Not sure if any other solutions for this, but I cut off some "wire" from a metal clothes hanger, a little wider than the prefilter (and internal snorkel opening), and shoved it through the prefilter sideways about 1/3 from the end. Works peachy
GREAT IDEA!! I'm going to try this! The course foam prefilter cylinders are great at keep the large particulate out of the airbox: leaves, bugs, cottonwood tree seeds (the puffy floaty kind), etc... The cottonwood seed is extremely annoying this time of year in MN. It'll fill up your airbox pretty quick!
I read this thread with interest. I will most likely continue to use the OEM paper filters, but will in future grease them up before dropping them in. Not so much for sealing issues, but for potentially helping to keep dirt/sand/small pebbles/bug parts from falling down into the airbox when pulling out the filter. This crud seems to collect around the edges of the filter and no matter how slow and careful I am, some always ends up down in there. With the grease up around the filter edges, I should be able to just wipe up around there and save myself some fugitive dirt anxiety. One other thing - any reason not to put a thin layer of oiled foam right on top of the OEM filter? (Kind of like a pre-filter) I've got some nice fuzzy foam from another air filter I thought I could trim to fit and then lay on top. -- dbh
Yep, found a nice nest of cottonwood seeds hanging onto the prefilters the other day. Remember riding through the "summer snowstorm" and thinking, glad I have a full face on and not sucking all that in and choking.
No reason you can't lay a piece of oiled foam on top of the OEM filter in the airbox. It might, keyword might, restrict airflow a hair and richen things up air/fuel mixture wise, but nothing the bike's computer won't readjust for. I thought of doing this the other day too. I bought two green fine sheets of bulk UNI filter foam to make two air filters for my G450X (worked perfect btw). I might use the extra to cut a flat rectangle that is the same size as the airbox and lay it on top of the UNI filter. Just an idea. But now that I have a way to use the prefilter plugs without them getting sucked into the airbox, I'll probably pass.
...But then you end up with gritty, sandy, buggy grease. IMHO, no net gain. IMHO, don't bother. You could do that if you wanted. My lawn tractor actually has a (non oiled) ~3/8" thick foam pad on top of the paper filter. Especially when mowing through dry grass (when there's more stuff getting blown up into the air), its nice because I can just clean off the foam and not worry about replacing the main filter. IMHO though, unless you REALLY get a bunch of crap on your filter (which I can't see happening except in extreme off road or during a few weeks in the spring/pollenating time of year) there's not much point to a prefilter. By design they don't actually filter out small particulate, and in the end they're just another thing to clean. I also really don't like the idea of plugging up the relatively small diameter intake ducts on the GS. If one really needs a pre filter because of excessive large airborne schmutz, the two intake ducts are going to get choked up pretty quickly. Really, a layer of foam over the entire area of the main filter element makes the most sense. Some foam air filters are "two stage" for this very reason...coarse filtering on the outside to keep the large particles from clogging the filtering, then fine filtering on the inside to keep the small particulates from getting into the engine.
I've always greased the lip of my air filters and it has never caused an issue. In fact it keeps the particulate around the filter hole from dropping down into the air box when swapping filters (I have two Uni NU7308's. I keep one clean and freshly oiled and one is in the bike). Regarding the course foam cylindrical plugs.... They do not 'plug' the snorkel intakes. Even though they're called plugs, they don't technically plug the snorkel. When so and so at Uni and I were talking about the foam cylinder idea, we made sure that the diameter of the plug was just a hair smaller than the snorkel opening. This in turn makes it easy for the cylinders to get blown into the airbox by wind at highway speeds, but it also makes it so the course foam remains porous and truly 'open-cell' as to not hinder airflow in any way. Point being, the cylinder plug foam is so course or 'open' that airflow is virtually unrestricted. Using the course foam plugs would not hinder airflow any worse than laying a rectangle of flat course foam on top of the filter. And the way the plugs sit in the snorkel, they sit out towards out almost flush with the outer end of the snorkel, making it virtually impossible for particulate to build up and plug things up. In certain areas of the world where large air particulate does not exist regularly: San Jose, or any other 'San', 'Las, or 'Los' areas, pre-filtering with course foam for large particulates may not be needed. But here in MN and a lot of other northern states it is a big + to be able to. Take a look at the pics above. This time of year your airbox gets filled up with them.
Have any of you UniFilter guys rejetted your carbs? Apparently it's reccomended by Uni in the FAQ.My F8 is due a service and I'd decided to go over to the Uni foam air filter but if I have to piss about rejetting carbs I'll not bother... is it really that necessary???
LMAO... I've just remembered the F800GS is fuel injected so it doesn't have carbs! Cheers, that means I don't have to worry about it then. Obviously I'm not that mechanically minded. That might explain why it hasn't come up in the threads I've read on foam filters.
Yeah, you could have WWRonin on your ass claiming you said some shit you didn't. Consider yourself lucky.
:huh That's awesome. I just stumbled across this little gem today. I got insulted in a thread where I haven't even posted a single reply. Thanks a lot Griz. Nice to see you are maintaining such an even keel. Dan
Is there a filter skin available? On these long rides TAT, GDR its nice to pull and replace a skin without having to clean dry and oil the filter.
