Boost Bottles - Do they work? 

I did a boost bottle install on my pocket bike! I mention this video in my install... I lost one mph from top speed. I linked your vid in my description.

Just found this channel.. you deserve a whole heck of a lot higher ranking on youtube! Someone who has both the theoretic education AND practical experience to actually explain legit shit is a refreshing new thing that ought to become the next big thing :P

Common sense and science are powerless in front of wishful thinking : )

EXCELLENT VIDEO MAN!!! It's crazy how many people don't believe it when I try to explain how they're just wasting money on their cars by buying expensive "cold air intakes" and exhaust systems (and putting them on an otherwise stock engine). I can personally vouch for what this guy is talking about (especially what he begins to talk about at around the 14:00 minute mark)... I went to Universal Technical Institute in 1999, and they had added 3 extra "phases" of 9 weeks called "Hot Rod U"... We began with tearing down, blueprinting and re-assembling small block Chevy crate engines We then put them into T-Bucket "kit cars" and ran them on a chassis dyno. There was a stock-room full of various performance parts (camshafts, heads, intake manifolds, etc) which were donated by several manufacturers, and we installed them in our engines, after our baseline runs, to see the HP/torque changes. Anyway, to get to the point... During the last 3 weeks of the "Hot Rod" phases, we were able to try out various parts on regular street cars that were given to the school (LT1 Camaros, a T/A, fox Mustangs, etc), and the first thing that our instructor had my group do was to make 2 or 3 baseline runs of a stock 95 Z28... We then were given a $300 - $350 K&N "cold air intake" kit to install (which we had done in 30 mins or so, with the car still strapped to the dyno... (so there were no real changes in ambient air temp, humidity, etc). ON TO THE PUNCH-LINE : We made 2 or 3 more pulls with the new intake, and the car made 13 RWHP (That's not a typo!!! I said 13!!!) LESS than it did with the bone-stock air box and paper filter!!! ROFL...over $300 to LOSE 13hp at the wheels! True Story, folks! I'll NEVER forget it!

I'm from India, I have a 1997 Yamaha RXG, can confirm about the boost bottle/resonating chamber. It's said to help in the in-gear acceleration like if you are in 4th gear at 35-40km/hr and you whack open the throttle & the engine bogs down without the boost bottle.

saw your video for the first time and I already like it. You're like engineering explained but about bikes and more swearing

Love the reductionist dirt bike science. As a physicist and a dirt biker, this is the kind of component explanation I look for. Great stuff.

Love your honesty please have a spliff on the go as well

I made my own boost bottle on a 2 stroke scooter. With boostle hooked up I gain 3mph, without it I lose 3mph. So they do work if you have the right design and all that stuff he was talking about. The right volume the right neck length and diameter the length and diameter of the hose connecting it, the size of your engine. It is very possible to make positive gains with a boost bottle. My gains were without boost bottle 40mph and with boost bottle 43mph. Thanks great video

Hi you are totally right on boost bottles on single cylinder engines. I have dun a lot of dynotesting on Two cylinder snowmobile engines firing 180 degr apart there the boost bottle have more then a resonance flow. It will rally flow fuel/air mix between the intakes when cylinder1 closes cylinder 2 is opening and the mix will go from the closed reed side directly over to the other reed. On a 800cc engine each cyl 400cc the ID of the hose from the intake to the bottle or chamber must be around 25-35mm to make any power gain. And what i have seen in my dynos volume is not that important but best is about 300-400cc. And the entry in front of the reed needs to be like a funnel so air easy can change direction and go in to the short hose max 50-80mm up to the bottle or chamber. We can see power gains at max rpm in the 3-5hp but in mid range a bit more. I do a lot of testing with Helmholtz chambers in the exhaust on snowmobile engines mostly to get db down in some rpm ranges. I also manufacture turbo kits for two-stroke engines. I have a patented waste gate system to make it work. Right now i start testing twin screw superchargers on two-stroke engines. The problem here is to make a steady exhaust back pressure that follow intake boost so the boost stay in the cylinder and not go out in exhaust port. I have a working system ready. www.tikka.se www.snowmobile.se www.preburncatalytic.com I like your videos allot you are really good to explain things!! Thanks i do all dynotesting of new snowmobiles in the biggest snowmobile magazine in Europe snowmobile.se I have 5 dynos fully instrumented and build racing engines for snowmobiles. Both 2 and 4 stroke i also have dun some porting on wankel engines. Thanks again for a wery good channel Matts Tikka tikkarace@hotmail.com

I seem to have lost most of the afternoon watching your vids, Such a wealth of information, excellent no BS delivery, thanks...

