Is the airbox mod crf250 rally & 250L worth it?

[@nickfry7705]

Never mind airboxes, that fence needs sorting out first.

[@H3avyHaul3r]

over the the years of modding bikes and doing the “airbox mod” i’ve come to figure that while there may be no discernible HP gain…the ease of pulling that air through is essential for assisting the motor to produce that HP/torque easier than a closed airbox…

[@lightweightadv]

So true 👍🏻. It definitely makes life easier for the motor and should change the bike characteristics for the better on any machine 👊🏻😎

[@gordonblackley8863]

Interesting fact on the airbox mod after my 2000 mile TET trip………… more mpg!!!!! Didn’t see that coming. I saw a small drop in mpg after doing it, but I think that was down to playing more and using the extra power. I actually think it’s just about the same, but this trip I happened to ride economically. Who knew huh?

[@DavidKD2050]

Yeah my eyebrows raised when he said “more”. Sure, if you have it pegged most of the time I’d agree. But mild to moderate usage shouldn’t see an increase, if anything a reduction in consumption.

[@orical2832]

I removed the snorkel on my 2019 CRF250L but soon put it back in. Couldn't stand the noise.

[@PatchedBandit]

Running more lean can give more power but without adjustin the fueling running too lean can be quite bad for the engine.

[@garthwaters5756]

thanks mate, awesome as usual :-)

[@tiggerable]

Thanks for the info! I'm not going to do that mod for a lot of reasons I got the bike for in the first place and also mentioned here; 1. Lower milage (Climate change, long runs), 2. potentionally more noise on and offroad (Distubing nature), 3. Just 3% (not that much improvement). I might replace the standard filter to something more breathable though, but as said, everyone needs to make this decision for her/himself! Shiny side up!

[@nickfry7705]

Me again, Just realised you may have done both the holes in the airbox and the K&N together prior to the test. I've done the K&N but not the holes and would be really interested in how much of the gain comes from the K&N and how much from the holes. If the holes don't contribute so much then prob makes sense to just do K&N and have safety of reducing risk of water ingress if you drop it in a stream.

[@gordonblackley8863]

Sorry, just seen this. This was my mod that I gave to the guys, and I saw the 17% with the stock air filter, with the flash guard removed. Main reason for fitting the K&N was to get the flash guard back, but in testing on its own the K&N didn’t give these dramatic results

[@minkyhead]

i did this mod and took the bike to a dyno to set up a ejk ..the result was zero ..zero difference with airbox open or closed cant say anymore than that tbo but thats what happened ejk was next to usless too as in places the bike needed the a/f ratio lowering and the ejk can only add it ..the end result was the bike ran better stock than with the airbox mod or with a ejk ..ended up puttinga cbr300 motor in later and that runs just fine with the standard box unmodified

[@minkyhead]

@@lightweightadv 300 is good 4 years now ....managed to put a full 450x front on as well cheasp to buy ..ill deffo buy a new 300 when they come 2nd hand ..miles are clocking up now on the old one but no hurry yet glad honda has save us a shitload of hassle by bringing it out

[@nickfry7705]

Quite surprised at that, I always thought it would be a waste of time. I do however have reservations about loosing the snorkel following an incident in a puddle where I lay my bike on its side in 2' of water the other week. Bugger, there always has to be a downside doesn't there. Performance vs risk as ever.

[@joecamel6835]

Bam !

[@lightweightadv]

Yup

[@עידוכרם]

The guy that I bought my bike from took out the snorkel and all of the oil vapor got stuck in the air box instead of getting out. It made me putting the snorkel back and not wanting to even consider the air box mod for a while. Wonder what's it like in your air boxes and if you could do a video on the long terms effects of the mod. Sincerely, Ido, a crf250l owner😁

[@עידוכרם]

@@lightweightadv Cheers mate! I'll gladly watch that video!

[@kamil9194]

Well... I'm watching various videos about modifications for CRF250L. It seems that this airbox mod beat them all :) next would be a exhaust pipe. and Rear Gearing. i think no need for EJK to have those performences from this bike :)

[@joeray5394]

Do you have the EGK fuel controller installed on eithe test bike?

[@lightweightadv]

Hi Joe, no, we've never gone doe the EJK route. The rally however, does have the custom maps and programmable ECU that we have helped develop. It brings torque up to CRF300 levels and adds 5-10% bhp in the low range 👊🏻😎

[@stormshadow4799]

How did the top speed change?? Before, after??

[@lightweightadv]

Hey, good question. To be honest, we haven't specifically tested it as the top speed isn't our focus. The bike can still reach 80 mph (indicated), as before 👍🏻

[@joebernadetteg.3761]

You mention a decrease in MPG. How much of a decrease?

[@lightweightadv]

Hey, the decrease is minimal, but in such a small tank, you can notice it. I think the decrease is largely down to the fact that it increases the torque a lityle, so you enjoy the throttle a little bit more 😂

[@hickokaviation2249]

Nice test! Those are great improvements. Are you and your mate the same weight?

[@lightweightadv]

Hey, yeah there’s not really much in it tbh, maybe a few kgs 🤷🏻‍♂️

[@1964mjc]

Interesting - thought this mod had been dismissed years ago on both dyno and other forms as doing not much at all !! So this was air filter and drilling the box combined..(ie you changed two things at same time). Your results seem to counter previous ... you sure this isn’t down to just the filter change (ie just change one thing)

[@1964mjc]

@@lightweightadv thanks been riding a 250l for 3 years and never bothered because minkyhead and other respected Crf officiandios said it Dyno no difference.. have a 250rally with the cbr300r engine in too - might try it in that.. being in oz I run washable unifilter (very dusty in Qld) rather than stock or k and n ... but never really noticed any change over stock - maybe I’ll run a test on the 300 swap see if it does improve, cause my 250l is the older 2016 engine with less HP that post 2017..

[@gordonblackley8863]

@@lightweightadv I originally modded just the airbox and removed the flash / noise plate off the stock filter, in this state I saw 15% improvement, with the K&N too, 17% in the midrange. Basically throw more air at it and it loves it.

[@gordonblackley8863]

Nice to see my mods proven on other bikes. Of note, the economy loss you mentioned, is there when using the extra power, but on a run it’s the same as pre-mod at 60mph as the throttle isn’t as open for the same speed. What really peaked my interest was the lack of performance improvement from the exhaust, bearing in mind the L is lighter than the Rally, so will accelerate faster. I had never tested exhausts.

[@twowheels833]

@@gordonblackley8863 piqued

[@AA-wd2or]

I put dna filter i plan to buy cover with frog skin or put another snorkel

[@BrianDoherty-e8s]

Don't mod airboxes. That destroys the intake resonance that was determine by fluid dynamics engineering at Honda. It can lead to overheating and other problems that shortens life of the engine. Japanese automotive engineers know a lot more about it than backyard mod Jethros! The stock airbox is capable of providing several more times the air than the engine can use. Honda did not make a mistake that needs to be fixed! K&N filters let the engine breath better by not filtering as well as the stock filter. Leave engineered products alone.

[@DersNoNem]

Japanese engine are often underpowered especially Hondas. That's for longevity of a stock engines but Honda engines are bulletproof though.

[@riderdady4160]

🙂❤👍