CRF300L Modifying the Stock Exhaust

[@ChiliBuRevolution]

Butt Dyno wins! lol nice little mod eh Scoot, a bit of a ride along too so thanks for that as well, have a beauty day eh and enjoy the gift that they all are my friends, ride safe & ride often, B^)

[@Scoottoots]

Yup, the butt dyno is happy :-)

[@13nikoleo]

A video showing the difference in stock vs modify sounds pls 😍

[@Scoottoots]

Yeah I should have done that. I said in the video as much. Can't be done now though.

[@mrcla55yguy20]

Lol. Record your stock exhaust, and splice the video. Problem solved😂. Only jk of course, but it’d work🤷🏻‍♂️🤫🙂

[@phantomshtter]

You can't capture true sound without expensive precision audio recording equipment. Much less such a small difference. Watching videos to hear exhausts is pointless, it NEVER comes through true to in person, not even close.

[@hatfunnytv]

I did something very similar to mine, I removed the wield on the front porción of the spark arrestor and took the front part out. The sound is very good 👍 not to loud, in my personal opinion it is better than a slip on exhaust 👍

[@Scoottoots]

That's a good method. My welder was stolen, so I made do.

[@asafnaot]

Did you take a picture of your mod?

[@stevepope5484]

I can't help it? Knock a hole in the end.Done.

[@Casey_Schmidt]

I did something similar to this to my CRF250L last year, I'm still really happy with the mod. I'm glad you found a similar solution!

[@Scoottoots]

Thanks. I also did a similar mod to my 250L, years back. I think I have a video on that one as well.

[@skaragianis]

Smart idea. Good courage just having a go, and looks good! Sound is important for enjoyment so happy your’re there. I regret wearing earplugs with my FMF. Halfway would’ve been perfect. I need to find motivation to extend that pipe!

[@Scoottoots]

Thanks Steffan. The aftermarket exhausts can be toned down in sound. I did that on my Yoshi system years ago. It involves screwing a stainless steel drain screen to the tailpipe. It increases back pressure and lowers the sound. I had to lean the mixture a bit to balance that out.

[@simondemetriou7750]

Great idea I’m going to do mine tomorrow! Also, try taking the snorkel out of your air box if you want better pull, and a lovely deep induction noise on the throttle!

[@Scoottoots]

Thanks Simon. If you do it, a better way is to just completely drill out the end plate without cutting the end of the tube off. Then if you have a welder you can weld a spark arrestor screen onto the end of the tube where you drilled the plate out, grind it clean so the tube fits into the hole it came out of, and it's nice and neat. Bit of a tricky weld though. I had to cut it the way I did as someone stole my welder. The method in the video works just fine though. I haven't removed the snorkel. I may try that. On my 250L I cut out a larger hole for the snorkel, then created a new larger diameter snorkel from a rubber elbow. I also had an after market exhaust and a fuel controller though so I wasn't concerned about creating too lean a condition.

[@5ebra1]

That was a great explanation. The bike sounds nice now. Good job well done.

[@Scoottoots]

Cheers. I'm happy with it :-)

[@spctweaks]

hey just a quick question, when cops stop you dont they suspect or give you fines for loud exhaust exceeding DB and emissions etc? and what about STK (technical control of the vehicle) do you pass it with all these mods and are they street legal? I see so many people making mods and power mods but i always wonder if they just risk getting fined and stuff or does everybody ride illegally? Thank you for explaining.

[@Scoottoots]

The mod I did to the exhaust does not increase the sound level to the point it would attract attention, so no worries on legality there. Some modifications are road legal, others are not, and regulations vary from place to place. It's best to know what the regulations are in your area that are actually enforced, then choose your mods according to that and your preferred risk level (of getting caught). 90% of aftermarket exhaust for instance are not road legal. Some regulations are there for good reason. In the case of exhausts, noise, pollution, and forest fires. Approved spark arrestors are mandatory for riding off road in locations like mine. In most places ECU flashes or aftermarket ECUs are largely; all depends on how deep you dig into its effects on fueling and emissions regulations. It get complicated, so much so that police are highly unlikely to look for anything but the obvious, like an extremely loud exhaust.

