Have done a couple of dusty trials lately and have noticed very fine dust in the carb throat. Am I under oiling the filter or is this normal. Thanks.

Perhaps your filter isn't sealing fully (?)

Ideally you don't want to see any dirt past the filter. In my opinion you can never really over-oil a filter, since any that isn't held by the foam is just going to drip out into the airbox anyway.

I see you've got a GG, so I'd say make sure when you're installing the filter, it's seated all the way around the cage against the air filter housing, and don't be shy screwing it down. You want the cage to fully compress the foam and seal it tightly against the inlet.

Double check your airbox/carb boot is tight and correctly seated.

Even the best filters are going to let a very small amount in however if the filter is correctly oiled you shouldn't see any dust after a single event.  I could see where after a great deal of riding in dusty conditions you might start to see something maybe... 

I have 3 different bikes I have to do, my daughters Beta 80, my wife's Gas Gas 125, and my Montesa 4RT and haven't ever had any issues like this unless I didn't seat the filter correctly.  

As for oil amount on the filter... I soak the filter completely in the filter oil (don't use the spray on stuff), once soaked I then squeeze out the extra.  When I am done I let the filter sit tell it gets slightly tacky so if touched it will create small strings of filter oil when pulling your finger away from it.  

If you do this and then install it with zero gaps you shouldn't have any issues with the filter letting dust past and shouldn't have any issues with over fueling unless you build up to much dust on the outside of the filter... 

 

Dust? I guess you don't live in the UK. Additionaly to the other advice, try a new filter and check all airbox joints. 

 

Ideally dust should not get past the filter so the above is relevant, however I also smear the inner surface of the airbox with a layer of grease which helps to trap any dust heading towards the engine, especially the entrance to the carb boot.

If it gets further than this increased engine wear will occur.

Edited April 26, 20179 yr by mattylad

Agree with all the above, well used filters can get a bit slack where the cage pushes against the airbox and it can be possible for a gap to form. While you can usually get away with riding a couple of times on one oiled filter during the winter when the mud is clumpier, when its dusty i always make sure to have a clean filter on each outing

Thanks for the replies. I'll be oiling a little more now. Think all other issues are correct on my bike.

On ‎4‎/‎26‎/‎2017 at 6:07 AM, anotherfive said:

Thanks for the replies. I'll be oiling a little more now. Think all other issues are correct on my bike.

I also have a GasGas - and I've found that its possible to mis-align the rubber air box boot with the carb inlet, such that the doughnut shaped spacer gets dislodged, and a gap opens up and allow dusty air to get into the carb through this gap.  I've seen posts about this online somewhere too. 

It's possible, but you have to really not be paying attention, on top of not checking that it's back together correctly after assembling, which you always need to do. Ask me how I know... 

The carbs have small vents to allow air into the bowl as petrol goes out.  Most bikes just seem to have a small length of hose on them.

On enduro bike we put filters there to stop dust from being sucked in.