'09 WR450F Crankcase vents (3). Remove one?

So, Yamaha in all their wisdom put three crankcase vents on my '09 WR450F. Normally, I'd say that's a good thing, avoiding condensation in the oil and rebreathing crankcase vapors (the EPA folks like that, I don't from a performance standpoint) - especially since they routed the vents to the airbox so I don't have to. :doh:

The downside to all this is that there's a vent hose that comes off the starter gear that crosses in front of the fuelscrew and pretty much takes up all the space under the carb to the point that I can't turn a GYTR fuelscrew with gloved fingers. :snore:

Question: Is anyone running a bike that has that particular vent plugged off and have there been any issues with oil contamination or other things by doing that? I'd expect some more moisture contamination since it's a dead-end high spot if it's plugged off, but I'd really like to be able to turn the freakin' fuelscrew... :lol:

David, I am of the opinion that a manufacturer would not go to the trouble to add things like an additional crankcase vent if it were not needed. I beleive the vent is on the start idler housing because it is a high point that could easily trap water/fuel vapors as you identified. Have you considered simply re-routing the hose?

David, I am of the opinion that a manufacturer would not go to the trouble to add things like an additional crankcase vent if it were not needed. I beleive the vent is on the start idler housing because it is a high point that could easily trap water/fuel vapors as you identified. Have you considered simply re-routing the hose?

Hi William,

Yep, that's the one on the starter idler. I'm with you on the engineers probably know what they're doing, but as we know, there's a reason for mods and aftermarket parts; was just hoping that someone solved this "new" (ok, new to me) problem already. :snore:

I thought about it and that's probably what I'm going to do. Route that particular hose all the way to the right side of the bike then loop it back to the Y connector for the other two hoses. It'll be tight, but not so horrible as it is now.

Another thought is that someone makes a fuelscrew with a cable attached to it and a thumbscrew that mounts on on of the other carb bolts. If the cable is long enough maybe it will fit on the back-left float bolt. :doh:

I might stop by Bert's tomorrow and take a look at it - I'm sure that I saw one there.

I feel your pain. I got sick of trying to deal with that problem as well, so I got one of these bad boys and man is it nice!

http://www.r1dean.com/cart/index.php?main_page=product_info&products_id=48

They say they can get tougher to turn in time, but a little bit of WD-40 fixes that problem. I find it much easier to use than trying to turn the old fuel screw with one finger. Little pricey but well worth it!

Oh yeah and it does attach to the back left float bowl screw. It comes with a philips screw but I quickly ditched that and used the stock allen head screw.

Even if you re-route hoses and cables, it's still going to be a pain in the ass to get to the old fashion fuel screw, this is the ticket.

That's the one! Thanks Ranger85.

The way the hoses are routed from the valve cover , down the side and eventually into the airbox, I believe the hose to the starter gear head is there to allow any oil in the hoses to drain back into the engine cases, lube the starter gear and "not" enter the airbox. WR Dave

There wasn`t any hose at the startergear on pre -07 models, or was it??

The way the hoses are routed from the valve cover , down the side and eventually into the airbox, I believe the hose to the starter gear head is there to allow any oil in the hoses to drain back into the engine cases, lube the starter gear and "not" enter the airbox. WR Dave

Excellent point, Dave! :doh:

Thanks Dave!

All I know is, I can't get my fat, old, gloved fingers in there to turn the freakin' fuelscrew. :doh:

That and I don't want to break something that shouldn't be broked. :lol:

An aside: I was looking at the '09 WR450F manual, and noticed that Yamaha hasn't updated (at least some of) the drawings - like the shock mounts have extra parts in the drawing that aren't on the bike. Anyway, for me that brings into question how much some of the things Yamaha does really matters. So frustrating sometimes. :snore:

Ok, I took another look at this today.

First, I stopped by Bert's (West Covina, CA) and picked up a R&D remote fuelscrew that was hanging on the wall. :snore:

I'd have bought it from the TT store, but they already had it, so maybe next time...

Also looked at the '09WR450F and '09WR250F starter idler housings. (Fwiw, Bert's has a hella lot of bikes there, and some pretty good prices on previous year bikes for a major retail shop - at least imo...) The 450 has the vent, the 250 does not. So, that tells me that fuel and water vapor shouldn't be an issue since that's a high spot on both bikes, and WR_Dave is probably right about it being an oil drain back to the crankase (which makes a lot of sense from where the Tee is located).

So, I can probably just plug the vent and the bottom port on the tee and be fine. Maybe check for oil in the airbox and save some $$ on the remote fuelscrew. But I have it now and am interested in how it might make it easier to tune the bike. :doh:

Another thought I had on the idler vent hose is that it might help with reducing the crankase pulsations from reciprocating volume changes since there would be 50% more hose diameter than two hoses alone, and the pulsations might have different timing in different places in the engine. Ugh. might be best to just install the remote fuelscrew and not mess with the vent hose any further. :lol:

For at least 6 years the vent just went from the head to open air. The new configuration is nothing more than making it epa-compliant i.e. closed loop. You can pull the hose off the idler gear housing and let it vent to air if you like. I wouldn't plug the hose as then there will be nowhere for the oil to go but into the airbox. Personally aside from the access issues I like the new configuration since it solves the problem the old set up had with water crossings. Sounds like the extended fuel screw is the hot ticket.

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