-6k rpm.....and only under hard acceleration

Ok. I did not realize the sensors were that different on the R's from the K's. The title was crankshaft sensor, so I went with it.

Scott