Originally Posted by Sirio2127

Do you have any clue as were its leaking?. I have a list of thing you can do to minamise leaks that can efect tune. First is remove the carby use a fine pin to cearfully remove the 2 o-rings inside the engine block try just to grab the edge of the o-ring with the sharp end of the pin. Once that is done inspect them as sometimes when a carby is installed from new out of box they can cut a small bit off the o-rings as you slide the carby in. I sugest you take the stock ones and go to a shop that sells o-rings and get some new ones the same size and replace them in the block. 2nd is remove the carby retainer nut you must do this in order losen the side with the screw with the carby in the crank case and push on it as you losen it so it pushed the side the bolt screws to out. Remove that side and then use a hex key or very small screwdriver and push the outher side out. If you push them in to were the cut is made in the crank case for the nut to tighten on the carby you will damage the o-rings on the retainer nut. Check the o-rings on the retainer nut if they are marked replace them. 3rd is remove the carby ball link and the carby dust protection boot. With this step you have 2 options if you use the stock sirio carby boot you should clean all the oil from inside the carby dust protection boot and the carby with some metholated sprits or unleaded fuel. use a high quality super glue or CA glue put some in the grove in the main carby body were the dust protection boot sits being cearfull just to get it in the grove then replace the rubber dust protection bood and the ball end. If you are worried about glueing it you can use a novarossi or rb nova based engine one 12 and 21 size they are much tighter fitting and there is no need to glue them. If the engine is still leaking it could be from one of 3 places the back plate from under the head button or glow plug. but most likely its from the front bearing. Do not worrie about that they all leak all the time. The only way you can slow this down is with a rubber sealed bearing and even then it will start leaking not long after. The only thing you should be worried about is if paformance or tune is being afected If the engine is very very hard to tune and to get it to hold a tune Then It could be sucking air eather through the carby or front bearing. Dose your engine run good and dose it get good paformance. By the looks of your track id probaly be running a mid to high gear ratio It looks very free flowing and high speed? Regards Jeremy.