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My bike currently uses no oil, considering the conditions under which the maintenance was undertaken in that particular instance most likely that dust got on there from the removal process. I believe rather than spotty oiling the appearance is due to the varying thickness of the dust. I could be wrong it was 2 years ago. Good points to consider though as I am about due to clean the air filter again so will pay particular attention to the oiling.
 

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For the KLR application, I remember reading some very in-depth articles on different setups and this included air filters, even similar styles. The K&N did not perform as well as the UNI and Twin-Air filters, all 3 of which were DYNO'd and analyzed by a couple different guys (they were pushing insane HP, very min-max type stuff). I forgot their names, but it's all out here on the 'net.

That said, I have a similar style of filter on my pickup and when cleaning, make sure it's washed from the inside out...do not push the dirt inward through the filter material with water. It also says don't spray it, just use running water from a faucet going inside to outside and RE-OIL it.

I do believe an atomized mineral oil works, though it recommends the re-charging kit for mine as well. There's a certain amount, but you can kinda eyeball it if spraying just mist each section carefully and don't get too much on there. Really only requires an once or two total. Make sure it's misting not drenching lol.

Caveat: Usually, foam filters for KLR are recommended to be oiled by foam/dunking and rolled out (not wringed out), IIRC. That said, I don't have direct experience w/ the K&N filter for KLR, so I don't know about their procedure or recommendations. It sure looks just like an intake filter I use on my truck, though. In which case, flattening the filter is a big "no no." I would imagine it being a spray-to-oil type.
 

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I found this graph on the internet and it tends to support many folks' opinion about the poor efficiency of K&N filters. Notably, the UNI filter was not much better in this particular test. But it should also be noted that the testing was performed with automotive air filters, not MC air filters.

Jason

View attachment 26885
K&N Air Filter Review - Debunking the Myths (and why OEM is better).
In this case efficiency refers to the filters' ability to keep dirt out of the engine. If maximum airflow is important to you, then, obviously, no filter is the way to go.
If keeping dirt out of the engine is more important, then I'm not too sure that UNI is the best filter for this application, but it's much better than no filter.

Jason
 

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I'm pretty certain that 'Amsoil' thur 'AC Delco' in that supplied graph are paper media air filters. Someone may correct me if I am mistaken.

I still like using the OEM fine pored Foam Air filter with SAE40 engine oil. TwinAir works great with SAE 40 oil also.

The coarser foam filters like Uni-Filter really need the sticky foam air filter oils, because their coarser foam allows TOO Much of thinner oils like SAE40 to drain out of the foam!
 

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I'm pretty certain that 'Amsoil' thur 'AC Delco' in that supplied graph are paper media air filters. Someone may correct me if I am mistaken.

I still like using the OEM fine pored Foam Air filter with SAE40 engine oil. TwinAir works great with SAE 40 oil also.

The coarser foam filters like Uni-Filter really need the sticky foam air filter oils, because their coarser foam allows TOO Much of thinner oils like SAE40 to drain out of the foam!
Yes, I'm thinking that AMSOIL "thru" AC Delco are paper filters, too.
Maximum air flow and maximum filtration tend to be mutually exclusive attributes. I believe that the coarser the filter media, the more air and dust can pass through. So, you may realize a performance gain if tuned for the increased air flow with a coarser filter, but at the expense of more dust entering the engine.

Jason
 

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Yes, we are comparing apples to oranges with that paper filter chart; that said, every test I've seen has shown the K&N to let more dust through than an oiled foam filter. The Uni is coarser than stock but comparable to several "real dirtbike" filters I've used and I think it filters well if used properly with real filter oil. YMMV

Dave
 

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Discussion Starter #30
Finally had some time last night to clean, re-oil, and re-install the K&N air filter originally installed by the PO.

Short story: wow! What a difference a clean air filter makes!

I was happy with the bike before, but the butt-dynometer showed significant performance gains. Before, it would pull nicely through about 4,500 RPM. With a clean filter, it was ripping up to 6,000 RPM or so.

I ordered a new air filter holder and UNI filter at the same time I ordered the K&N cleaning kit. I'm going to stick with the K&N through the next tank or two of gas, then install the UNI and see what difference it makes.

For the interested, here are a couple pictures of the airbox and filter "cleaned", re-oiled, and installed. (I say "cleaned" because although it was definitely cleaner than before, it doesn't look anywhere close to new, out-of-the-box clean.)

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Additional info on Uni and K&N filters and airbox mods on the KLR for any that haven't seen it before.

There is only about 2 cfm differance from the best filter (UNI), to the worst (K&N). With a modified airbox, that differance grows to 9 cfm.



Here is the flow chart:


Completely stock - 64.8cfm

Same - Remove snorkle - 74cfm

Same - With UNI filter - 76.2cfm

Same - Remove screen - 78.6cfm

Same - Small "L" cut - 85.1cfm

Same - Large "L" cut, open snorkle area further - 92.4

All at 2" of water, tested at 1 1/2" and 3" and averaged to 2"


To answer the larger question, how much air can the KLR really use? A stock KLR about 70-80cfm. With a good pipe about 75-90cfm. A modified motor about 90-100cfm. Having a bit more capacity than you you need will not hurt anything. The effects are not linear though. Going from 65cfm to 75cfm you will likely notice, but going from 75 to 85 cfm you likely won't.


