2003 YZ450F Oil leak please help

Hey all, I am sort of new to this whole motocross thing and I love it. I bought an 03 YZ40F from a friend and have an awesome time on it,what a fun sport I must say. Yesterday we went out riding and I started to smell oil burning. I could see oil on my right radiator but did not know where it was coming from. Today I pulled the radiator off cleaned everything, and noticed that right above where the exhaust manifold goes into the engine there is a hole where the oil is spraying out of onto the radiator. I can look right into the engine and I dont think this is supposed to be like that. Now there is a screw on the right side of the engine that looks like it is supposed to hold something in there. If it is ike a car I am thinking that there is supposed to be a breather valve there or something. I have been looking for pictures to see if there is supposed to be a plug or something in there. If anyone can help me out with this I would greatly appreciate it. Thanks and safe riding to all.....Greg

That is a hole for the decomp. Yamaha uses a cheapo plug that from time to time gets blown out. A search here for "Decomp Plug' or 'Decompression plug' will show you many threads. Best of liuck.

Thanks for all of the help guys, I will get the plug in and be ready to ride next weekend. I did go back out and look at my breather line and it is clear from the top with no kinks. I even disconnected it and used low pressure air to blow it out. Thanks again for all of the help....Ride Safe!!!!!

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