[@claretbuck1882]

Awesome mod bud and free win win 👍🏻

[@Scoottoots]

Thanks, works for me :-)

[@josephpotterf9459]

On the noise thing a helmet at least all of mine makes road and bike noise louder. As a younger guy back in the day in Ohio we rode without helmets . or any protection unless cold weather counts . But I live in a helmet law state now and have gotten used to them . On my crf250 l I reinstalled stock exhaust luckily the kid saved all the parts.but traded it for the new CT125 I would have liked to keep both but not in the cards at the moment. I have noticed their going for almost new prices because of the gas situation. the CT1q25 gets 120 + mpg Thanks Scoot catch ya next time.

[@Scoottoots]

I remember those no helmet days also, in the 60's. And yes, helmets sometimes exaggerate certain frequencies. In my case it's probably heightening the bad noise and blocking the good sounds, lol.

[@jimdoolan2277]

Did the same thing on my exhaust on my honda 300L my exhaust is different had to cut end off we have the LED lights down here in new Zealand mybe different exhaust on this model 😑 great way to open up the bike and not over load at all Cheers

[@Scoottoots]

I recall Honda did similar with the 250L. Some countries had a different setup with no spark arrestor. But yes, some opening up helps without going too far.

[@s.l.6736]

are you still satisfied with this mod ? I just put the first 200km on mine and I have the same comments as you. is the screen you placed on the end of the pipe necessary? should I also remove the snorkel from the air filter on top of that? thanks in advance

[@Scoottoots]

Yes I am still happy with the modification to the spark arrestor and also with removing the snorkel. So I still have the modified exhaust, snorkel removed, air box intake hole enlarged, and backfire screen removed from air filter (at your own risk of course). The screen at the end of the spark arrestor where I drilled out the end plate is necessary if you ride in forest fire prone areas as I do, and/or where forestry regs require it. The combination of improved intake and exhaust coupled with the 550 stock improved ECU gives the bike a bit better grunt and of course better sound. I also installed a G2 Quick turn competition throttle.

[@s.l.6736]

@@Scoottoots thanks for your quick reply, I'll look for the right mesh and looking forward to the mods

[@ronald8673]

Jakethegardensnake, emission delete vid shows the rattle noise is from the secondary air injection system.

[@Scoottoots]

I saw that, but I think it's guesswork at this point. The 5,000 rpm rattle you hear about is more likely caused by the cam chain lifter assembly (Honda's term for the CCT). The noise I get is likely the backside of the cam chain slapping and some valve chatter, so not caused by the CCT, as it occurs under load. It's possible the reed valves for the PAIR system are causing some of it, but it doesn't sound that way to my ear. And since I'm not getting an aftermarket exhaust, I should keep the PAIR system intact, as I still have a CAT converter that is benefited by the extra heat the PAIR system creates in the exhaust. It'll be interesting to follow Jakes power mods, especially the aftermarket camshafts.

[@d1zguy864]

My Philippines bike does not have this noise not any emissions system and can run without spark arrestor here

[@tonylawton6513]

The noise is the clutch springs rattling its normal, easy fix with a heavier duty one instead of the slipper one that's fitted.....

[@Scoottoots]

Thanks, I hear that's true for some. I've listened carefully and I doubt mine is coming from the clutch. For me it's a combination of valve train chatter and the PAIR system rattling (reed valves). I did video the other day on that.

[@XnnorDaveB]

interesting … great vid 💪👍

[@Scoottoots]

Cheers Dave :-)

[@rileymoralee2923]

Whats the chamber thats right behind the spark arrestor? I wonder how well it would work on a stock 300 to cut out the mid section, and just leave the spark arrestor attached to the down flange...

[@Scoottoots]

As far as I can tell by shining a light through the opening to that chamber just behind the spark arrestor, and by inserting a long probe, it connects directly to the entrance to the muffler where the catalytic converter sits.

[@ryanpan109]

Does this mod do anything in terms of the excessive heat from the stuffy stock exhaust ??

[@Scoottoots]

Can't say this mod on its own does anything for the heat issue. Several mods combined have lessened it. Combination of opened out intake, opened out muffler, and 550 Performance stock improved ECU. Still gets hot but not nearly as bad.

