Discovered Dirt In Carb! Opinions Requested - 07 WR450

Hi All!

It's cold enough now to swap out my needle for a richer needle (JD). I removed the card slider cap and to my horror I find dirt (I think) in the carb! There is both tan colored and black, slightly greasy stuff in the thing.

Please have a look at the photos in the links below (too big to post here)!

I'm running Twin-Air filter and the Twin-Air over cover with Twin-Air oil...

Is this normal? The bike has 35 hours on it...

The clean spot on the cap is where I wiped it off with my finger!

http://novomaris.com/images/motorcycles/cap1.jpg

http://novomaris.com/images/motorcycles/body1.jpg

http://novomaris.com/images/motorcycles/body2.jpg

Thanks!

do you run an inline fuel filter?

No inline fuel filter!

There is and always has been a very fine and very thin layer of dust behind the filter. Yes, the filter cage hole is plugged.

I just can't imagine that much dirt in the carb!

I run all four of the vent lines into the airbox on mine. No problems, no dirt, no nada...SC

I pulled the carb and cleaned! It was scary how much dirt was in the carb. Mostly above the slide. I just am not certain about the vent tube theory as explained over on the YZ forum. There really was a lot of dirt. Mr. Dean presents his theory and GreyRacer presents his. Both make sense and are opposing.

I also pulled my airbox. As I mention above there is always a very thin layer of dust behind the filter and I mean thin. I can't imagine that causing so much dirt in the carb.

Clark, how did you make the connection to the airbox and what about the bowl vent? Everything I read says to leave it hanging below the carb and this is the vent that JD implies as being the biggest culprit.

I'm not alone here! That much dirt HAS to cause big problems and HAS to be quite obvious to others...

I pulled the carb and cleaned! It was scary how much dirt was in the carb. Mostly above the slide. I just am not certain about the vent tube theory as explained over on the YZ forum. There really was a lot of dirt. Mr. Dean presents his theory and GreyRacer presents his. Both make sense and are opposing.

I also pulled my airbox. As I mention above there is always a very thin layer of dust behind the filter and I mean thin. I can't imagine that causing so much dirt in the carb.

Clark, how did you make the connection to the airbox and what about the bowl vent? Everything I read says to leave it hanging below the carb and this is the vent that JD implies as being the biggest culprit.

I'm not alone here! That much dirt HAS to cause big problems and HAS to be quite obvious to others...

Rick - I got ahead of myself on this one with out completely reading your original post (or looking at your pics). The thread in the YZ forum refers to dirt in the carb fuel bowl, which had been attributed to the vent tubes. Looking at your pics, my guess would be it's from the air filter. I also always have a fine layer of dust inside the boot after every air filter cleaning (on both the 99 400s and the 07 450. I only run the OEM filters.

Clark, how did you make the connection to the airbox and what about the bowl vent? Everything I read says to leave it hanging below the carb and this is the vent that JD implies as being the biggest culprit...

The 4 vent lines are long enough to come over the top and go into the airbox where the snorkel used to be. As long as the lines aren't kinked, there's no issue. If I wreck and gas leaks from the carb, it comes out the airbox drain so again, no problema. The bowl drain line can hang below because it's sealed by the drain screw...SC

The bowl drain line can hang below because it's sealed by the drain screw...SC

Not quite true. Two passages vent into the bowl drain tube. The first one is the brass tube in the bowl that regulates the upper level of the fuel in the bowl and this passage is always open through the drain tube. A properly adjusted float will always keep the fuel level below the top of the brass tube. Should the float stick, then the brass tube provides an escape passage for the fuel. Otherwise, the fuel would enter the intake manifold/combustion chamber and cause a hydraulic lock. The second passage that drains into the bowl drain line is from the bottom of the bowl and THAT is controlled by the drain screw on the side of the carb.

Not true. Two passages vent into the bowl drain tube. The first one is the brass tube in the bowl that regulates the upper level of the fuel in the bowl and this passage is always open through the drain tube. A properly adjusted float will always keep the fuel level below the top of the brass tube. Should the float stick, then the brass tube provides an escape passage for the fuel. Otherwise, the fuel would enter the intake manifold/combustion chamber and cause a hydraulic lock. The second passage that drains into the bowl drain line is from the bottom of the bowl and THAT is controlled by the drain screw on the side of the carb.

I forgot about the little overflow tube, my bad.:thumbsup:

I should have remembered too, 'cuz my float got stuck and I was hemorrhaging gas a couple of years ago. I've forgotten more than I know...I'm getting old...SC

Sorry to jack the thread but I have a question. 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??

My 07 is brand new. Its never been ridden (long story) & has sat in a heated garage. The fuel that is used is top notch high octane stuff that i have used for years with zero problems. However my choke is blocked and needs stripped out cleaned and or replaced. According to to my local yamaha tech, the fuel has degraded / vapourised leaving a furred or varnished carb. This might require the choke to be cleaned or worse case scenario the carb needs cleaned / rebuilt. Clearly something is not right.

No inline fuel filter!

There is and always has been a very fine and very thin layer of dust behind the filter. Yes, the filter cage hole is plugged.

I just can't imagine that much dirt in the carb!

That is not normal and should not be there with a properly oiled and installed airfilter. The very fine layer of dust in your airboot is just a very very small percentage of the dust that has passed through (around?) the filter. The majority of that dust has gone into your carburetor and is most likely the cause of your buildup on the slide.

How often do you change your filter? Remember that even a clean filter will not filter well if it has been awhile since it was oiled as the oil will eventually dry out to the point that fine dirt particles will no longer stick to it.

If the issue were dirt/dust entering through the vent tubes I don't think you would see a buildup that high in the carb...just down in the float bowl.

Hey guys,

My bike is getting that fine dust past the filter also. I am pretty sure i just figured it out. Remove the filter from the cage and the look at the fit of the cage to the airbox. The rim of th cage does not seat all the way! it is not full pinching the edge of the filter to seal the edge!!!!!! I believe the top of the center post of the cage guide needs to be ground down so the cage can full seal the filter. PLEASE CHIME IN IF ANYONE AGREES OR HAS SEEN THIS BEFORE!!! I think this is recall material.

PS I already got a replacement cage with no freaking hole in it.

Remove the filter from the cage and the look at the fit of the cage to the airbox. The rim of th cage does not seat all the way!

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:

I think this is the problem why these bike suck dirt. THIS IS A LAME PROBLEM. Its a sweet bike and then the idiots try to save money by using a cage that kinda fits. I am going to the dealer. I am pissed!

The part numbers of the air filter cage (aka "Guide") and the cage holder (aka "Guide Holder") for the 07 WR450F and the 07 YZ450F are different.

I suspected that maybe they put a YZ part in the WR or vice-versa. :thumbsup:

Yes I agree. I am really hoping it is a parts mix up on Yama's end. If it is there will be a lot more leverage to get things fixed.

Either way someone dropped the ball big time at Yamaha.

Will the YZ cage even fit into the WR airbox? I thought the WR cage/airbox was flattened out on top compared to the YZ...

Has anyone tried installing the filter without the cage? It seems like the filter sealing surface should be enough. :thumbsup:

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