crf300l rally horsepower mod airbox mod and air filter upgrade

CRF300l rally horsepower mod 1 of 3. The CRF300L Rally is a versatile lightweight dual sport adventure motorcycle at a very modest price point compared with most "Adventure Bikes". But, it has two main weak points. One is soft suspension and the other is the 300 is down on horsepower. This video is part one of three. A simple horsepower modification that most riders can do on their own without a lot of technical expertise. The combination of the three mods in this series will deliver a noticeable improvement around town, in the dirt and improve power and top speed on the highway.
The three CRF300L Rally horsepower mods that we will cover in this video series are 1. improving air intake, 2. improving exhaust flow, and 3. optimizing the fuel mixture for optimum performance and longevity.
While there are more complicated mechanical modifications that are available to riders who are mechanically inclined, or willing to pay for, these first three horsepower mods are definitely the most accessible to most riders. And they deliver a noticeable improvement for a relatively moderate expenditure of time and money.
You can find the DNA Air Filter here:
amzn.to/3qaZnK5
Filer Vents are available here:
amzn.to/3YdEvys
I hope this was helpful, I'm always delighted to get your questions comments and feedback.
More info on this and other topics at dualsportgarage.com
Consider supporting this channel by picking up merch at www.dualsportgarage.etsy.com
Thanks for watching!
00:00 Introduction
01:38 Getting Started
03:52 Stock Air Intake
05:00 Targeted Air Increase
05:43 Air Box Cover Mod
07:45 Air Box Mod
10:54 Air Filter Upgrade
13:11 Highlights and Take Aways
13:32 Conclusion
Looking to get your hands dirty...more complicated modifications are possible...if you're mechanically inclined.
Here is a link to one such video (Jake shares a ton of detail ):
• CRF300L CAMSHAFT SWAP ...
Note: I received no free product and I was not paid to make this video. This channel is subsidized in part by small commissions paid on some, not all, product links. And as an Amazon Associate, I earn from qualifying purchases. So it is helpful and very much appreciated when you use these links to support this channel.

[@stephtraveler7378]

Dont. Ditch the crash bars. A complete new set of plastics can be had for as little as $190. You added weight w/ little benefit. The air box mod AND muffler (merely slipping on a new muffler) had zero effect on power. It merely gets louder (making you think its faster) Leave the stock filter in there. Sand gets by the foam filters. You see and learn this when you rebuild motors.... Taco Moto did dyno testing on these mods you're recommending. They provide zero benefit. The Japan engineers got it right coming out of the factory. Leave it stock. If you do the ECU, you need to make hardware changes to see a benefit (exhaust header). You want serious performance gains, change the cam, piston, ecu, header, and run high-octane. Otherwise, leave it stock and enjoy it for what it is. Its a great bike in stock configuration.

[@HippieHoller]

U mean CBR 300 cams and piston? Or 550 cams, ecu and big bore?

[@pzchannel6444]

Not reinstalling that grommet is genius! No more removing the seat to get to air box. Thank you, sir!

[@dualsportgarage]

Happy to help!

[@seansteede]

I second this comment! I hate removing the seat on this bike, one of the two bolts always gets cross threaded while trying to get through the washers and spacers for my aftermarket rack...what a pain compared to so many other bikes I've had. This one little piece of info will be saving me a ton of time! Thanks.

[@MidCoastAdventures]

Great little machines the 300 Rally. Very happy with mine, and a joy when adventure riding. Cheers for the upload 👍

[@dualsportgarage]

Agreed…some folks on KZbin don’t love the bike but I road it to Dirt Daze this year… over 500 miles there and back and on the group rides…no issues…just good fun. Thanks for the comment!

[@trippdean1879]

Hey Chris, Wow you are very very good at producing KZbin content!.. and your info is so comprehensive and easy to follow. Please keep up the great work. I took delivery of my Rally, her name is "Andorra", as that will be my destination expat country sometime in the next two years... and I'm in the process of gradually upgrading her, so your videos are my top go-to info spots. Thanks again. Tripp in Ithaca, NY

[@dualsportgarage]

Thanks for the kudos …good luck with your new ride!

