crankcase oil blow by on WR400

All, I was alarmed at my oil level being down and topped it off. I then went for a romp around the neighborhood and was alarmed at the amount of oil spitting of the crankcase breather. I left a trail in spots. The hose follows the factory routing. If I didn't overfill it, Maybe I have the wrong dipstick in it? How long is the factory stick? It does seem a bit down on power. Starts like a champ. Compression seems OK. Plug is black at circumfrence and light brown electrode. Throwing this all out there iin case it's important. Any ideas? Re-route the hose? All replies appreciated!

dj

It sounds over filled.

To check the oil level you must run the bike for 2 mins (untill warmed up) then turn it off. Let set for about 20-30 seconds then check the fuild level. If you do not check it in this way and you check it cold after it has been sitting you WILL over fill it.

Thanks! I'll check it out.

Oil change with filter for me takes about 1.5 US Qts. That will put it right at the top of the stick. Also note that a little bit of blow by and oil dripping is fine and normal. After a ride I will find the lower end of the tube coated with oil and dust. The area on the frame behind the outlet will also be coated with a layer of oil & dust.

As for the oil checking procedure- these motors have a "dry sump" system. This means that when the bike is running the oil is pumped up to the tank in the frame. This is done to keep the crank from spinning in a pool of oil. SO- you have to run the engine untill warmed to pump the oil up to the tank. Then let it settle, then check it. If you try to check/fill the tank after the bike has sat too long it will have drained back to the sump. You will end up putting too much oil in the motor.

If you need a little more information you could try to search the forum for oil change help. Let us know what you find.

My '00 WR400 has a bit of blowby out the breather tube, will leave a couple of oil drips on the garage floor when parked after a hard ride. I bought this bike from a friend who bought it new, it has had the blowby from day one. The engine does not lose a measurable amount of oil between changes. As already pointed out, check for overfilling.

I just bought a 99 WR400 doing the same thing. I changed the oil and it was way overfilled, about 2 quarts, maybe more. The guy I got it from stated he thought he had over- filled it. It must be checked with a warm engine he was checking it cold.

My 02 WR 426 dose same thing And it is not over filled maybe this is normal I hope

It sounds over filled.

To check the oil level you must run the bike for 2 mins (untill warmed up) then turn it off. Let set for about 20-30 seconds then check the fuild level. If you do not check it in this way and you check it cold after it has been sitting you WILL over fill it.

Actually, after you have the bike up to operating temp and running for several minutes, you want to check the level as soon as possible after you've shut it off. I recently sat in on a Yamaha service seminar where they showed a very interesting video demonstration of what happens. In the demo, they had a glass tube attached to outside of the test bike's oil sump...which showed what the oil level did when the bike is shut off. It climbs quite a bit. If you wait too long, or if you didn't have the bike running for a long enough period of time, you get a false high reading. The demo pointed out how it was incorrect procedure even if you had run the bike for quite a distance...like you'd do if you rode it home...shut it off to open the garage door...fire it up and pull it into the garage...shut it off and check the oil level. This short runtime, even with a warm engine, also gave a false reading.

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