Discovered Dirt In Carb! Opinions Requested - 07 WR450

I don't think it is possible

I found the same thing! I think the airbox should seal firmly against lip of the cage and not the center post.

I modified the center of the cage for a tighter fit and am picking up some gasket material to make a spacer that fits between the lip of the cage and the filter causing the pressure of the cage retaining wire to seal the edge.

I believe this is the problem that permits dust to bypass the filter! :thumbsup:

Rick,

Did you discover this before or after you dirt in the carb problem? In other words, did this solve your problem?

Discovered after! :thumbsup:

I don't think it is possible

When I bought my bike it had a K&N filter which is rigid so it doesn’t require a cage. After reading several threads saying the K&N is crap I started using twin air filters but with no cage. I always grease the sealing area and haven’t found dirt in the hose when doing a filter change so I guess this is OK??

Pull the top of your carb and tell us what you find.

I've found this kind of dust in my 06 WR and an 03 YZ. I honestly have no idea where its coming from other than the vent hoses as my filters do seat securely and I use plenty of oil and grease on the sealing lip. Uni filters, twin airs and stock.:thumbsup:

Hey Guys,

I pulled my carb tonight and low an behold I had dust in the slide area also. No dirt in the bowl however. Not quite as bad a Ricks's but pretty darn close. I have about 400 miles, about 20 hours on the bike. I am almost 100% sure that the problem is this screen not pinching the edge of the filter down. I ground down the screen guide post and I cleaned every thing up. Just try pinching the edge of the filter with your fingers, if it is not compressed there is no wonder it leaks air. Yama really fornicated the K-9 on this one!!

Just another thought. Due to the way the cage is held against the box, I believe it is very easy and probable that the cage rarely sits evenly in its stock configuration. That is, it is very easy to tilt the cage to one side or the other thus allowing one side to even more easily allow in unfiltered air. Hopefully the post grind fix should also remedy this scinario

I think some people have gotten lucky using a lot of grease, or have just not noticed the dust getting by. I really think this is a big problem.

I used my cage as a template and created a doughnut shaped gasket from 3/16" rubberized cork gasket material and used RTV to cement it in. Between that and modifying the center of the cage I'm certain there is complete sealage. I chose to modify only the cage. Mvryder chose, it appears, to modify only the airbox. Whatever works!

The cage doesn't rock at all when seated.

I agree completely with mvryder that this is the cause for the dust bypassing the filter.

Clark, you may want to add this to the sticky...

I used my cage as a template and created a doughnut shaped gasket from 3/16" rubberized cork gasket material and used RTV to cement it in. Between that and modifying the center of the cage I'm certain there is complete sealage. I chose to modify only the cage. Mvryder chose, it appears, to modify only the airbox. Whatever works!

The cage doesn't rock at all when seated.

I agree completely with mvryder that this is the cause for the dust bypassing the filter.

Clark, you may want to add this to the sticky...

I have the dirt/grime in the slide area too. Noticed it a while back. I added a gasket and improved my filter prep routine. The air filter could be part of it, but this thread also mentions about the breather hoses being a source of the dust. Think I'll look at filtering the hoses too. Instead of running them to the air box, I'm going to try re-routing them to an area where I can wrap the ends with filter foam material.

Every bike I've ever owned or worked on with an FCR (WR/YZ/CRF/DRZ) has had dust above the slide area. I don't think the air cleaner is the culprit here. It appears to come in through the top cover or the throttle shaft. If it were the vents I would think you would find a bunch of junk in the bowl but I've never seen that. Take off the top cover and look inside and you'll see way more dust accumulated than in the bore area. At any rate given the reliabilitely history of these bikes (except the CRF of course) I don't think it's a big issue.

Sorry, I disagree.

This problem is causing these bikes to suck dust. It is not normal. The dust is inside the air boot, not just the slide. It is a problem, not just normal wear and tear dirt bike stuff.

Yama really fornicated the K-9 on this one!!

Does that mean they screwed the pooch on this one?:thumbsup:

A filter cage design issue notwithstanding, I'm with PD on this one - I've always had a fine layer of dust in the boot, top of the carb cover, throttle slide area, bowl, etc., with my 99s and now with my 07.

That doesn't mean I'm not going to try the cage mod you suggested. However, I'm willing to bet I'm still going to have a fine layer of dust in my intake system. Will keep the forum posted on how it goes, but it will be a while as I'm down recovering from shoulder surgery.

Has anyone performed the discussed mod and gotten some dusty miles in, seeing a marked improvement? It seems like many of us are just figuring it out now and have not tested it yet. Has anyone seen a before and after already?

