06 450 Breather / Airbox mods...

I did mine today, heres some pics

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The '06 and up models are NOT wet sump engines. The oil tank was moved from the frame and integrated into the front of the crankcase, but it's still an isolated volume separate from the crankcase and sump. The engine still has a feed (oiling) pump to take oil from the tank and send it to the lube system, and a return (scavenging) pump to suck it up and move it back to the tank, so in that regard, it isn't any different.

In fact, there's nothing any different about the Gen2 YZ450 that should or would cause it to have any greater tendency toward pulling sand up the breather, and in all the desert and dune riding I've done, I haven't had any trouble.

People have reported this as far back as 2000, at least, particularly when stalled or starting in water, so it really is not that new. If you think your riding conditions present an increased hazard, you should modify it, otherwise, it's not that much to worry about.

Thanks for the correction on the wet sump mis-information. You are right that a lot of guys back to 98 complained of sucking water up the breather when the bike would stall in the water (due to not having the carb vents relocated to prevent this) but it wasn't until 06 that I heard of problems with sand creeping into the head area through the breather. I think I'll rig something up on my bike just to be safe, it sure can't hurt anything.

I know this is unrelated but can anyone give me the info on the oil filter drain bolt modification on the 06 yz450

If it goes into the boot, the air filter protects it from drawing in dust. If you just hang it in the air box, you need some sort of filter.

Here are some pics of how I did mine. I used the stock hose, cut it to add the ABS "T" I got from Home Depot (for oil catch) and thats it. Originally I put a foam filter in the PVC end cap but it kept blowing out. Years later I have never sucked any dirt in (without a filter in the end). I believe the only time this can happen is if the tube is "submerged". I am interested in doing the WR air boot as all I would need to buy is the elbow and boot since my hose is already routed. This would make cleaning the air box easier (by removing the hose). Any one ever try a check valve so that you could maintain crank case vacuum?

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I tried a check valve setup on my old 00 426 but I had a hard time finding a valve that didn't have a high cracking pressure. Something similar to the stock gas tank vent would be ideal.

I tried a check valve setup on my old 00 426 but I had a hard time finding a valve that didn't have a high cracking pressure. Something similar to the stock gas tank vent would be ideal.

Yeah I was thinking it would prolly need to be fabbed up. I was thinking a "reed" style as they tend to be very light back pressure and quick to close.

I was thinking a "reed" style as they tend to be very light back pressure and quick to close.
There should be an air box drain or similar reed type extension that could be added to the bottom of the OEM breather tube when you have a T in the line. If you run across one, let us know. IMO, that would be the perfect setup.
If you run across one, let us know.

I sure will...

One option I have thought about (since I have a CRF as well) is the oil drain back reed. Its stainless and about 1/2" by 1" and very "light" pedal tension. I replaced it last time I was in the bottom end, ill dig around and see if I still have it.

I varied from the Yamaha breather kit....instead of the oil trap tube, I put a fitting in the case (where it's baffled) and t'd down to there. Ran the hose up from the t to the filtered side of the intake.

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I was considering running the oil catch down to the breather hose that goes from the bottom of the crankcase to the dry sump tank (on AF bikes) but I dont know if I want the clutter.

If you dont over fill your oil than very little to zero will get squirted into the breather. (I have only ever accumulated a couple cc's ever in the several years ive had it routed to the air box)

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