First ride problems

[Mr Rogers]

Yeah black plugs are a sign of an overly rich mixture. Could be a number of things, poor ignition, mix screws set too rich, wrong float height, petcock leaking, (don't leave it on prime!! Prime is for exactly that, priming dry carbs. The stock petcock requires vacuum pull from the motor to flow in the On and Reserve positions. Leaving it on prime can flood your carbs, and your crankcase with gasoline. Smell your oil, if it's gassy, get rid of it and the filter pronto...gassed out oil will ruin bearings and cylinder walls..)

Do you need to replace the filter too? Could you just replace the oil if the filter is very new?

[maddoggmike]

I am going to say replace because the filter itself would have gas enriched oil soaked in and would eventually recycle into the bike. there not the expensive id replace it with the oil.