Bit of a newbie question..

My bike is four stroking when I'm attacking big climbs. I'm going to start looking at needle clip position/air filter first and reckon it's a simple enough fix but I did start to wonder about what happens when riders rev their engines to clear them before big climbs. Mine tends to clear when I hold it wide open for a few seconds as well. Is that clearing the carbon from the plug or something else?

If an engine has been idling for some time, or you've just completed a long downhill run with the throttle closed, then a little fuel can collect in the crankcase and you may find that the engine will hesitate very briefly upon reopening the throttle. A quick blip with the clutch disengaged should be all you need to keep this from happening. But if it stutters or four-strokes for more than a moment it's an indication that the engine is running rich so if the air filter and so on is in good shape you may need to adjust the jetting. Always jet from each end and work your way towards the middle, ie. do the pilot jet and air screw first, then the main, then finally the needle/needle jet. 

Is your bike 2 or 4 stroke? 

One assumes a four stroke is intended to fourstroke on climbs and therefore not likely to be a souce of concern?☺

Good assumption. I was told by a 4 stroke rider that their bike was 4 stroking, I asked if it was like having the choke on and yes it was. 8 stroking is something else. 

Thanks all, yes it's a 2 stroke. 

Good explaination oldjohn, I'll check the obvious things over the weekend.

Cheers,