The 2012 CRF250L thread

[nbrooks]

I did only use one layer of foam. I used Uni Filter part #BF-5 which is rated at 40PPI. Uni Filters most course bulk filter is rated at 30 PPI and most fine is 65 PPI. I am using the 30 PPI foam on all openings on my air box. I popped in 8 Uni Filter box vents, two in the top and six on the cover. I even put a piece of the course foam over my snorkel. Meaning all air entering is going through two filters. Which leaves the question, is 40PPI too coarse to use? Should I just layer a 65 PPI and then put a 30 or 40PPI over it? Just not sure what would be the best balance between low air restriction and best protection. The seat concepts seat is much more comfortable than stock. I did a 145 mile desert ride with the stock seat and I had a hard time sitting down for two days. Same ride with the seat concepts seat and I could sit fine. I guess that's science for you. I did the seat install myself and recommend an air or electric stapler. I used a hand spring loaded stapler and it caused addition work to get the staples to seat all the way in. It's doable with the hand stapler, just made it more difficult.

[Spud Rider]

Originally Posted by nbrooks

...I may be a Noob to this site, but I have had Motorcycles and ATVs for the the past 25 yrs. I always find myself taking things appart to see how they work or to "improve" them . Sometimes it works in my favor and sometimes I end up creating a lot more work for myself. I have put 1000 miles on my CRF in the last two months, mostly riding in the desert of Utah and Arizona. I have really enjoyed the bike and the mods I have made have really opened the bike up. FYI the bulk foam from Uni was about $12 and came with enough foam to cover this filter area about four times, so plenty...

I admire your ingenuity and willingness to modify your bikes in an effort to improve them. I enjoy modifying my motorcycles, also. You did very nice work modifying your air filter.

Originally Posted by Ed@Ford

nbrooks:

Do I assume you have foam of one kind only? Cleaned my KLR Twin Air and my XR400 Uni filters recently, and they have real "fine" foam on the inside, and a more coarse foam kinda like your red stuff on the outside...

Originally Posted by nbrooks

I did only use one layer of foam. I used Uni Filter part #BF-5 which is rated at 40PPI. Uni Filters most course bulk filter is rated at 30 PPI and most fine is 65 PPI. I am using the 30 PPI foam on all openings on my air box. I popped in 8 Uni Filter box vents, two in the top and six on the cover. I even put a piece of the course foam over my snorkel. Meaning all air entering is going through two filters. Which leaves the question, is 40PPI too coarse to use? Should I just layer a 65 PPI and then put a 30 or 40PPI over it? Just not sure what would be the best balance between low air restriction and best protection...

Based upon recent research, I would encourage you to use the finest layer of foam in your air filter to trap the most dirt, and offer the most protection for your engine. I would also install a second layer of the finest foam in the space available on the inside of your air filter.



In addition, I suggest you experiment using pantyhose or filterskins over your modified, foam air filter to screen out the largest dirt particles.

However, unless one is willing to spend $100 for the Best Dual Sport Bikes Uni Air Filter, I am inclined to believe one will get the best engine protection and best air flow by using the stock, paper air filter with the backfire screen removed.



One can buy the stock, paper air filter for $12.40, plus shipping.

http://www.cyclepartsoutlet.com/fich...13&fveh=135195

Therefore, one can buy 8 paper air filters for the price of one Uni Air Filter. The paper air filter for the CRF250L is positioned to face slightly downward, so much of the dirt will fall off this paper filter, rather than adhere to it.



A paper air filter performs very well, unless it gets wet. For this reason paper air filters are used in most heavy construction equipment as well as automobiles. One can also extend the life of a paper air filter by knocking the dirt off it and/or blowing compressed air from the inside surface of the air filter.

Most dirt bikes come equipped with foam air filters because foam will collect a larger volume of dirt and still continue to function under extremely dusty conditions. However, if one doesn't ride under these extreme conditions, I think the stock, paper air filter, with the backfire screen removed, will offer excellent air flow with better protection for the engine.

You might enjoy viewing the following video concerning air filters. However, I disagree with the video's statements regarding paper air filters; paper air filters perform very well in all but the most brutal riding environments. According to Wikipedia:

"Pleated paper filter elements are the nearly exclusive choice for automobile engine air cleaners, because they are efficient, easy to service, and cost-effective. The "paper" term is somewhat misleading, as the filter media are considerably different from papers used for writing or packaging, etc. There is a persistent belief amongst tuners, fomented by advertising for aftermarket non-paper replacement filters, that paper filters flow poorly and thus restrict engine performance. In fact, as long as a pleated-paper filter is sized appropriately for the airflow volumes encountered in a particular application, such filters present only trivial restriction to flow until the filter has become significantly clogged with dirt. Construction equipment engines also use this."


http://en.wikipedia.org/wiki/Air_filter




Spud

[lstehbens]

I had a test ride on one of these little babies today. Gotta say I walked away quite impressed. Felt pretty happy around 100km/h and a bit over. If I have to give back my current bike to its proper owner it's on the short list. Cheap and cheerful commuter, seat wasn't too bad for stock. Found the clutch/shifter nice and gearbox felt good.