[@davidroberts7490]

Good job 👍

[@Scoottoots]

Thanks :-)

[@interstellerdweller]

What would be the downside of removing the arrestor completely?

[@Scoottoots]

Two problems with that. 1.) the sound would be awful. I've heard it. 2.) Illegal to run off road without it in fire-prone areas like ours. The arrestor screen is not a restriction, but the diameter of the arrestor tube and tailpipe is, so a person could buy an aftermarket spark arrestor and couple it with a larger diameter tailpipe for more flow. Some fabrication involved.

[@ChrisBird1]

Wouldn't more induction noise help alot ?

[@Scoottoots]

Yup, that helps also. I opened out the airbox and I now have a K & N air filter. It's the way I like it now 🙂

[@ChrisBird1]

@@Scoottoots thanks for the info

[@robvanderlinden6663]

Hello i have the 250 l from 2017 what you mean is that you the pipe on the end you must make open And can it whitout that stoff whit little holes Pls let me no thks

[@Scoottoots]

I don't know what the spark arrestor on your bike looks like, but on this one I drilled out the end cap on the arrestor and covered it with a spark arrestor screen to increase the flow rate. Hope that helps. The screen over the end is to ensure it remains a functioning spark arrestor for trail riding.

[@robvanderlinden6663]

Ok i have the same one but can i let stay the it originel and only cath of the end works that also Let me nu thks please And give this no dammits on the motor Sorry for my bad english🙈😂

[@Scoottoots]

@@robvanderlinden6663 If you mean, you cut the end but did not install the screen over that end, then it will be fine. No harm to the engine. Without the screen you will not prevent sparks from exiting the muffler which is a forest fire concern. This engine though is not likely to throw sparks out the muffler. I hope I answered your question.

[@aveguy451]

Glad you have a work around. I’ll have to file that away in case I need it. I think I have been spared that chatter with my Rally. Then again my ears may not be tuned well enough to pick it out. I think the fact I don’t hear anything that seams out of place means I probably don’t have that chatter. I wonder if the original length used that inner hole as a support? Now it is held only on one end. With vibration it may stress the mounting where the screws are? Probably not an expensive part to replace if that were to happen.

[@Scoottoots]

Yeah I think mine is just different in that way. The better way to do what I did was to leave the tube intact, drill out the hole and tack weld the screen into the tube over the hole so the tube could still be inserted. I should have said that on the video. I couldn't do it like that as my welder was stolen. I doubt any support issue will ensue as it is held by three bolts. I did a similar mod to my 250L stock exhaust and it lasted fine.

[@SeanSR]

The 5k rattle is real and annoying!

[@Scoottoots]

I hear ya :-)

[@jamesluisitobinoya4856]

There's a chattering sound and the mechanic will just said that it's normal, I though the mechanic would tell that place an earplug in your ears so that you cannot hear it anymore, it's only a joke statement my friend actually I also owned a crf 250l.

[@crflexadventure8103]

Question instead of cutting the exhaust why not just drill out the plate blocking the airflow

[@Scoottoots]

Yup, drilling out the end of the arrestor without cutting it shorter would be easiest, but attaching a spark arresting screen into the tube to cover the drilled opening would be tricky for me, as my welded was stolen. Couldn't wrap the screen over the end as then it wouldn't fit through the tight opening. I should have mentioned that.

[@crflexadventure8103]

@@Scoottoots Is your purpose of the screen to keep from flame outs

[@Scoottoots]

@@crflexadventure8103 Yes, it is illegal here and in most of north America to run without a spark arrestor. Here especially it is a must if riding off road. Very dry summers and lots of wildfire activity. This bike is unlikely to emit sparks but if a conservation officer checks... ;-)

[@KC-fu6qd]

Try earplugs , makes a big difference.

[@Scoottoots]

I have custom earplugs in a pouch in my jacket. They don't seem to help, lol.

[@motochavannigans708]

It's the PAIR valve system making that noise. The valve cover has a port that works with the PAIR system. The flange that sits valve cover has a small reed valve inside. Even with engine blockoff plates that part goes back on because it's integrated to the gasket. Some people have pried the Reed flapper out of the gasket and said the noise went away completely after that.

