Smokin' Deal, or Smokey Deal...

[mlandon]

Just picked up a 1999 Roadster (non-ABS), fairly clean bike with 69,XXX on the clock. Initial start ups have been pretty smoky, the gray/white kind that hangs around. Started to clean and go through stuff and thought "what the heck, do a compression test." Got bike up to what appear to be operating temperature, but didn't take it out on the street. Pulled the plugs, pulled the fuel system relay, screwed in compression test, hit the starter. Dial on gauge jumped up to 90 PSI, but flattened out at 115 psi after about 5 seconds on the starter switch. Left and right cylinders acted exactly the same. Shot oil into both, big jump was to 100 psi, each cylinder maxed out at 125 psi. There was a healthy amount of oil residue and road grime around the bases of the cylinders before I started cleaning the bike (after the compression test.)

Question #1, book says anything below 120 psi is no good, anyone else's experiences with compression test results and anecdotes about the bikes performance, mileage would be helpful.
Question #2, could re-torque cylinder heads help in this situation?
Question #3, thought about Sea-Foam, 44K or similar combustion cleaner through fuel and crankcase, any suggestions?
Question #4, should I just go ahead and order new piston rings and tear it down? Any other riders pull a top-end on an Oilhead? What do I need to look for. My personal experience is a lot of wrench on VW, including numerous re-builds, many Japanese cylinder heads and a lot additional wrenching.

Any thoughts or suggestions would be appreciate.

[The Meromorph]

Most likely culprit is the rings, but it also could be valve adjustment.
The cylinder bore is Nikasil coated, and very hard, it is unlikely to be cylinder scoring.
Broken rings are unlikely with the pressures you are getting. Worn rings are possible at that mileage, but not usual. My personal guess is gummed up rings sticking in their grooves.
The best remedy I can suggest is an oil additive called Auto-RX.
http://www.auto-rx.com/
I have no association with this company. It is vouched for by the oil enthusiasts on BobIsTHe OilGuy.com as one of the few oil additives that is safe, reliable and effective. It cleans slowly and effectively and will free up gummed up rings. If that is your problem, it is far cheaper and less work than replacing the rings. Auto-RX makes a motorcycle variant called Cycle-RX
http://www.auto-rx.com/cycle-rx/index.html
designed specifically for motorcycles (and the same price). You could use either on your BMW as it has a dry clutch and separate engine oil. Both will work very well indeed. Cycle-RX works faster, with a shorter engine oil change cycle.

You might also do a valve adjustment (pretty easy on an Oilhead) just to make sure it's not that. A valve adjustment at that mileage is a good idea anyway.

[The Meromorph]

Just had another thought,
You did do the compression test with a wide open throttle?
Because if you didn't those figures are not useful at all, though they are believable if it's really OK and you just didn't have the throttle wide open,,,

[mlandon]

I have never done a compression test with wide open throttle - never seen it as part of the procedure, I'll give it a try when I get back to the bike...

Thanks for the input.