SPARK PLUG size?!?!?!!?!?anyone plZ?!?!!

[AZTIG]

hello people!!! can you guys tell me which the right size for 49cc mini pocket bike it is BM7A or BM6A both NGK :D ...im comfused which is better!!! :confused: when i match it BM6A is longer a bit....

[datalorr]

the number on the plug denotes heat range.NOT ALL PLUG MAKES USE THE SAME SCALE. it mean how quick or slow heat disapates from the cylinder head my FG uses a NGK BPMR7A (hot plug) the same heat rang but made by champion would somthing like a RCJ4,. if i fitted a NGK BPMR4A to my FG the engine would overheat and damage the plug and piston, if i fitted a NGK BPMR9A the plug start to oil up due to the combustion temp being too low, which is better than a melt down, if your unsure use the hotter plug

hope this helps a little