HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
trailhead2004

Oil in Airbox Thread

33 posts in this topic

:thumbsup: At the risk of beating a dead horse...

Here's the situ. I've been prepping my '08 WR450 for DS riding and the most recent addition was a Trail Tech Stator and Regulator (I'll post to the modifications forum with that later). I installed the stator by lying the bike on it's right side and doing the rest of the work under the left side cover, then bolting that back up. When I got done doing the stator install I worked on the wiring mods, which took about a day.

When I took the bike out the first few times, they were mostly low speed runs, RPM fairly low and top speed about 50mph. Saturday, I took the bike out to the freeway at speeds up to 75 or 80 mph. When I arrived at my friend's house about 20 miles away, I noticed oil running down the left seat stay out of the airbox. I just turned around and rode mellow home on backroads.

When I got home I "drained" the oil out of the airbox and got about 5 to 10 cc's out of it. Of course, when I was cleaning up the mess the first time I looked over the crankcase vent hoses checking for kinks or other blockage and found nothing. I checked the oil level as described in the manual. I wiped everything down as best I could and put it back together and took off on another ride. This time was another speed run, 70 to 80 mph, maybe 10 miles. When I got home I found another 2 to 5 cc's of oil in the airbox.

Modification wise, I have the usual jetting changes, AIS removed, airbox opened up as described in the GYTR instructions, yadda, yadda, yadda.

After reading through as many posts as I could find regarding oil in the airbox, I decided it was time to throw this out to everyone else.

My suspicion is that the airbox is building up vacuum and drawing oil/vapor out of the crankcase vent(s). My proposed solution is to throw a crankcase vent filter (K&N or other) on the vent tube. I know I should place it as high as possible to keep it further from dirt, water, small animals and children, etc.

Finally a question. Has anyone else had this same experience? What did you do to solve it? Does this solution sound like complete insanity to anyone else? (I don't really want an answer to that one).

Generally, the bike runs very well. No sputtering or coughing. I occasionally get a little bog off the line but at this point I'm not too worried about that.

Any info would be appreciated.

BTW, my search words were: crankcase, vent, oil, airbox, and I also picked off the WRXXX forum and the engine technical forum to try to narrow it a little. I eventually just searched all forums.:p

TIA,

trailhead2004

Share this post


Link to post
Share on other sites

i had the same thing happen to me but it was because i forgot to drain the oil from both drain plugs. the dipstick looked good too but it had way to much in it so it blew out the air box.

Share this post


Link to post
Share on other sites
i had the same thing happen to me but it was because i forgot to drain the oil from both drain plugs. the dipstick looked good too but it had way to much in it so it blew out the air box.

+1.... I changed the oil from the start opening both drains but would never get anything more than a drip out of the left side drain, so I basically abandoned that method and would just drain from the lower drain plug. My oil level always looked good:excuseme: One day, after a day of desert riding, I noticed the infamous oil leak from my airbox and was puzzled. I checked the oil level and it was right up to the top of the dip stick hole (too full:eek:)

I found that I had always failed to remove the dipstick first before draining from the leftside drain plug, thus creating a vaccum in the oil resevoir and not allowing the oil to drain.

The odd thing here is that my oil level always looked good after an oil change:excuseme:

Share this post


Link to post
Share on other sites

If oil blowing out the breather in small quantities is normal for the externally routed breather vents of the YZF models (and it is), why would anyone think it would stop happening just because the hose is routed to the air box? That would be courteous, but you can't expect manners from machinery.

If you think it's excessive, the cause could be over filling the engine oil, or tired rings.

I found that I had always failed to remove the dipstick first before draining from the leftside drain plug, thus creating a vaccum in the oil resevoir and not allowing the oil to drain.

The odd thing here is that my oil level always looked good after an oil change:excuseme:

Gotta pull the dip stick on the aluminum framed models. The reason the oil level looked OK when it was over full is simply that there is no more room in the tank on the late model for any extra oil. Anything over capacity gets forced back out the pressure balance line (the black external hose) and back to the crankcase.

Share this post


Link to post
Share on other sites

could it be you over oiled the air cleaner

i am embarressed to admit i have done this.....

seeemed ok, when i installed. but there was way more oil then the sponge element could hold... made an awfull mess...

also plugged up my idle jet... was idling horrible for a couple of rides. after correcting the problem :thumbsup:

cheers

good luck

Warts

Share this post


Link to post
Share on other sites

I had this happen a week ago.but after reading how many people have had this happen to them I didn't worry too much. Just put in a new air filter and did another oil change. Can't hurt a fourstroke with oil changes

Share this post


Link to post
Share on other sites

I';m beginning to wonder if I actually DID remove both drain plugs when I did the first two oil changes. I think I'll just drain all of the oil when I get home and refill to see if that helps the problem.:thumbsup:

trailhead2004

Share this post


Link to post
Share on other sites
I'm beginning to wonder if I actually DID remove both drain plugs when I did the first two oil changes. I think I'll just drain all of the oil when I get home and refill to see if that helps the problem.
Remember to remove the dip stick if it's an '07-8.

