Hi Grumpy, have checked valve clearance, the exhaust was spot on but the inlet was slightly tighter ( 0.05+ 0.04 =0.09mm ), done slight adjustment. Gave the mower a little try, wouldnt kick over on compression, so turned motor back by hand tried again, kicked over and "backfired" at same time. It is actually coming from the aircleaner region ( felt it through my hand as me dad was kicking mower over ).
