Hello! I have a 1993 Savage which i turned into a bobber. I changed the tank, the tap and  the carburetor has been cleaned up. Petcock is now blocked. New air filter (cone)
I did first tests yesterday.

When i let the tap open for a moment (engine off) and then i start the engine it spit out gasoline through the exhaust. Once all the gasoline has been removed it start and run normally.
Any guess?
(float issue? tap not adapted?)

Tell me if you need more informations on the bike.

I replaced oil couple days ago. 2 liters.

Yes the vacum line. I putted a plug on it.

The last  thing the fuel goes through to get to the bowl is the float valve, either the float level is set wrong, the float has a leak and fuel got inside making it sink ( shake it ), the float valve is worn (look for a ring around the tip), or fuel is leaking around the float valve seat ( the seat pulls out and there is an O- ring seal {fuel resistant } around the outside ).  You'll need to check all of these things, and keep an eye on your oil level ,if it's going up you'll need to change it again ,but find the problem first. Good Luck.

Thank you for your help. I will check that. I need to understand the carb anyway . Probably a missing gasket.
Im wondering how could the fuel rich the oil?? Which path?
To me there is a leak somehow in the carb, this leak flow to the explotion chamber and when i try to start the engine, compression push it out in the exhaust. And as soon as all extra fuel as been removed, it start and run normally.

fuel path, if the float valve doesn't hold , the float bowl over fills , gas comes up into the carb throat , it can run two ways,  into the cylinder(explosion chamber) or into the air filter box,  OR BOTH ( check and drain the box- there's a hose with a plug ,under the swing arm , replace the plug when done). If it runs into the cylinder it runs past the piston rings into the oil in the bottom of the motor.