Share this post


Link to post
Share on other sites
:thumbsup: At the risk of beating a dead horse...

Here's the situ. I've been prepping my '08 WR450 for DS riding and the most recent addition was a Trail Tech Stator and Regulator (I'll post to the modifications forum with that later). I installed the stator by lying the bike on it's right side and doing the rest of the work under the left side cover, then bolting that back up. When I got done doing the stator install I worked on the wiring mods, which took about a day.

How did the Stator and Regulator install go? I just ordered one for my bike.

Share this post


Link to post
Share on other sites

Does the TT stator produce any more juice then the stock?

Share this post


Link to post
Share on other sites
Does the TT stator produce any more juice then the stock?

In talking to Baja Designs , they said that the stock stator with their ground float mod produces a ~120W output. The TT stator is a 100W stator but I believe since it is rewound it is stronger (not in watts). Could somebody with elctrical knowledge help explain.:thumbsup:

Share this post


Link to post
Share on other sites

My suspicion is that the airbox is building up vacuum and drawing oil/vapor out of the crankcase vent(s). My proposed solution is to throw a crankcase vent filter (K&N or other) on the vent tube. I know I should place it as high as possible to keep it further from dirt, water, small animals and children, etc.

Finally a question. Has anyone else had this same experience? What did you do to solve it? Does this solution sound like complete insanity to anyone else? (I don't really want an answer to that one).

I've never liked the way these are routed to the airbox. Like you, I felt that the intake might have some vacuum effect on the breather. I also don't care for the fact that the breather can basically draw dirty air. At the time I de-restricted mine (also an '08), I ran two separate breather tubes and capped them with Uni crankcase filters. I'm not exactly sure why Yamaha has two vent hoses (one on the valve cover and one on the lower cases near the starter- -connected by a "Y" fitting) unless the lower hose is just supposed to accept the oil that overflows from the top vent back into the cases. Anyway, I routed both upwards with the idea of keeping the oil from ultimately escaping. The one from the lower cases terminates with the Uni filter beneath the tank right about where the AIS used to be. The one from the valve cover was routed upwards and it passes through the frame from the right side to the left right where the hose is that connects the top of the two radiators together. The end of that breather and filter is zip tied to the top of the left radiator. This has apparently worked pretty well as never a drop of oil has escaped through either vent. I can tell you that the breather off the valve cover flows very well as you can hear it quite readily as the bike is idling. Almost has that VW kind of sound or similar to a Husaberg with its under tank air filter if you've ever heard one. It's really not noticeable as you ride though. It's hard to tell what the lower breather is doing as you really can't hear or feel any airflow (in or out) from it. One downside is that you do notice some engine oil smell due to the top breather being routed high like that. When it comes to bike washing time I just put a plastic baggie and rubberband around both to keep the water out. This may not be the hot ticket if you ride in super wet conditions though. It's mostly dry and dusty where I ride. :thumbsup:

Share this post


Link to post
Share on other sites
In talking to Baja Designs , they said that the stock stator with their ground float mod produces a ~120W output. The TT stator is a 100W stator but I believe since it is rewound it is stronger (not in watts). Could somebody with elctrical knowledge help explain.:thumbsup:

I don't understand why you went the TrailTech route. The BD regulator/rectifier and ground float mod would have accomplished the same thing (actually with a higher output) for a whole lot less:excuseme: Plus you would have had the reliability of the Yamaha stator.

Share this post


Link to post
Share on other sites
I don't understand why you went the TrailTech route. The BD regulator/rectifier and ground float mod would have accomplished the same thing (actually with a higher output) for a whole lot less:excuseme: Plus you would have had the reliability of the Yamaha stator.

Well then, let me help you. I f'd up when I put the stator back in after the BD mod and didn't put the yellow / white wires behind the bracket.:thumbsup: That left them exposed to the turning of the crank and eventually wore through. Want to guess what happened:confused: Bike no more wanna go forward:foul: This would be in the middle of some fantastic Kennedy Meadows trails.:p

The fun part is I called Yamaha and they don't not sell the wire loom by itself and the stock stator's are on back order with no ETA.:cry::p Hence option TT.

Share this post


Link to post
Share on other sites
I've never liked the way these are routed to the airbox. Like you, I felt that the intake might have some vacuum effect on the breather. I also don't care for the fact that the breather can basically draw dirty air. ....I'm not exactly sure why Yamaha has two vent hoses (one on the valve cover and one on the lower cases near the starter- -connected by a "Y" fitting) unless the lower hose is just supposed to accept the oil that overflows from the top vent back into the cases.
With the breather routed to the intake side of the air filter, it can be, and is, exposed to a slight level of vacuum. How much is influenced by how restrictive the filter is, which also means how clean it is, and by how much air is entering the carb. That, in turn, means that the vacuum is going to be the highest at high RPM and heavy throttle loads. The vacuum should not rise much over 4-6 inches of water (13.6 in/water = 1 in/mercury) with a good filter, though, so it isn't much to worry about.

