Honda CRF250X & CRF450X Airbox Mod
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- Опубліковано 15 вер 2024
- www.rockymounta... If you own a Honda CRF 250X or a Honda CRF450X you know that your stock airbox restricts airflow greatly. One way to get around that limited airflow is you can complete an airbox modification and open up the airflow to your engine for significant power gains. Jay Clark walks you through the proper way to do this modification and open up the airflow to your motorcycle. We also provide you with some jetting recommendations to help with re-jetting your bike after you complete the airbox cutout. This simple mod for your Honda CRF250X or 450X is one of the most inexpensive ways to increase the power of your motorcycle. For a complete list of OEM and aftermarket parts and acessories visit our website www.rockymount... !!
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/ @rmatvmc
For my 250x I done the air box mod, pink wire, put a 250r pipe on, and used RM's jetting recommendation. Bike ran great, make sure alelerated pump functions like it should. (Ride in southern CA / western AZ)
First off, awesome and informative video. I did the smog kit removal, opened up the airbox (only the top, not the side door) and rejetted the carb using the specs you provided. The horsepower increase was noticeable and the acceleration is a lot smoother without any bogging or hesitation the way my bike ran previously.Thanks SO much RMATV.
I just used a razor with a new blade. When I was done cutting, I used a lighter to melt back those bits of plastic on the cut line to make it look nice.
whatever how you modify the air filter, carp, or whatever for more power there is a maximum speed which is set by the factory, and it will not exceed the maximum speed, unless you use power commander to reset the maximum speed
You sir are wrong. You can increase horsepower in many ways wich will give you more speed.
what altitude are the jetting recommendations for?
THANK YOU SO MUCH FOR ADDING JETTING SPECS!! love the hot knife deal
Anytime. Thanks for watching!
I see your running a Uni. Uni don't come with aftermarket cage.Would you say that is good filter?
i use k and n air filter install directly to the carp, no air box,and wow power increase a lot, however you need setting to more richer as this done by my mech, he right it work
Running no airbox with a clamp on filter is greatly going to increase airflow, but it will also tend to dirty a lot faster and you now run the risk of damaging the filter with dirt and debris that gets kicked up. It's open and exposed to the elements
Rocky Mountain ATV MC
i live in singapore and it is known to be a clean country
Rocky Mountain ATV MC
the filter is inside the engine and cannot see the filter from the outside
***** depend on the place you travel, if travel in dirty place than use full air box prevent dirt from entering the engine.
+Ryden Swalwell No. We are located in the United States. Payson, UT.
thank you very much for this guide very informative and high quality explanations
Awesome video
High speed oscillating multi tool would do the trick in about 1 minute or less.
Jetting recommendation for 250x seem way to rich. 170 main? Wow
hey. I did this mod on my crf 450x and replaced all the jets as shown at the end of the video. it ran amazing the first ride after doing this mod. then the second ride I would give it throttle off of idle and it would bog. I'm not sure if this has to do with the leak jet or not. could anyone plz help me on this one?
+Cody Acosta The altitude you're at could be the cause? The recommended jetting specs in this video will get you started, but not necessarily is it going to be spot on. You will need to fine tune your jetting. I don't think it would be a leak jet issue but more to do with your pilot jet and or air fuel mixture. Try those out and let us know if you have any questions.
Alright I'll try those two to see if it gets any better. Thank you very much for the feedback.
Ok so since the bike bogs down when given throttle and it is also unable to idle properly would I need a pilot jet a size up or a size down?
+Cody Acosta I would have you check where your air/fuel mixture screw is set at and see how many turns "IN" it goes, and remember that number. Typically 1-3 turns "out" is going to be the sweet spot. You can do "half" increments as well to better fine tune the air/fuel mixture screw instead of complete rotations if you want. Once you have your air/fuel mixture screw set, start the bike. See how it runs then. Could just need an simple adjustment? I'd also recommend you to check out some forums on for this 450x mod, see what others have done to better tune the carburetor.
