does that mean that the rev limiter is raised in neutral? or does the engine ramp up quicker than the rev limiter can suppress it?... also i used to race motocross, when we were jumping, and were nose down in the air, we pin the throttle open to use centrifical force to bring your nose up...now this happened all the time, is there a big difference between hitting the rev limiter on my 99 blade compared to my 08 crf450? what im trying to ask is how bad is it to hit the rev limiter on the blade.
The rev limiter only cuts the ignition, it is not an engine brake that stops the engine from spinning any higher. If you crack the throttle open at 1000rpm the engine has enough inertia to continue accelerating after the spark is cut. Increasing the revs up to the limiter with a little mechanical affinity in mind doesn't do any harm to the engine and it will happily sit there banging the limiter in neutral all day long.
Whether that is sufficient to damage the engine comes down to whether it's designed for it, and I would expect dirt bikes would have a healthy margin for that very reason. Of course, you wouldn't be doing it in neutral anyway as the crankshaft has very little mass, you would be leaving it in gear and using the centrifugal force within the rear wheel and tyre to alter the attitude of the bike.
The CRF engine though is a very highly strung thing prone to catastrophic failures under race use unless very closely monitored. I've seen a 450 engine that threw a rod and used the remains of the rod to cut the crankcases in half.
Exceeding the limiter usually results in rod stretch on the exhaust stroke with either the beam letting go, the rod bolts failing, or the bigend ovaling to the point that oil clearance is compromised resulting in metal-to-metal contact of the bearing shells at the sides and over-heating.
Simply put, exceeding the manufacturer-dictated rev limit (assuming the engine is factory built of course) is never a good thing for the engine, even if it stays together there's a good chance the rod has been compromised in some way.