water in carb

I have a single engine (951) 2001 Sportster LE. The engine seems to run fine. After 3 or 4 minutes, I get a leakage around one spark plug. While hooked to a water hose, and at idle, the leakage is gray (oil/water). While running at high speeds, on the river, the leakage is darker...

Its been a while since running my GSI. The last time we ran it, it would not throttle up without stalling. The shop told me it was the gas lines. I started to change them yesterday and I cleared the top of the carb. I then decided to run it for a bit and see if it would start. It did but...