06' YZ450F Concern/Prob?

I Just purchased a 06' YZ450F, My first Fourstroke Race Bike, a little over a week ago. I noticed the other day when I was just easing around on it that the engine started chattering, kinda like the valves, and that the Radiator overflow hose was spewing coolant out of it. Almost like it was overheating. Is this normal or should I be concerned?

Also, Is it normal for gas to drip out of the cylinder head breather tube after riding the bike, and then parking it. Any help is greatly Appreciated

No it isnt normal for gas to come out the breather.Usually when OIL comes out of the breather it means you have too much oil in it.Drain your oil(remember there is 2 drains) and fill it back to spec in the manual any try that.

Well, I heard today that somebody i know had his new yamaha 450 lock up on him. Worst news i have heard yet about the yamahas. I have been a yamaha loyalst since before the 400 days. I sure hope Yamaha fixes it for him.

Well I found out that it wasn't gas coming out of the Cylinder head breather hose, it is actually oil. I still need to know if that is normal though. Also still wondering about the bike seemingly over heating, and forcing the coolant out.

The radiators are pretty small on these bikes and don't hold a lot of coolant. They don't take to sitting around idleing or just putting around too well. They need to be moving to keep air going through the radiators.


You have the answer in front of you, it is a "fourstroke race bike" that is not made for racing or at least riding at a reasonable pace, it seems like it was overheating because it was. I have seen this happen a few times on the start line seeminglyt without any consequenses. Take Lowedogs advice & get some air flowingthrough it.

If the bike has not been run in properly with decent amounts of throttle then it will breathe past the rings. Read & understand the manual & it will be the best (& most reliable) bike you have ever owned. Neglect it & it will be very expensive

Sounds to me like you let the bike idle too long before riding it and it got too hot. I start mine after I'm completely dressed and ready to ride. I idle for warm up about 1min max or less and go ride. (Do not need to warm it like a 2smoke)

Oil out of the breather hose is normal if the oil level is too high. Double check your oil height - make sure your bike is warmed up when you check it or it will not show true height.

The noise you are referring to may be the normal sound that these 4 strokes make - but to be sure ask someone who has owned one of these at the track or elsewhere to listen to it.

And where do you ride in Alabama? Big Cedar/Mill Creek?

Congrats on your new purchase and ask away for any questions you have :ride:

Thanks for the input. I was kinda figuring you had to have air passing through it, but just wanted to check. Don't want to mess up a new bike. I haven't been to any of those tracks. I'm from North Alabama so I hit tracks mainly close to my area. Which have become few and far between. I used to go to Kilpatrick, Moontown, and Rocket City Raceway, but they've all closed or relocated. I haven't had alot of time to hit the tracks lately and have been sticking mainly to my practice track, but I plan on trying to go to tracks like Tunnel Hill and Winchester as they're not to far from where I live. I've always wanted to hit some tracks in mid alabama though. They apppear to have awesome layouts.

Could also be like so many from that come from the factory that the bike is running a little lean and is overheating more easily.

I have just clocked up 3.5 hours on the hourmeter on my 06yz450f. Ran the bike in for the first hour then changed the oil & filter. The oil had a strong petrol smell to it. After two more rides the bike dropped a little oil out of the breather wich also smelled of fuel. I figure the rings are not bedded in properly yet & I will need to change the oil a bit early this time.

Superxking if your bike has just pushed some coolant out don't stress about it. It could have also been because the radiators were full from new & without an overflow bottle like a streetbike it might push some fluid out when the coolant gets up to normal temp.

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