OT but 4-stroke :-)

Motorsickle: 1987 Honda CBR600 ("Hurricane"), 20k mi. In-line 4 cyl. liquid cooled, HP (11-1 compression, 4-valve, redlined at 12k rpm, etc)
Bike has been running reasonably well (tiny, tiny lo-speed miss) up until the ugly, Ugly Aug. heat wave, during which I didn't ride.
Tried to start it about a week ago, it spluttered, idled on choke, died when I tried to rev it up. I could choke it up to maybe 3k rpm but it wouldn't take throttle at any choke setting. Goes "clunk-clunk" and dies when throttled.
It has fouled plugs maybe twice in the 18 years I've had it. This morn I fire it up for 2 min., then check to see which pipes are hot. The only cold pipe was on cyl. 3.
So I get down on the ground and torture my hands to replace plugs. The cyl. #1 plug was totally fouled, all black. The #2 was oily, I think it wasn't properly torqued (near impossible to properly torque in given space). #3 and #4 looked reasonably clean. Not what I expected.
With 4 clean plugs, I fired it up and it did the same. Idled on choke but wouldn't throttle at all.
I'm not sure where to start looking.
Anybody got a feel for such circumstances?
What all would make a 4-stroke go "clunk-clunk" and die when throttled?
Thanks, Puddin'
"Mit der Dummheit kaempfen Goetter selbst vergebens!" -Friedrich Schiller
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