It is because you RAPED your airbox by following this Fucked video!!! Just two or three 1" holes in the top of the box is MORE than enough airflow... AND you still get good Vacuum pulses which enhances the idle to mid-range transition....
Rocky Mountain MC - I'll ask the same question as has been asked on here before: What altitude are your jetting recommendations for? Is that for here in Utah, or is that for sea level? I'm getting ready to do this with my '06 250X so I can get it ready for the USRA desert series- just trying to get some quick jetting tips before I proceed. If you can answer that for me, that would be greatly appreciated. Thanks!
+Spencer758 These jetting specs are for California.
+Rocky Mountain ATV MC Dang, that's what I was worried about. I'll work from there. Thank you for the reply!
Spencer758 Anytime.. Good luck!
oh ya and that's with the stock pipe on the bike
What jetting should I start with? I'm in south Africa at 700m above sea level.
Hey man, I suppose the jetting you are giving at the end is the ketting for stock carb (membrane), do you know what jetting I have to run with a kehin FCR 41 carb and this airbox modification? Thanks by advance
I see that you have an aftermarket air filter installed once finished. What cage did you install to remove the screened OEM cage?
It looks like this bike has the stock cage but with the backfire screen removed.
Is this still a good mod to do on my X when its a timber sled in the winter or does that open the airbox too much to snow and water?
are you sure that's the right jetting for the 250x and 450x they seem like they are mixed up
+MRCV8350 These are some good starting points when doing this mod to your bike. May need to adjust depending on your elevation you ride in.
@@rmatvmc the 250x gets bigger jets than the 450x though? sure the figures weren't swapped?
I don't know about the 450 but everywhere else I've seen this mod it says the same for 250 jetting
guys, yourhaving the hesitation and bogging on quick throttle cuz your opening up the air way too much why would anyone think you need that much extreme air . I bought my 250 with the same mods .. bike had a big hesitation and don't even seem to have the power of a 250 . I closed up that huge hole some left a little bit of air in and whammo back to a 250 power and great throttle response even in the low to midrange revs , try it it works .
my 450x was all done b4 I got it.. with a 180mj. . do u think I should block some of the airbox off?only tops been cut ..
trail rider well it was only my top cut but the whole top part
so if its the whole top part opened up andtyour getting a hesitation esp. low end than yes .. trying closing it up and see if its better u can alwaysput it back to beingopen ifit doesn't work
andrew corrado thankyou
andrew corrado. How can you have too much air? The engine will only take as much air as it needs. You just need to re-jet to get the correct air/gas ratio.
I have a 2019 crf450l, and the airbox lid just comes off. Should I remove it before getting it Dyno tuned? I'm also adding an a FMF Q4 exhaust and mega bomb head from the X model. I'm using a power commander.
It really just depends on your preference. If you're going to ride the bike with the air cover lid off, tune it that way. You may just have to change the filter a little more often but I'm sure it'd pick up a bit of power! You could maybe even just drill some holes in the lid to get the best of both worlds. Let us know what you end up doing and thanks for watching!
@@rmatvmc if I take the airbox lid off, do you think I would lose any more or torque on the low end?
You shouldn't if you tune it with that set-up. It'd be really interesting to test both ways out and see if you can tell any difference in low end.
ua-cam.com/video/5rELGm3CAPUI/v-deo.html am having the same issue as in the above video. can you help? I bought the bike used and when taking apart the bike to do the carb I notice both the 2 hoses showing in the video weren't on anything. I cant seem to find where they go or how they are routed. please advice
+sean maskell I would have you check the OEM Parts Diagram for your machines Year, Make and Model. The diagram assemblies (Air Cleaner, Air Suction Valve and Crankcase) should help you diagnose where they need to be routed. I know on these Honda "X" models they have a bunch of breather hoses going into the air box and out. As well as some connected to the crankcase.
+sean maskell Here's our OEM Parts Schematic:
www.rockymountainatvmc.com/oem-parts/Honda
having same issue, did you figure it out
The 3 hp gain any normal guy can’t even feel isn’t worth the risk of sucking water and ending your day, or even ruining your engine.