[@Scoottoots]

The PAIR system can certainly make noise, however since my engine noise was always present at all rpms it is unlikely to be the primary cause, as the PAIR system does not operate at all times. When the PAIR valve is closed and not drawing air from the air box, air is not moving through the reeds. I removed the complete PAIR system on my 250L. The only good reason to do that though is when you have an aftermarket exhaust without a CAT, to stop the subsequent popping on deceleration. Removing or disabling it with a stock exhaust will 'very slowly' clog the CAT. I'm sure it contributes to the noise for a lot of owners as most complain of the noise only within a certain rpm range. Mine was at all rpm. Now however (several weeks after this video) it has toned down to a non-issue. Strange but satisfying outcome. Something must have changed internally :-)

[@urastus9202]

It doesn't seem right that you have engine chatter. I've owned a lot of motorcycles and only one had a noisy motor; yamaha ttr600 made in Italy. I hated it because it wasn't right. Thanks for the cheap mod - this is looking like an expensive bike by the time you fix the suspension alone.

[@Scoottoots]

I agree, it doesn't seem right. Built to a budget I guess. That said, I feel it's worth the investment to upgrade the suspension. So much better to ride now, and I'll likely keep the bike forever.

[@urastus9202]

@@Scoottoots For sure. Most bikes seem like this, esp. rear suspension. They all seem to be aimed at 70kg sedate riders

[@mrcla55yguy20]

The stock exhaust makes the engine sound really tinny on all the bikes with this motor. Sounds like there’s an empty soda can in there somewhere. I hated it. It’s worse with the 300l.

[@mrcla55yguy20]

Will this damage the engine?

[@Scoottoots]

No it will not, but if you do other modifications that also decrease back pressure and increase intake flow, then it's wise to adjust the fuel mixture. Enrich it a bit to compensate for the lean effect from the increased air. I have a modified ECU from 550 Performance (Stock Improved 87 octane).

[@mrcla55yguy20]

@@Scoottoots Awesome thanks. How many miles have you put on it since you’ve done that?

[@Scoottoots]

@@mrcla55yguy20 I'd be guessing but likely 3,000 miles give or take.

[@mrcla55yguy20]

@@Scoottoots thanks for the replies. Nice to see an older than myself kicking it still on a bike. I plan to do the same. Just picked up my crf300l( dream bike)….I’m easy to please. I want the exhaust, like you, to be audible just for shifting purposes but not too loud. You got a good balance it seems. Anywho, I subbed, I’ll watch your stuff🤙

[@Scoottoots]

@@mrcla55yguy20 Thanks, and congrats on getting the bike. Enjoy it! 🙂

[@asafnaot]

Can you specify the measurements where to cut the tube? Did you observe any engine behavior issues following this mod?

[@Scoottoots]

I can't now, after the fact tell how much to cut. If you can weld a spark arrestor screen in the tube end after drilling it out completely, you wouldn't have to cut at all. The only reason I cut the tube is because my welder was stolen so I had to wrap screen around the end and secure it with bailing wire. Because of that the tube can't fit through the hole in the middle plate. I cut just enough to allow the arrestor to be installed. No engine issues ensued. There was a bit of popping on decel though, but very little. Since then I have installed the 550 performance stock improved 87 octane ECU and I have opened the air box a bit further also. No popping on decel now (not that that is a problem). The bike runs fantastic :-)

[@asafnaot]

@@Scoottoots It turns out that on my bike and I guess on all EU bikes this mod is not applicable. The end pipe is welded in there. No bolts.

[@Scoottoots]

@@asafnaot Yeah they are differently constructed. I should have mentioned that.

[@robvanderlinden6663]

Hello not good mij honda crf 250 l I take of the end pipe and its not whit 4 bouten anymore its was make whit lass so i cant make that😢 I think the was do this because everybody cut the pipe of My homda is from 2017

[@Scoottoots]

Sorry, I'm not sure what you mean to say. The language is not clear. I know some country's models have a different muffler that does not have a removable spark arrestor due to different forest fire regulations.

[@robvanderlinden6663]

@@Scoottoots yes i have this☹️do you no a good pipe and cheap thks

[@Scoottoots]

@@robvanderlinden6663 I think the cheapest pipe that is popular is the Motoz pipe sold by BikerzBits in Thailand. Not sure if they have one for the 250L though. Check them out.