I've been concerned about the amount of dust I found in the front of my carb. Here are a few thoughts on this subject:

These are dirt bikes, not surgical instruments. I'm sure some dust is going to get thru no matter what. Good filter hygiene will reduce the dust. As long as the particles are small, it shouldn't score the inside of the barrel (I assume). Most of it probably gets blown to smithereens during engine combustion.

The guy who lives in the rainy northwest may not see as much carb dust as the guy who races desert here in SoCal.

I'm curious, where is the smithereens on the 07 WR450? I tried to find it in the parts manual but couldn't locate it. I called my local Yamaha dealer and told the guy that I figured I needed a new one since I had so much dirt being blown into it. He put me on hold and got more of his co-workers on the call to discuss.

I guess someone they knew had a serious accident and was killed from having a clogged smithereens because everyone on the phone was crying except me.

I may as well fix this too!

The guy who lives in the rainy northwest may not see as much carb dust as the guy who races desert here in SoCal.

Is this the rainy northwest you are talking about?

Copyofpicture12.jpg

Or is it this?

07290716221.jpg

We definitely put our filters to the test up here in our little corner of paradise! :thumbsup:

Sorry! I couldn't resist the smithereeens thing...

Below are two links to photos. One is a photo of a clean rag, soaked with carb cleaner that was used to swab the intake of my 35 hour old WR. I'm uncertain how much of the residue is from backfire into the carb or from dirt entering the intake from the carb.

The second is the airbox mod I did. I decided not to re-route the carb vent lines so that I can see if there is any affect of this mod.

Intake Dirt

http://novomaris.com/images/motorcycles/intake_dirt.jpg

Airbox Mod (Raw, I haven't cleaned the airbox up for re-installation)

http://novomaris.com/images/motorcycles/airbox_mod.jpg

Sorry! I couldn't resist the smithereens thing...

Below are two links to photos. One is a photo of a clean rag, soaked with carb cleaner that was used to swab the intake of my 35 hour old WR. I'm uncertain how much of the residue is from backfire into the carb or from dirt entering the intake from the carb.

The second is the airbox mod I did. I decided not to re-route the carb vent lines so that I can see if there is any affect of this mod.

Intake Dirt

http://novomaris.com/images/motorcycles/intake_dirt.jpg

Airbox Mod (Raw, I haven't cleaned the airbox up for re-installation)

http://novomaris.com/images/motorcycles/airbox_mod.jpg

Great idea! Repeat the rag swab test after several hours of dusty riding and let us know what you find.

BTW - Vintage George Carlin quote: "I use to think the smithereens was a division of the armed forces. "

Sorry, I disagree.

This problem is causing these bikes to suck dust. It is not normal. The dust is inside the air boot, not just the slide. It is a problem, not just normal wear and tear dirt bike stuff.

OEM filter or quality aftermarket, Maxima FAB1 oil and white lithium grease around the base of the filter (per the manual). No dust in the airboot. I just had to make my first valve adjustment after ~4000 miles. One intake was .001" tight. As for dust in the carb I was referring to the other area that ingests dust in the FCR carb which is above the slide.

I asked James Dean of JD Jetting fame for his opinion. Here is his reply...

James Dean:

The dust came thru your air filter. I've seen much speculation about where the dust on the carb cover comes from. The majority of the airflow thru your carb comes thru the air filter, and in order for the filter to flow at a fast rate, it cannot capture the finest particles. The splattering of dust on the cover is usually directly above the passage that allows air to rise up into the cavity above the slide when the carb slide rises and drops, in the center/front of the slide. The remainder of dust is spread thruout the upper area. Any air pulled in from the carb's throttle shaft or around the cover seal is minimal and is not the source.

The only suggestion I have is to clean the filter often and use a generous amount of oil on the airfilter.

James

Thank you Mr. Dean!

I asked James Dean of JD Jetting fame for his opinion. Here is his reply...

James Dean:

Thank you Mr. Dean!

That has been my gut feeling all along. As I've mentioned in the past, no matter what my filter brand/oil combo is, I always see a very fine layer of dust in the boot every time I clean my filter. It's happens with my WR400

and continues with the 07 450. And when I do get to cleaning the carb for whatever reason, the slide cover area and the slide usually has a build up of dirt also. I've just learnt to live with it.

As far as dirt in the bowl, I'm going to try and address it with one of these things: http://www.7602racing.com/prod_t6cf.php I have two on order. If nothing else, it ups the bling factor!

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