That's what happened to my motor. Was about 6100 on the clock. Retainer came loose on one of the intake valves and it started tapdancing on top of the piston.
Mmm hmm....I did get a decently low motor shipped up here from FL for only $600 Mounted it up and dyno tuned it and it made more HP than the old motor did when I first got it I do have a spare head with about 3K miles on that I was going to use to replace if anyone needs one 06-07 600
Not to derail the thread but I recently bought a 2008 GSXR750 with 9,000 track only miles on it. Previous owner said he checked the valve clearance recently with no adjustments necessary. If items were broken I would assume he would have seen it at that time. Do these have similar problems or are the valve components different?
hadn't heard any issues with busa motors. unless they are trying to run a bunch of boost or nitrous without a proper tune. Turbocharged guys are seeing ~300hp/125 ft lbs at the tire on conservative single digit boost #s on stock engines.