[@robvanderlinden6663]

@@Scoottoots thank you very much 👍👊👊💪

[@theoriginalEmuman]

have your iced a poly bash plate. Cuts down the engine noise heaps…..

[@Scoottoots]

Not sure about what your first sentence means, but I have a plastic bash plate on the bike. No added sound from that.

[@stevepope5484]

I'd just remove the spark arrestor period. Unless I was trail riding. I'm I don't like it/reinstal it.

[@Scoottoots]

We live in a high risk wildfire area and so the spark arrestor is mandated off road. If you were to just remove the spark arrestor, the sound is not good at all btw ;-)

[@stevepope5484]

Thanks. I've tried a couple times to pop the front tire off the ground? Must be heavier than a New XR 250 was.? This tank needs to be nearly red lined to budge! I'm guessing. Even my new XR 200 in 84 was a fun wheelie machine. At 66/guess I'm too old anyway.

[@Scoottoots]

@@stevepope5484 I'm no wheelie artist for sure, but the front end will come up pretty easily if you have the knack. I do not though I've done it. A buddy rode mine and he lifted the front end with no revving; just the right touch on the clutch and throttle. Seemed effortless.

[@2wheels327]

I would wait till your warranty is over. You may nil your warranty doing that.

[@Scoottoots]

No it won't void warranty. Lots of dealers sell brand new bikes with aftermarket exhausts on them with full warranty intact, and they alter the fuel mixture far more than a conservative approach like this. My warranty is up in June anyway :-)

[@2wheels327]

@@Scoottoots That's an aftermarket exhaust, not a cut up stock exhaust. Totally different

[@Scoottoots]

@@2wheels327 To my knowledge It won't void warranty. What about digitally altering the ECU? This is drastically less change than altering the ignition timing, RPM limiter, and A/F ratios with the 550 flash of the stock ECU that tons of owners are doing.

[@mikeschlup5279]

Reflash the ecu...550 performance!

[@Scoottoots]

That'd be cool and all but with gas pricing going through the roof, no way am I going to pay for 91 octane. I'll keep the economy stock :-)

[@marcochavane3124]

@@Scoottoots they offer pump gas tunes as well. Not all of them require the good stuff.

[@Scoottoots]

@@marcochavane3124 Yup, I saw that the other day, though the timing advance is important for more power. Cool though that they offer the options they do now.

[@someguy5035]

Or you can take the SA out...and just not put it back in and skip the middle steps.

[@davidroberts7490]

Sorry you got me there. Whats the SA

[@tokerty]

Spark arrestor

[@Scoottoots]

No, that is not an option at all. I live in a province with heavy wild fire in the warm months. As in most areas in North America with a lot of forest, it is illegal riding off road without a spark arrestor. Conservation officers can check with a wire. Also, without the spark arrestor, the sound is a lot louder.

[@someguy5035]

@@Scoottoots Mine are still in, but I consider taking them out every once in awhile. There is no evidence that exhaust particles have ever caused a forest fire. I respect people that want to leave theirs in for that reason though.

[@Scoottoots]

@@someguy5035 Yeah I hear ya. These bikes are very unlikely to shoot sparks out the tailpipe. Regulations though. Big fines, etc. The biggest fire hazard comes from the header pipe. Stop or drop the bike in tall extremely dry grass after hard riding and it can easily start a fire.

[@exploder69]

If the 300L uses an O2 sensor, then it should adjust the mixture on its own, at least for highway conditions where extended lean burn would really add up. Unlike my XT250, that doesn't use an O2 sensor, and therefore absolutely needs an injection tuning device with any intake or exhaust flow mods. Of course my mind goes back to wondering why the engine chatter in the first place? Am I correct in understanding this is a common issue on the 300L? And if so, it seems like a problem begging for somebody to find a solution, because many people do want their power as quietly as they can possibly get it.

[@Scoottoots]

The noise has to do with being a single cylinder engine setting up vibration internally, especially on the cam chain. I don't know if most are like mine. Perhaps I'm being picky. Most people seem to complain of a CCT caused rattle at 5000 rpm or so, but that's not my issue. This engine has history in the CBR300R for many years. Yes, the O2 sensor will adjust enough for this conservative modification.