I am wondering your experience with uni foam filter on airheads. I am not too keen on paper in water areas and high dust with off road riding so I picked up a Uni foam filter to give it a go, using PJ foam filter oil tacky spray on top side. Just installed, it was around $30.00 and reusable with a solvent wash and rinse. Anyone have good or bad experiences with this arrangement? This is for my r80g/s
Foam is a great filter IF you service them. Every single airhead I have ever serviced with a foam filter had a filter than needed to cleaned and oiled a long time before I got there. They don't filter much at all dry. I have a lot of experience with foam filters in dirt bikes. I don't want to mess with my filter that much in a street bike. I use K+N with great results. They filter much better than paper. Yes, I know there are a number of 'scientific' tests that prove K+N's don't filter as well as paper but I have serviced a lot of airheads and from what I see with my own eyes K+N's filter much better. That's why I mention them. I have around 140,000 miles experience with K+N's myself in airheads. Great filters.
I'm happy with mine. I ride off-road more than on and my friend loves to make me eat dust on his stupid orange bike. I do clean it regularly, but that's part of the deal.
I like my UNI filter (KLR) but be sure to use the correct cleaner for the filter, some are not compatible and will dissolve the glue used in the filter construction.
I had one on my bike for 15k. The biggest problem was that it leaked between the air box and the filter it self. I found a lot of dirt in the air box even with the filter proper oiled. If you would like one send them a good original filter and let them make the foam inside the stock plastic outside. On my ST I replaced the filter for an oiled cotton one just like a K&N which filters better than my Uni filter(when oiled ok) Another thing I had with the foam was that lots of water washed the dirt trough the foam which it didn't do with my DNA filter.
To Prutser's comment, I do grease the edge of the filter where it meets the airbox. And, he thinks his bike is a U-boat!
I'm pretty happy with my Uni Filter. They do a good job. But they do need pretty regular servicing. I use 'No Toil' cleaners & filter opil which makes the cleaning reasonably painless. I think Phreaky Phil has his Uni Filter set up with pre-filters, & that makes them even better. I need to investigate doing that myself.
The edge of my uni filter was to soft. The rubber was so flexible that it was sucked into the air box. For the rest I think they work fine...most of the time I did find a way to seal the edges. Just used an old stock filter and mounted the uni filter on the top. That way it sealed really good but you need to lengthen the spring clips that hold the top cover.
I just figured all the dirt I saw in the airboxes I serviced with Uni Foam filters was for the filter being bone dry but . . . . That's another reason why I like K+N's. If you modify the filter body to fit right, the filter body seals real good against the box. It's made out of about the perfect stuff I guess. Soft but not too soft rubber. What I don't understand is how the stock filters let all the dirt in? Bikes I service with off road miles and stock filters have air boxes full of big chunks of whatever in there. I have seen that play out many times over.
The paper filters When a bit dirty start pulling the dirt right through. I have sealed the filters around the edges for customers with grease and at the next service the grease sealed but the paper allowed a lot of dust downstream. Oiled fabric and foam filters were developed for desert racing where dust was killing bikes with paper filters.
Be careful with No toil cleaners and UNI, sometimes there can be disastrous results. There are a couple threads discussing this issue.
So it seems there is good results IF the filter is maintained. I ride mostly offroad with the Berg and KTM so I am very familiar with maintaining foam filters... I also greased the bottom of the filter for max sealing. One area for improvement they could make is the top interface, the top side seems too soft and the middle gets suck in when the clips are apply, careful installation makes it even. This does not affect the filtering, just a PITA for installation. Thanks for the input, all very helpful.
In my experience, tacky oils shouldn't be used on Uni or any other foam filter. I know firsthand that K & N filter "oil" will clog Unifoam. Makes the filter act much like a mechanical choke. I use regular motor oil on most foam filters squeezing the excess out to get it saturated just right. And naturally K&N spray "oil" on the K&N on my airhead. Which reminds me, its about time to inspect, clean, and repspray that filter. I have experimented with a sheet of Unifoam cut to fit right over the top the K&N in the airhead after reading some of the bad press about K&N filtering ability. I eventually pulled it back out and set it aside. Never really found any dust or dirt on it when I pulled it after a couple thousand miles.
+1 I have always just used straight 30 or 40 weight motor oil on foam filters. That's all they need to work great! K+N's? I have never used anything but K+N oil. Works great! Servicing K+N's? I re-oil them once or twice a year but I think it's really important NOT to clean them every time you oil them. K+N's need to be oiled to filter properly. They filter better dirty. They hold oil better dirty. All that adds up to them working best oiled and dirty. When I service K+N's I hold them upside down and hit them against the wall to knock all the loose dirt and bugs and stuff off of them. I them get a stick and kinda scoop out the bugs that won't come out. I them re-oil them and put them back in. Black with oil and dirt that is all underneath the filter's wire mesh is perfect. I have used two K+N's filters personally. I have never washed either one of them other than knocking loose dirt out of them. So many people wash them too much and and oil them not enough. Nine out of ten photos of K+N's that I see here on ADVR do not have near enough oil on them to filter properly. Some of them right out of pro shops! New K+N's? They need re-oiling more often until they get black with dirt. Check them often and spray more oil on them until they get enough dirt in them to better hold the oil. Then don't wash them! K+N pre-filter? K+N sells them. They are made out of nylon stocking material. They work but I have never had the need for them. The filter itself works almost perfectly. Reading about K+N's on the idiotnet? Most of it is complete BS! The real world and real bikes? There's your answers.
Most people over oil their foam filters, I'm mainly talking about dirt bike filters. They think you have to saturate them and then squeeze out the excess. The right way is to put on just enough so that when you squeeze it, you get a uniform color of oil throughout the filter. Tacky oil works great when you use the right amount, and you can use less of it than regular oil. K&N oil is thin and not intended for anything but fabric. I bought No-Toil when it first came out, should not have, knew better. The bottles sit, dusty, at the back of a shelf. TwinAir filters and oil for all of my dirt bikes since the '70s, and TwinAir oil works well on my Unifilter.
for me..... given that i got 450hrs on my ktm 525 before a refresh was needed and on inspection the bore and piston were in amazing shape, just the bore was simply wore out i will stay with my current tacky oil practices... spray lightly, massage to consistent coverage, greased interface to airbox. i like the tacky as it remains in place where oil will drain, but then again i maintain filters before that is an issue. proof of your practice is how clean air box is at time of maintenance.
Is 450 hours a long time for a KTM.? It equates to about 30,000 miles at road speed. I can't see that sort of bore life as recommendation for a filtering or lubrication system.
I could see how tacky oil for foam filters would be a big plus on street bikes for the oil not separating from the foam as much? But I am just guessing. I have never used it and will most likely never use foam on a street bike for K+N's. Regular motor oil worked just fine for my foam filters in my two stroke dirt bikes. This is the first air filter thread I have ever seen that didn't go down hill fast with googled BS. Knock on wood! It's great when the discussion makes sense to experience. Maybe I spoke too soon!?!
