WR450 Gas in the oil?

Has anyone elts had this problem?

I have about 200 miles on my 06 wr450 and have done all the free mods (except the grey wire) and the jd jet kit. The last 2 times I have changed the oil I have noticed the oil level was very high and smelled of gas.

I asked the dealership about it, and they said that the petcocks on the yamahas are known to leak and may be flooding the engine and the fuel is mixing with the oil.

I checked the petcock and dident notice it leaking.

Any ideas on what would be causing this, and is it dangerous for the bike?

I was reading the posts on the grey wire and how it changes the timing to allow for the change in the throttle stop. Could having cut the throttle stop without cutting the grey wire be the cause?

Any help or ideas would be most appreciated.




Do you leave the gas on when its parked? The carb can flood, the extra fuel will run into the air cleaners and/or the intake. If it gets into the intake, it sets on top of the piston, eventually, it leaks past the rings and into the crankcase. This leaking past the rings does wash all residual lube off the cylinders, so it starts up, its dry. This will lead to rapid ring wear (called cylinder wash) so if you park if for a long time, turn the fuel off. If its doing it on short parkings, you may have a float level problem.

NEVER believe a Yamaha dealer.

they may have the best products, but honesty isnt a genuine yamaha part with a profit attached.


I always turn the gas off, and usually turn it off then run it for a few moments to get rid of some of the gas before putting it away.

Any other way it could happen or any idea on things to try.

I was thinking of disconnecting the fuel line while not in use.



You asked is it dangerous, YES if the fuel ignites behind the cylinder you have a bomb under you, get it fixed ASAP.

The dealer has admitted there is a problem, get him to fix it for free, is it under warrenty?

i never turn the gas off on my 06 and its in my house.never had a problem at all with it.all mods done as well as jet kit.never smells of gas either.did have carb off?

I have an 05 with the same problem. The oil was olive green and smelled like gas. The guys at the yamaha service center said it most likely is the float needle not properly seating. The float bowl then floods and spills over into the intake. From what toyota said, the fuel in the airbox sounds familiar, because i had fluid in the that clear bowl at the bottom of the airbox. I checked the float needle and it is now seating properly and i put fresh oil in the bike. I'll wait to see if it does it again. I bought the dealer AIS kit and did all the modes, yz screw, baffle removed, snorkel removed, grey wire, new throttle needle, and 48 pilot jet. don't know if problem is fixed yet?

I am currently experiencing this problem! I have yet to find a solution to it, but the bike is flooding...the exhaust is smoking and the plug is fouling....

I keep pulling the plug, cleaning it...then the bike fires up...then dies, and wont start again...

Does anyone etlts have a jd jet kit. I am wondering if it has something to do with the tapper on the needle jet. I dont remember having this problem before I had the jet kit installed. I wonder if it could be leaking out through from the new tapper and then flooding into the engine?

Forget about the JD jetting kit causing this problem! The only thing that can cause this is the float level or float valve seal. Dirt or particles can get caught on the valve and not allow it to seat and shut. The rubber o-ring may also deteriorate and need replacement to complete the sealing of the fuel flow into the carb! The float pin arm may be bent preventing the float from floating up to the seal position. etc. etc. and like Toyota says always turn off your fuel when not riding your bike. :thumbsup:

Oil can smell of fuel if your running very rich. The petcock on the 05 is not exactly horizontal in the off position so it is easy to leave it on a bit. I always check it is lined up exactly with the "off" mark.

The reason your plug keeps fowling is that the bike is running very rich. If you also have a problem with fuel in your oil or fuel dripping on the ground the problem is more than likely your needle valve is not sealing. On newer bikes it could be, 1) Dirt between the needle and seat. 2) Incorrect float level. On older bikes, and maybe some newer bikes if your unlucky, it could also be, 3) The needle and seat may be damaged and need replacing. 4) Fuel may be leaking into the float.

Regardless of whether your petcock is on or off, fuel should not leak into the carb and therefore the engine. The needle valve and seat's only job is to control the flow or completely stop the flow when the bike is running or not running. Although it is good practice to turn fuel off when you're not riding.

There is absolutely no chance that the JD Jetting kit or the needle jet will effect the seal of your needle valve or let excess fuel through while not running. However, it is a possibility that whom ever fitted the kit may have damaged or upset an adjustment.

I agree with Indy 450, the only way I see it is the needle & seat are not closing off the fuel passage. I have seen all diferrent types of debris cause this. Remove the bottom of the carb (3 screws) & turn on the petcock, as fuel dumps from the float raise the float with your fingers. All the fuel should shut off...No drips etc... if any fuel is passing by the seat / needle something is the matter, needle wear, debris, align etc....

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