Any news on when a bigger tank is coming out yet? How many km/s (or miles) are people getting to a tank now that some people's bike are starting to get run in?

[Ed@Ford]

Spud Rider:

All this paper filter hoo-rah reminds some contract work I did about 12 years ago for Fram. We set up an engine provided by them that was equipped with a full induction system and had paper filters. We baselined the wide open throttle (WOT) engine power with clean filters. Then we tested the engine with filters that were clogged with the "calibrated" dirt used to measure air filter collection efficiency. These filters had been tested on a separate air flow stand to measure the level of flow lost with sucessively higher quantities of dirt. An air filter they considered totally clogged and unacceptable for use was run on the engine. They were amazed that the engine lost less than 10% power at WOT. I think the engine was a 2 liter Honda Civic. Then we took metal plates to close off the clean filter. To get to 10% power loss, the inlet side of the paper filter was about 75% covered over. In subsequent "off the record" discussions I asked them about oiled gauze filters like K&N. They only said that the collection efficiency was AWFUL, and that there were some green colored oiled gauze filters that were WAAAY better, but restriction was about the same as paper. They were led to the realization that oiled gauze type filters were not good enough for them to market. They had no experience with oiled foam like Uni and TwinAir.

[G19Tony]

Originally Posted by mxbundy

Does look good, even if I do say so myself!!

Bundy

Could I request that for my seat when I order it Bundy?

Very nice looking. I'm going to try and make an overnight trip to the Slabs next month. It's a 325 mile run from Vegas.

[strongbad]

The OEM filter isn't paper. It's oil-impregnated paper. You'd be very hard pressed to find a more efficient filter.

[Ed@Ford]

Originally Posted by strongbad

The OEM filter isn't paper. It's oil-impregnated paper. You'd be very hard pressed to find a more efficient filter.

Is there a cleaning process described in the service manual, or owners manual, or is it like a car....just replace on a schedule....

[falconati]

Can I ask how folks on ADV are using this bike? My parents bought some farm property and I was thinking that this bike might be great fun on their property. There's also a gravel road from the property into 'town,' and then about 10 miles of highway to get to a larger city. So I'd like a plateable bike that is good fun off-road (nothing super serious), on gravel, and short stints on the highway. Thoughts?

[ramz]

Search youtube.com for CRF250L and see it LIVE; roads, 4WD, trails, bogs. You might even run across my no-frills movie:
http://www.youtube.com/watch?v=5xKnI...ature=youtu.be

[Spud Rider]

Originally Posted by Ed@Ford

Spud Rider:

All this paper filter hoo-rah reminds some contract work I did about 12 years ago for Fram. We set up an engine provided by them that was equipped with a full induction system and had paper filters. We baselined the wide open throttle (WOT) engine power with clean filters. Then we tested the engine with filters that were clogged with the "calibrated" dirt used to measure air filter collection efficiency. These filters had been tested on a separate air flow stand to measure the level of flow lost with sucessively higher quantities of dirt. An air filter they considered totally clogged and unacceptable for use was run on the engine. They were amazed that the engine lost less than 10% power at WOT. I think the engine was a 2 liter Honda Civic. Then we took metal plates to close off the clean filter. To get to 10% power loss, the inlet side of the paper filter was about 75% covered over. In subsequent "off the record" discussions I asked them about oiled gauze filters like K&N. They only said that the collection efficiency was AWFUL, and that there were some green colored oiled gauze filters that were WAAAY better, but restriction was about the same as paper. They were led to the realization that oiled gauze type filters were not good enough for them to market. They had no experience with oiled foam like Uni and TwinAir.

Thank you for posting the good information, Ed.

As your experience indicates, paper air filters not only block dirt very well, they also allow excellent airflow. In addition, the paper air filter for the CRF250L only costs $12.40, whereas the paper air filter for my XR650L costs $37.96.

I decided to switch to Uni, foam air filters on my Honda XR650L for the following reasons.

1) The XR650L, paper air filters are far more expensive than Uni Air Filters.
2) The XR650L, paper air filters have a very restrictive backfire screen, which is virtually impossible to remove.
3) The XR650L, paper air filters have much less surface area than the Uni Air Filters
4) I frequently ride in very dusty environments.
5) I believed the hype that paper air filters restrict airflow more than foam air filters.

I first employed BelRay filter oil on my Uni Air Filters, and I discovered how goopy the petroleum filter oils can be. The BelRay filter oil stopped the dirt, but it was so thick it also stopped a lot of the air flow. After switching to No-Toil Evolution Filter Oil, I noticed increased air flow through the air box, and increased power from my engine. The No-Toil filter oil is vegetable based, and much less goopy than petroleum filter oils. The No-Toil Evolution Filter Oil is very tacky, and stops all the dirt. However, the No-Toil Filter Oil is very easy to apply, and distributes evenly throughout my Uni air filters. Combined with a larger surface area and no restrictive backfire screen, I am getting excellent air flow with my Uni Air Filters when they are coated with No-Toil Evolution Filter Oil.