The filter is such that I can't see how one would work. You could try a piece of furnace filter media or something similar as a pre-filter laid over the stock paper. The foam filter I have filters through the smaller inner diameter and there's not much of a lip to stretch anything around the base to make it work reliably. YMMV
Been there and done that. Will not go and use any filter that requires oil again IF there is a mass airflow sensor that uses light bouncing off of a piece of metal. The oil can get in and cover the metal rendering it inoperable (limp mode). You may get lucky and be able to clean it with some good electronics cleaner, but not for me - not worth the hassle (or the shuddering or the loss of power to save $50-$100 over 3 years versus the price of replacement regular filters). I really am skeptical of the need to use oil on a filter unless we're talking about dirt biking in some horrendously dusty conditions. Even then, you have to be really careful about how much oil you use. Those filters look like things I've used in fish tanks. http://www.thatpetplace.com/filter-foam I suppose you can cram some foam down the snorkels for $4 which can sub pretty well as a pre-filter.
I read that the BMC filter designed for the HP2 will fit the F800GS. So, I reasoned that the K&N equivalent should fit too. So I took the plunge and ordered one to try. US$90 on ebay. (Including delivery to New Zealand) http://www.knfilters.com/search/product.aspx?Prod=BM-1208 Well it almost fits. I had to cut a small section off on corner. At the pointy end, not the sealing end. About 40x 24x24mm (1.5inch by 1 inch by 1 inch. For you non-metric folk) It is a very small part of the filter. I then sealed up the gap with liquid hot glue and a small piece of plastic. This leaves a huge amount of surface area. 3 or 4 times the standard K&N filter. And it can still be cleaned as normal. I used by GS-911 to reset the engine calibration first. So, how does it go? Well the Mrs was on the back so I did not get much chance to open it up. But it felt good off the throttle. I will give it a try on my own this weekend. The standard rider report in these cases seems to be "better low to mid range response, a nicer intake noise" and other similar unscientific statements to support their impulsive purchase. So don't expect anything too far from this from me. But it is fun to furkle and I now have a nice re-useable air filter. If I ever open up the exhaust, then it may even go a bit better. After my 650 it goes pretty good, but certainly does not have the instant grunt of my old R1200GS. have fun
Did you remap for more fuel? The bike already runs lean from the factory, opening the air intake and the exhaust without getting more fuel in to the motor somehow is what makes me think twice about this. Also, can you put up a picture of how the HP2 filter allows for a bigger surface area? The air box is drawing through the two feeder tubes and then on to the surface of the air filter which is limited to the physical opening of the air chamber. Do you mean the filter is deeper? If so, it will offer more filtration, but how will it offer more air flow? Just curious. How about a picture? I found the lip was too narrow on the K and N filter that fits the GS1200 to run it in the airbox of the 800/650.
I "think" the mapping can accommodate some mods in the intake and exhaust. The mapping is in the form of mathematical logarithms stored in the ECU. Which map, is determined by sensors that determine rpm, oil temp, air pressure and air temp. The bike runs in closed loop or a predetermined map at steady state throttle at Stoich (14.7afr). A change in the throttle position causes the bike to go into open loop and allows the sensors to determine the proper afr for the conditions and it will pick an AFR other than stoich. The oxygen sensor detects the change in AFR and return the ecu to stoich when conditions allow it. Opening up the intake and exhaust will be detected by the air pressure sensor and if the ECU has a wide range of logarithms it should account for the change. The ECU should adjust to changes and pick another base logarithm that provides stoich. How much air reaches the engine really depends on the area of the throttle bodies and vacuum created by the piston on the intake stroke. I doubt there is much if any "ram effect" The richest mixture I have seen on a dyno posted was 14.4 afr. What I don't know is whether that is the richest map the ECU has or if that was just what the ECU determined appropriate. If you are not getting any pinging on acceleration(open loop), you should be fine. The ECU will accommodate more air at steady state throttle (closed loop) Whether the filters do anything at all would require the ability to measure air flow under a variety of conditions out of the air box.
yea, maybe take a picture next time I have the thing apart. Regarding the surface area. This is the surface area of the actual filter element. The bigger the surface area, the more air can flow. It does not mean better filtration. (Though arguably the same amount of air would be traveling through more dust attracting oil) The standard K&N for this bike is the same surface area as the opening. (Ignoring the fluting) The BM-1208 filter has much more filter area as it is deeper and the filter material is around the sides. It is like comparing the lid of a jar with the sides. As I understand it two areas of restriction to airflow are: 1 - the size of the hole the air comes through. and 2 - the surface area of filter the air has to go through. As pointed out above, I can only guess at which is the most restrictive aspect without actually testing the air flow. With no air filter then the restriction is mainly down to the size of the openings in the inlet snorkel. If the filter allows less air through than that, then going to a less restrictive air filter would potentially allow more airflow. The team building the rally bike (see other post) had "good results" by installing the BMC filter along with opening up the exhaust and the inlet. I do not know how scientific that is. But it is worth a try. My goal was to install a re-useable filter as I like them. I went for the bigger airfilter just to give it a go. Nothing particularly scientific about it. Also, for anyone looking to work on the inlet and exhaust, I have at least shown that the K&N bm-1208 can be modified to fit. As for the ECU. I used the GS-911 to "Reset adaptation values completely" so the ECU gets to relearn. I will take it for a good ride this weekend and check the ECU with the GS-911 after the ride. The instruction suggest looking at the real time value of the lambda sensor which will show if the ECU is handling the airflow change. (http://www.hexcode.co.za/products/g...er-manual/the-gs-911-application/using-gs-911) Thanks.