I have had a similiar issue with my rides in the past, and nearly every time it is related to fuel bowl level. Aftermarket kits that I had purchased, forgot from where, didn't last a year and leaked past the needle. What I ended up doing was making a fixture to hold carb, feed it with a facet pump at 3psi, and check/adjust fuel levels. I've had newly rebuilt carbs leak, not all kits are the same. Just a side note, a fixed fuel/oil mix 50/1 I've noticed does smoke a bit at idle. The VRO's, are not fixed in ratio, it changes the mix throughout RPM range.