In contrast to my XR650L, the CRF250L has an inexpensive, paper air filter from which the backfire screen is easily removed. The air filter of the CRF250L is also positioned to face slightly downward, which will also help it to shed dirt. Therefore, I think the paper air filter in the CRF250L is very efficient, effective, and inexpensive; it's a much better air filter than the paper air filter in the Honda XR650L.

Spud

[Spud Rider]

Originally Posted by strongbad

The OEM filter isn't paper. It's oil-impregnated paper. You'd be very hard pressed to find a more efficient filter.

Indeed, the OEM air filter for the CRF250L appears to be an excellent, inexpensive air filter. However, the fellows at Best Dual Sport Bikes claim their Uni Air Filter will yield a little more horsepower than the stock air filter.

http://bestdualsportbikes.com/dual-s...honda-crf250l/



Nevertheless, I wonder if the modified, Uni air filter will seal as well at the edges as the stock air filter. Also, I don't know if it's worth $100 to try to get that slight increase in horsepower. It's obvious the OEM air filter is doing a pretty good job, and I'm sure Honda designed it to seal well at the edges.

Originally Posted by Ed@Ford

Is there a cleaning process described in the service manual, or owners manual, or is it like a car....just replace on a schedule....

I would always keep a spare, OEM air filter handy. I would periodically knock the dust off the used air filter, and I would occasionally clean it from the inside with compressed air. When the used air filter accumulated a lot of dirt I couldn't remove, I would substitute a new air filter, and see if the bike performed better. When the engine made discernibly more power with a new air filter, I would throw the old filter away and install a new one.

Spud

[bungie4]

[QUOTE=Spud Rider;20221170]
I would always keep a spare, OEM air filter handy. I would periodically knock the dust off the used air filter, and I would occasionally clean it from the inside with compressed air. When the used air filter accumulated a lot of dirt I couldn't remove, I would substitute a new air filter, and see if the bike performed better. When the engine made discernibly more power with a new air filter, I would throw the old filter away and install a new one.
/QUOTE]

That makes far to much sense. You should be ashamed of yourself.

Theirs a considerable amount of real world evidence that some brands of aftermarket oiled gauze filters are a great way to prematurely wear your engine out. They just don't filter as well as their advertising leads you to believe. Now given that their power claims are already suspect....

[Spud Rider]

Originally Posted by bungie4

That makes far to much sense. You should be ashamed of yourself.

Theirs a considerable amount of real world evidence that some brands of aftermarket oiled gauze filters are a great way to prematurely wear your engine out. They just don't filter as well as their advertising leads you to believe. Now given that their power claims are already suspect....

I suppose a gauze (K&N) air filter works okay on the street. However, I would never employ a gauze air filter in any dual sport or off road motorcycle; the gauze air filters allow too much dirt to enter the engine. Once again, I strongly disagree with the statements in the following video regarding paper air filters. However, I do agree with the statements made regarding foam and gauze air filters.



Spud

[mxbundy]

Originally Posted by G19Tony

Could I request that for my seat when I order it Bundy?

Very nice looking. I'm going to try and make an overnight trip to the Slabs next month. It's a 325 mile run from Vegas.

The first LOW seat is out of the mold, will be ready to start shipping late next week.

Bundy

[strongbad]

Originally Posted by Spud Rider

...Nevertheless, I wonder if the modified, Uni air filter will seal as well at the edges as the stock air filter...

I can't speak to restriction of air flow in one filter type vs another. Dynamometer measurements would be needed to prove which is best and I'm dubious of dyno runs done by a product vendor. No conflict of interest there...

One of my hobbies is oil analysis, so I can speak to filter efficiency (ability to trap dirt). After looking at hundreds of oil analysis reports and experimenting with my own car and bike, I can say that oiled foam and paper both have excellent efficiency (if the foam is oiled correctly). Oiled gauze ranges from pretty good efficiency to awful depending on how much oil is used. Both my car and bike had paper filters OEM, and I had lots of good baseline oil analysis reports before switching to UNI oiled foam filters and BelRay foam filter oil. Silicon and wear metals were no better or worse than paper after switching to oiled foam.

The problem with oiled foam and gauze is that it's very important to use enough oil and distribute the oil evenly throughout the filter. Also, the oil has to be thick enough that gravity and air flow don't force the oil away from certain parts of the filter. I'm going back to the OEM paper filter in my car because I'm sick of cleaning and oiling the foam filter.

I don't have any experience with the "viscous" filter Honda is using in the CBR250R and CRF250L, but I suspect it's very efficient. In any case, I would not experiment with non-OEM air filters without having a good oil analysis baseline with stock so that I can verify that the new filter is working. Dirt is extremely abrasive stuff and it doesn't take much to do a lot of damage quickly.