Ok, so I'm new to the novelty of engine revving and getting some serious crackles. I don't over indulge in it too much but when I do some times when revving the whole Rev counter goes red and cuts the engine so the revs drop to zero rpm. But then is fine again and free to rev. I don't go mad with it, I Rev it for about 20secs if that.

What's going on? Just some safety mode? Or something to worry about? I don't ever rev when even remotely cold. And only done it twice.