Wow, serves me right for going to bed! Thanks for the replies guys!
(this is all theory, learned from different motors)
If you're near redline in 3rd gear, the motor is spinning at 7500-8000 rpm. If you then select 2nd, the forward motion of the motorcycle if all factors allow
will attempt to spin the motor at a much higher rpm, regardless of whether fuel is being delivered to the motor or not...I'd have to find some numbers and do some math...but it wouldn't be double
redline in 3rd gear....say 12,000 rpm or so...again, assuming the wheel maintains traction, the clutch is fully out, and the motor can overcome the deceleration due to engine breaking.
Motors have a redline for a number of reasons, in some designs, the valves float, in others weaknesses in the valvetrain can cause the motor to lose it's timing...if the latter happens, bad things can occur. Floating valves occur when the mass of the valve cannot be overcome by the valve spring and the valve fails to close in time. In that case, it's _possible_ for the valve and piston to be in the same place at the same time. If the valvetrain loses it's timing by breaking a belt or jumping a tooth, the same thing can happen. It's why Ducatis are desmodromic, they pull the valve UP as well as pushing the valve DOWN.
In a big meaty stock V-8 (without really expensive reciprocating parts), going much past redline can be a very bad thing...But it's got great big slugs of metal for pistons, and it's redline is up close to the mechanical limit of it's parts.
I had a dentist once who picked the wrong gear in his porsche...944...with a timing belt. Very expensive lesson.
Since the K motor is a smaller, lighter, motor, with direct application of the valves, and a timing chain...and if the clutch was not fully locked up...then the motor might have seen 9000-10,000 rpm. Death to a big bore motor, but I guess not to this one, based in-part on the overdesign of the motor. (Knocking on wood) Needless to say, I wouldn't want to do it again.