Detonation - cause?

[3hunerd]

Thanks all for the info. It won't be at least until this weekend before I can get some answers. Yep, a broken skirt would not be good. Speaking of skirts .. have to share a comment I saw on another non-motorcycle site - "short skirts cause me to slap my piston".

I'll try to post a sound bite too if I get a chance. I am really leaning towards piston slap - though Mazikeen's other thought could be it too, but this bike was not ridden much, and was well maintained.