I have a '96 R1100R that makes a curious clanking sound on start-up, particularly when on the choke. It starts with no problem, but when cold and idling, particularly idling on the choke, I hear an irregular clanking which seems to come from the front of the engine. Here's a recording of it:
Recording of engine idling and clanking
In this sound sequence the engine is not quite full cold (I'd started and run it a minute or two a couple of times earlier in the morning), but not fully warmed up. The sequence starts with the engine idling with the choke off, then about 5 seconds into it the choke goes on (you can hear the engine RPM go up), there's the intermittent clanking sound, there's about 25 seconds of that, then I turned off the choke, the idle goes back to normal.
When the engine is fully cold the clanking will sometimes occur with the choke off as well, and once warmed up it doesn't do it at all. The engine seems to run fine otherwise other than occasional surging at steady throttle openings.
Any suggestions on what this might be? This is my first Boxer, so not sure if this kind of clanking is normal start-up noise or something wrong. I've pulled off the pulley cover to see if it might be something under there, everything looks OK.
Ideas? Thoughts? Suggestions?
Any help anyone can provide would be most appreciated -- thanks.
History of the bike: It was purchased in '96, ridden for less than 2000 miles, then put into storage until mid-2003, at which point a dealer serviced it and said they did all the right things to bring it out of storage (oil change, brake fluid change, check for leaks, etc.). An elderly gentleman then bought it, rode it for a couple of months, decided it was too big a bike for him, traded it back in. I bought it in December '03, and other than changing the tires (tires were original -- unworn but almost 9 years old), I haven't done much to it but add some accessories and put about 1000 miles on it.
For those with super-sensitive ears (and a fast connection), here's a link to the full-fidelity recording (1.5 Mb):