[@chrisvonkleist3984]

Some additional mods to the 300l transform it nicely. To start with you can add two vents to the airbox as per the video (but place the side cover vent to the left), or simply cut the holes and don't install the foam vents-the air filter will take care of dirt/dust entering the box. Next, remove the snorkel and cut off the 2.5 inches that protrude into the airbox then reinstall. Remove the backfire screen from the stock air filter and it will work fine. Removing the pair valve, canister and associated hoses shaves 1.3 lbs and allows air to circulate better behind the cylinder. I added the Yoshimura slip on mainly to lose weight and get rid of the excess heat generated by the catalytic converter. You can make it quieter by installing a 2" drain screen on the end of the slip on secured with 3 small self tapping screws. Bike runs great with these mods (even with the stock pipe) but even better with the yosh and a stage 1, 91 octane ECU flash from 550 performance. Gas milage been reduced minimally (about 1-2 mpg). At 170lbs i found the suspension too soft so I change the fork fluid to 15wt to slow rebound damping and added 10cc to resist bottoming. Fork works great now. The shock is useless so I swapped it for a Cogent Ohlins unit. With these mods the bike runs as it should.

[@samylsneh6186]

Absolutely love the front feeling guard and rear saddlebag guard/carrier what's the brand?

[@dualsportgarage]

Both are by Outback Motortek …I’ve used their stuff on other bikes …always works out well.

[@dualsportgarage]

Oh and the top rack is by AXP.

[@Ride2Live420]

Third main weakness. Weight. And it feels top heavy to boot. If it could lose 50 lbs I’d ride it harder. “Not you honey I was talking about my bike!” (Muttering - For you it’s more like 100) “I said you’re perfect the way you are”

[@dualsportgarage]

After riding my 300 two stroke I would agree, but after riding most "Adventure Bikes" this thing is very light. Though not an ultra light Adventure bike like the 500exc...I might have to build one of those next....but I have a feeling I would be sacrificing a good bit of comfort in the process. Thanks!

[@240LTS]

... Curious why didn't you drill the hole in the cover on the top LEFT side where it was open to the air box? Instead you chose the top right side where the vent had to be modified and the air flow is blocked by the side of the air filter defeating the purpose in the first place? . Take the 1" hole and subtract the thickness of all the plastic that covers the breathable opening and it looks to be about half, or, measure (somehow) the visible blue foam and see how much room there is for air to pass through. . Jake the Garden Snake removed the snorkel and cut a big hole in the top back side of the air box then put a short rubber tube in the hole and sealed around it. . I keep searching ways to increase my 300 Rally's power (different air filter and full exhaust, ECU flash) but for now I am going to leave everything stock. I want reliability, longevity and minor maintenance more than 3+/- more horsepower. . To each their own. Thank you for the video. .

[@dualsportgarage]

I hope some of the value of my videos bring is that you all have seen it before having to doing it...placement of the air box vent is a case in point. I don't think I would ever shoot "cleaned up" videos just for the camera without mistakes or imperfections. Would I place the outside vent further back...don't know...I know the top vent would be further in to avoid that screw. The next two videos will showcase the EJK piggy back EFI controller and the next I will replace the ECU with a 550 Performance ECU. We will see if these make the bike more fun. To each his own for sure...I'm gonna keep sharing so you all can decide either way. Thanks for asking!