You guessed right about the logic of the dual breathers. The one running up from the starter serves as a return route for a good deal of the oil before it reaches the boot.

However, you are wrong regarding the breather's ability to draw dirty air. In fact, with the hose connected at the air boot between the carb and filter, the only air that can be drawn into the engine is already filtered by the engine air filter. Some YZF riders concerned with the simple down and out routing of the vent on that bike use the WR parts to solve the problem.

Having the breather outlet in the intake stream is not a particularly big problem unless one overfills, or has some other situation going on in which there is an unusual and excessive amount of oil being exhausted from the crankcase. And of course, it's necessary to do this in order to pass emissions standards.

Share this post


Link to post
Share on other sites
Well then, let me help you. I f'd up when I put the stator back in after the BD mod and didn't put the yellow / white wires behind the bracket.:thumbsup: That left them exposed to the turning of the crank and eventually wore through. Want to guess what happened:confused: Bike no more wanna go forward:foul: This would be in the middle of some fantastic Kennedy Meadows trails.:cry:

The fun part is I called Yamaha and they don't not sell the wire loom by itself and the stock stator's are on back order with no ETA.:p:worthy: Hence option TT.

Gotcha!

My next post to you would have been asking if you wanted to sell the Yamaha stator (but I'll pass now!):p

Share this post


Link to post
Share on other sites
However, you are wrong regarding the breather's ability to draw dirty air. In fact, with the hose connected at the air boot between the carb and filter, the only air that can be drawn into the engine is already filtered by the engine air filter.

Grey - I'm going to go out on a limb and say the hose is actually connected to the unfiltered side of the air box. If I remember correctly, the very bottom left side of the air box opening (dirty side) has two holes - one for the oil/water drain (which has that clear plug on the outside), and the other for the breather hose. I'll check again when I get home.

Share this post


Link to post
Share on other sites

However, you are wrong regarding the breather's ability to draw dirty air. In fact, with the hose connected at the air boot between the carb and filter, the only air that can be drawn into the engine is already filtered by the engine air filter. Some YZF riders concerned with the simple down and out routing of the vent on that bike use the WR parts to solve the problem.

Mine had the breather routed to the dirty side of the airbox at the bottom, hence one of the reasons I put the Uni on it. The only thing on the clean (intake) side of the filter was the hose at the top of the airbox that the AIS system used to draw clean air. The crankcase breather is definitely drawing dirty air as routed by Yamaha , but I'm sure it is pumping out probably just as much as it is sucking in. :thumbsup:

Share this post


Link to post
Share on other sites

OK, I had the AIS fitting confused with the breather inlet. However, that means that there essentially is no vacuum applied to the breather at all. (the bike has a lot of plumbing on it, and I haven't had a chance to really look one over in depth)

And you are correct that the breather is a more or less balanced give/take thing. In fact, there is a net outflow. While the crankcase pressure created by the descending piston is reversed by the following upstroke, combustion gases escaping to the crankcase past the rings are not, and exit through the vent. When it becomes problematic is at very low engine speeds, or when starting or stopping, when there is time for the entire 450cc of air to enter the breather before the pressure reverses and starts back out. That's why YZ guys who ride woods get concerned with the stock YZ breathers.

But some have used the fitting from a WR air boot to run the breather to the fresh air side with a T'd in drain tube, ala CRF.

Share this post


Link to post
Share on other sites
How did the Stator and Regulator install go? I just ordered one for my bike.

The install went great! The only caveat is that since there is a little crimping of connector pins it pays to have the correct crimper for best results. I have the crimper so I was entirely pleased. I did a few test crimps before getting into the stator and I was unable to pull the wires from the pins so I feel the connection is sound.

I would say however that the Trail Tech instructions leave a little to be desired. They have a few pics but they really aren't very good.

The other issue" I had was the Trail Tech Reg/Rect would interfere with the left fork tube well before full lock. I solved that problem with a little creative grinding and cutting on the frame (See pics below). I'll take better pics later with the regulator off.

When you remove the regulator, there is a boss/bracket welded to the frame with weld beads at the top and bottom. Basically, I just cut out the edge of the bracket to give clearance for the wires (look at the yellow and red wires coming out from behind the regulator). I also had to grind a little bit of the posts for the bolts. The regulator wouldn't fit between the posts so I just took a little bit off, maybe 1/16 inch total.

After I got all the monkey f'ing accomplished I'm happy with the project results.

trailhead2004

http://i289.photobucket.com/albums/ll223/trailhead2004/IMG_5145_64kb.jpg

http://i289.photobucket.com/albums/ll223/trailhead2004/IMG_5144_64kb.jpg

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0