Beta Riders Club Discussion Forum

This morning when I took the dirt air filter out after last weekends dusty ride, I noticed there was water in the bottom of the airbox and the bottom lip of the air filter was soaked.





Now, the design of the access to the airbox and filter means that the effective "wading depth" of the bike is always going to be limited as it is easy for water to get into the airbox through the bottom left side of the airbox side cover. And because the water is so low down I ordinarily would not be concerned about the engine sucking in water... until I inspected the dirty air filter.


The wet bit of the filter that was resting in the water accumulated in the airbox is shown in the blue ellipse. But also notice the particularly dirty bit of filter in the red ellipse. This is presumably the part of the air filter working hardest (i.e. deals with the most air being sucked in) and hence has had to do most of the filtering work leaving more dust residue there than anywhere else. To me, it seems to be sucking q lot of air from lower down on the filter, and so my logic says that if water gets in at the bottom of the filter is stands a better than average chance of being sucked into the engine. Am I right?

After cleaning the water out I noticed what looks like a drain plug of sorts in the bottom of the airbox (red arrow). I took a look in the workshop and owners manuals but didn't see either of them mention it at all, much less detailing whether it is a drain plug or not.


So, now I'm not sure whether to try removing the plug (if that is what it is) to ensure that I do not get water accumulating in the bottom of the box again, or whether it would be worth drilling a small drain hole in the lowest part of the box. Either way, by allowing water out, it just as easily lets water into the airbox from the bottom. But now that I am aware of the fact that the bike cannot (or should not) wade too deep I am unlikely to be pushing my luck with deep crossings anyway, and water is more likely to leak in the side of the airbox lid (side panel) than a hole in the bottom of the box.

I also noticed that there was a bit of dust on the inside of the airbox after the air has passed the filter (yellow arrow) which is obviously not good. It was a fresh clean filter at the start of the dusty ride, and although there was a lot of dust I would not have thought I should expect much (if any) dust to be sucked in past the filter. When I look at the size of the filter, with the amount of surface area that is NOT caked in dust, there should be more than enough clean filter to stop dust. I reckon the dust that did make it past the filter was sucked through the small bit of filter that is dirtiest - there must have been enough of a vacuum force to suck dust in through there (as the path of least resistance) rather than that bit of filter getting clogged up enough to force air to be draw through other bits of the filter.

When I compare it to my dirty KLX filter the KLX one is pretty much uniformly dirty - but that filter sits centrally over the carb inlet so it is logical that the air is sucked in uniformly across the surface of the filter by a pretty consistent vacuum across the whole filter surface. The Beta airbox seems to wrap around the rear shock more and so seems to "focus" the draw onto a smaller section of the filter. The question is, what can I do about it? I would prefer to do something about it than just accept that it is inevitable that I will end up dusting my motor on a dusty ride. Any suggestions? I wonder whether putting a strip of duct tape across the bottom of the filter opening would help? It would, at a minimum, reduce the likelihood of water being sucked in from the bottom of the filter if I do a water crossing a bit deeper than I should. But would is change the air flow enough to force air to be sucked in over a great surface area of the filter? Would it make things worse? Man, I wish I knew more about fluid-dynamics and had the equipment needed to play with it more.

Yep, that's a drain plug. Squeeze the outside of it like you were milking a cow and the water will flow out. It seems to me that the rubber is slightly to stiff - it should open up under the weight of the water in the little stand pipe. While you have the airbox cover off you should check and see if you've got little pebbles or dirt clods in the drain - they can enter from up near the grab handles.

See "Drain Tube" thread from Sept 19th. Lots on this subject.

Make sure to grease the filter lip.

Actra,

Airbox on the Beta needs a little more care and attention then on other bikes.
As others have said in different topics, you can get everything from pebbles to grass and small branches inside it.
I check mine after every ride, and clean the debris or dust.
I clean the filter every 200-300km. I never had it as dirty as yours, but those skid marks are typical.

Something like this may help:

http://www.ktmforum.co.uk/off-road-enduro/27007-preparing-08-450r-like-knighters.html

If you ride in very dusty conditions, you may consider filter skins or over filters. I've read that some people use women's stockings.

You could also test one of these filters for us.
https://funnelwebfilter.com.au/product/beta/

I've read that some people use women's stockings.

Just be careful you don't snag them on the buckles when you put your boots on......

That's an interesting filter. More volume. Wonder if it would hold up to No Toil oil and cleaner? They do make one for Beta 2t. I used pre filters in the past to stop dust and they work. But don't think they would work well to stop water. Mud yes. Maybe just duct tape the seams of the sidecovers if U know of watercrossings are ahead.

Hey here, I smear grease all over the inside of the intake boot to catch some of the dust that gets through the filter skin and the air filter. Cheers Richard

Why not just tape up the seams of the air box to seal it up? Any reason not to do this?

flybars wrote:That's an interesting filter. More volume.

The filter is interesting at first glance, but I don't like it. The draw of air through the filter depends on what the engine is drawing. The air will flow though the path of least resistance, so the majority of the air will flow through the areas without points first as there is the least amount of foam (resistance) to travel through. When that area gets dirty enough to increase the resistance, the air will start to flow through areas with a little more foam until the filter gets dirty enough that the air is flowing through the little points of the filter. At that point, the filter will be working like your stock filter with air flowing through all of the filter. In reality, this design effectively DECREASES the usable surface area of the filter until it gets dirty enough while increasing the cost of the filter.

If the little spikes were all duplicated with little holes on the inside of the filter so the thickness that the air needs to travel through was pretty much the same everywhere, than this filter would increase filter surface area and might be worth the extra money.

My 2 cents.