[@240LTS]

@@dualsportgarage Thank you. I do enjoy all your videos. I know it takes considerable time to set up, record, edit and post. I appreciate all your work. Jeff

[@AceCarleton]

You did not double your vent area. The stock snorkel has a diameter of 1.5 inches so the area is 1134mm A 1 inch hone has an area of 490mm x 2 = only 980mm so not quite double and that does not include the losses along the walls of the vents

[@dualsportgarage]

you are correct... I figure it is approximately 188% of stock...given that the DNA air filter flows a little over 150% ...the air box should now flow more than enough air to feed the air filter. Thanks,

[@AceCarleton]

But it isn't 188% the pods fit inside a 1 inch hole and the lip of the pod in 2mm think so the inside of the pod is only like 3/4 of and inch. Then you have the thick plastic mesh blocking half of that 3/4 inch hole. So really only 3/8 or 7/16 more opening and then there is air drag on every edge. So when you flow test the vents on a bench it ends up being worthless. Also the factory snorkel behind the dna filter, between the airbox and throttle body is still only 35mm

[@SlipperyJack60]

This is assuming that the snorkel air inlet is a limiting factor on the air intake. Yes, you have opened up the external air intake area but did you need to? Are you also adapting the post filter air intake routes? If not, why not as you've only adapted one part of the air intake route? Anyway, back to my first sentence, I reckon the air filter (of any type) would be the limiting factor to any airflow, regardless of the type of filter. So, my advice would be fit the high flow filter and leave the air intake vents alone and go and have a few beers instead.

[@twc9000]

550 Performance makes an airbox lid that has a large oval cutout for $50. Your method is cheaper at $16 and keeps the air intake higher.

[@dualsportgarage]

Good to hear…thanks for the feedback!

[@AceCarleton]

the vented lite plugs dont work. dont waste your money

[@maxpe111]

@@AceCarleton why?

[@AceCarleton]

Most of the Hole is covered by plastic and you have drag on the plastic mesh. You can google fluid dynamics and velocity stacks and get great information on designing a proper intake tube for the box@@maxpe111

[@stevenrees6015]

You didn't put the seat on properly 😛

[@dualsportgarage]

The T post on the tank needed a little bend to make it easier to get the front of the seat to fit under it consistently...caution...be super careful not to crack the paint if you do this... to be expected on a mid-priced dual sport vs a race bike.

[@ivorscruton5121]

Honda has been on the cutting edge of 4 stroke technology for over 70 years, having been involved in Moto GP, Formula one and Indy car racing to mention a few. Had they wanted to make the CRF 300 a 50 hp powerhouse, they would have done so at the sacrifice of reliability, so they instead created a competition version which is double the price, significantly lighter whilst needed more maintenance. So I question people who without having flow tested components, have the ability to conclude they restrict engine output and manage to do so without having a baseline dyno reading, or post modification result. People who have done so have concluded there is no gains to be made in the aspiration, including the exhaust without introduction of additional fuel, which itself voids the emissions compliance, that Honda had to meet in order to market the motorcycle. The aftermarket will quote figures of 200% airflow increase over stock, or whatever, but that's meaningless if the engine only requires 50% of stock flow, for arguments sake. To increase power, a combination of modifications is necessary, such as displacement, compression ratio, increased valve size and fuel mapping. The end result would be higher power from an overweight street bike engine in a chassis not specifically designed for off road use. The amount spent to gain significant increases in power would likely be the same as buying something more competition oriented and certainly not have the reliability.

[@user-yo1pk4ky4k]

When will people quit hacking these airboxes? Fluid dynamics engineers at Honda figure out this black art of air intake design. By drilling the airbox, removing the snorkel, etc. you destroy the resonance and reduce performance. The stock airbox, snorkel, and filter are designed to let in much more air than the bike could ever use. It does not need more air! It needs the pressure wave of dense air to hit the intake valve at the right time -- which you just ruined by hacking the box.

[@markjacobs3956]

This has to be one of the stupidest mods ever. Just take the side cover off completely and leave it off. If you are not going through deep water, don't worry about it. If you are, leave it on and leave the snorkel in. If you grease your gasket on your air filter and it is tight, nothing is getting in. Selling crap to newbs to think they're gonna get .000001hp. Shame.