First off...Hello to everyone. I'm new to the forum. Here's my dilemma.. I've had 4 CBR900's. I kept a 99 in mint shape, However it has a major problem. I think the carburetors are faulty. The gasoline goes right down and mixes with the oil. The mechanic I had at the time did me dirty. Switched parts on me and this is one of the problems caused by the switcheroo of parts. Can someone tell me if this is being caused by my carbs or the fuel petcock (gas selector / swithch). It's costing me quite a bit of money and plenty of worries. Cause if I dont check and I ride with this thin oil, my engine is gone. HELP !!!

 

the problem is your carbs or at least one of them. the float is sticking or out of adjustment. pull the carbs and then holding tham as they would sit in the bike reapply fuel to them and see which one leaks gas. then remove the float bowl from that carb and see if the float is stuck or the needle is stuck or has dirt in it. you may also get away with tapping the bottom of each carb with a small hammer or screwdriver handle and see if you can get the problem to go away.