Most of us try to get to at least 85CFM using the snorkle removal, L-mod or 4 - 1" holes and Unifilter (I don't recommend removing the backfire screen). Anything less than 80 would appear to hamper even a bone stock KLR. The 9CFM difference between a Uni and K&N is huge in this context and is due to the metal end plate design, not the media or oil.

Dave
 

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Additional info on Uni and K&N filters and airbox mods on the KLR for any that haven't seen it before.

There is only about 2 cfm differance from the best filter (UNI), to the worst (K&N). With a modified airbox, that differance grows to 9 cfm.



Here is the flow chart:


Completely stock - 64.8cfm

Same - Remove snorkle - 74cfm

Same - With UNI filter - 76.2cfm

Same - Remove screen - 78.6cfm

Same - Small "L" cut - 85.1cfm

Same - Large "L" cut, open snorkle area further - 92.4

All at 2" of water, tested at 1 1/2" and 3" and averaged to 2"


To answer the larger question, how much air can the KLR really use? A stock KLR about 70-80cfm. With a good pipe about 75-90cfm. A modified motor about 90-100cfm. Having a bit more capacity than you you need will not hurt anything. The effects are not linear though. Going from 65cfm to 75cfm you will likely notice, but going from 75 to 85 cfm you likely won't.


Most of us try to get to at least 85CFM using the snorkle removal, L-mod or 4 - 1" holes and Unifilter (I don't recommend removing the backfire screen). Anything less than 80 would appear to hamper even a bone stock KLR. The 9CFM difference between a Uni and K&N is huge in this context and is due to the metal end plate design, not the media or oil.

Dave
Very useful info. Presuming mine has the snorkel, it will be coming out and the mini-UNI vents later down the road w/ exhaust swap to Big Gun.

Q: With modified L cuts and half-open doors and de-snorkels, etc. is there no worry of off-road mud and debris or even just water entering?

This has always semi-boggled me...


Sent from my iPhone using Tapatalk
 

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Very useful info. Presuming mine has the snorkel, it will be coming out and the mini-UNI vents later down the road w/ exhaust swap to Big Gun.

Q: With modified L cuts and half-open doors and de-snorkels, etc. is there no worry of off-road mud and debris or even just water entering?

This has always semi-boggled me...


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The L cut or 4-1" holes in the top are higher than the factory opening so there is no additional risk of water ingress. The snorkle intake is the same height with or without the snorkle present so no difference in water ingress there either. I don't recommend any other mods, including modifying or removing the door. As far as mud and debris goes - the openings are still under the seat and sideplates and are adequately protected from such things.

I strongly recommend avoiding the little 1" filters that are available to pop in the holes; all they do is add restriction and maintenance and are counterproductive to increasing the airflow - the primary filter is all that is required.

For the record, the vast majority of the 41 motocycles I've owned were offroad racing bikes and such bikes have massive openings in the airbox and are used in far harsher environments than most KLR's. My KTM airbox didn't even have a left side or top, just the side panel and seat covered the openings.

cheers,
Dave
 

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^^^^^^
 

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Regarding the screen, I pulled off my Uni filter to check inside. I couldn’t get inside the clean side of the air box because the screen was in the way. I didn’t know that was a “feature.” Mine was about 50% blocked by some kind of waxy deposits, presumably from oil deposits from the filter. About 15 minutes of scrubbing with a parts brush and kerosene, then more with carb cleaner, got it off. I’m thinking of cutting it out completely. Any pros or cons?
 

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Regarding the screen, I pulled off my Uni filter to check inside. I couldn’t get inside the clean side of the air box because the screen was in the way. I didn’t know that was a “feature.” Mine was about 50% blocked by some kind of waxy deposits, presumably from oil deposits from the filter. About 15 minutes of scrubbing with a parts brush and kerosene, then more with carb cleaner, got it off. I’m thinking of cutting it out completely. Any pros or cons?
The 'back-fire' flame arrestor screen is there for a good reason on 4 stroke engines. Do as you wish.
Did you drain the cleaner from the clean side Air Box drain hose? Hopefully, the clean side drain hose still has a cap?
 

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Discussion Starter #39
Thanks for the info about the effect of the different filters and airbox mods on the CFM. Great stuff! Glad I found this forum!

If the UNI filter provides an additional 9CFM, should I expect any carb issues like backfires, running lean, hard to start, ...?
 

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Paul, the drain hose and cap from the clean side of the air box were missing. I put a clear tygon hose on it with a plug. The fact it was missing when I bought the bike may explain why I have such high oil consumption (engine dusted). And the PO did a lot of dirt riding.
If the screen only adds 2.5 cfm of airflow, I’ll leave it alone for now. Maybe when I upgrade to a 692 this winter, I’ll remove it then.

But to go back to the problem of waxy crud on the screen, have you or others experienced this too?
 
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