So the bug was playing hard to start a few weeks back so replaced a few bits and it turned out to be the coil. However I also noticed at the time that the plugs were NGK BP6ES so swapped them for new BP5ES. Fine briefly then started to run even worse with dreaded white smoke. Could not get the mixture right so before stomping off indoors I put the old BP6ES plugs back in and hey presto a significant improvement. In theory they should be the same just run cooler. Anyone else have a plug preference? It’s an 850 engine.