I have a 1994 R1100 RS with 48,000 miles. Recently it felt like the throttle bodies were becoming out of sync. I had replaced the throttle cable in the beginning of the summer and assumed that the cables had stretched. It also was time for an oil and filter change.

I changed the oil and did a quick sync, airscrews onlyt. The bike seemed to run a little smoother on my way to work. On the way home, however, it was back to running rough.

Today I set the rocker arm sideplay adjustment to approximately 0.005", and confirmed that the intake valve was 0.012"freeplay and the exhaust valve freeplay was 0.014". The odd thing was that even though the plugs were removed it seemed difficult at near top dead center to turn the engine over using a wrench on the crank shaft. I assumed at the time that I was just fighting compressing the valve springs.

Upon starting the bike up, it sounded like there was someone inside hammering on the side of the engine case with a ball peen hammer. The engine sounded nothing like it had when properly tuned up. It was VERY rattley sounded like there was no oil in it. The engine does not quiet down after running for long enough for the oil pressure to come up. It sounds like absolute CRAP, as if I give it any throttle or, god forbid, I ride it, I will be picking up wadded up parts after it violently comes apart.

I have gone back through the valve train adjustment. The valves are set correctly and the rocker arm sideplay is correct. There is the proper amount of oil and it is circulating.

I didn't make any other changes so why does the bike make the hammering noise? It almost sounds like there is a severe rod knock and that the auxilary drive shaft is loose or the auxilary drive shaft chain is stretched or loose.

Has anyone experienced this? Where do I start short of assuming a rod bearing and tearing the entire engine down? I've done engine work on a succesful open wheel racing team and am comfortable doing the work and sure of my abilities. But this is the first oilhead I have worked on and this has me perplexed. How did it go from a seemingly simple throttle body out of balance is to knocking like a jack hammer sitting overnight. Help!