There is a older gentleman called Ron McCord in Montana, he is the pioneer of this stuff and he makes a "Pulse induction" for CR500's and a few other 2T dirt bikes. The kit comes with a very modified PWK38 carby, modified Boyesen reed block and custom intake. Instead of using a bottle, it's a loop from intake to carby and thus it works at all rpm. Apart from a decompression button for easy starting, IMHO, the pulse is the best modification you can make to a CR500. My engine was jetted nicely but didn't like WOT at low rpm, it now pulls cleanly from 2000rpm, it used to sign off at around 7500rpm, I have now seen over rev to 9500+ on rev counter. Also much less vibration throughout the rev range. Take a look at cr500riders.com and see how many others love this modification. The key to this system is the clever shape of the intake between reeds and carby, it is machined alloy not rubber and it diverts a portion of the pulse/pressure wave (when reeds snap shut) down the tube. The tube is a specific length for each bike down to the mm, the pulse is introduced into the carby via the tube just as the reeds are opening. It works at all rpm because it's a loop not a bottle. Jetting setting are much, much richer as far less air is bouncing back and fourth through the carby picking up fuel. I'll never own a 2T without this set up, it simply transforms your engine. I have no affiliation to Ron, just a happy customer trying to say there is some merit to utilizing this pressure wave correctly.

Colin furze brother :-O

We used to use this principle on the exhaust side a long time ago in hotrod building. If your you're running a straight pipe off the header, take a grease crayon and draw a thick line the length of the straight pipe, cold of course. When you start it up, that area where the Helmholtz effect is taking place will heat up first and melt the grease crayon. Then we would cut the pipe just beyond that spot to achieve the best backpressure and maximum scavenging effect. It really works.

Thank you Matt, a clear explanation of a complicated problem.

I had a 2001 snowmobile. I added one and it helped a lot at 6000 rpm. You could feel a serge. On the Dyno it only gave .8 hp Total HP at 8000 RPM.but at 6000 it was 2.6 hp.. the weird thing was under the Af was more consistent and Torque was up 6ft lb at 6250 rpm. I think it did help the guys doing Cross country. But not the guy Drag racing.

The air acts like a spring at a specific rpm range. Mazda's Kl v6 engine family uses this in the intake, helmholtz resonance pricipals. It opens and closes valves to lengthen and shorten the intake to keep tq up through the rpm range. There's 4 different intakes for that engine and an ecu for each that has different open/ close timings. I have all 4, mostly for decoration. You can feel the difference when it doesn't work right, or if you tie the valves open. The car feels boggy, then when it gets to the right spot starts pulling. I can switch ecus and intake to have more midrange or high rpm. An intake that works in stages will work better or several boost bottles that work each at a different rpm. It's called VRIS, variable resonance intake system.

thanks this vid has just explained what the random bottle connected to the inlet stub on my rd125lc was for, always wondered what it did

so i just have to put a coke bottle on the side of my manifold?

I've always heard the bottle needs to be twice the engine's displacement...and the bottles that I made worked very well.

bloomin henry matt, I've said this before you literally have no end to your talents and no limits to your knowledge. You present things like this which is completely new to me, but you always get my brain thinking and somehow over the last few months I know so much more about the science of bike engines thanks to you. You're a flipping guru mate a GURU !!!

first time I've seen anyone else say what I've been saying for years. everyone seems to be firmly in the camp of either "they work they do miracles spend all your money on them" or "boost bottles do fuck all but make you faster by lightening your wallet" "they do work, but not in the way you think, and yours doesn't at all" has earned me a lot of flaming over the years from people who know very little on the subject. even after explaining the actual purpose and the math behind it to people I'm written off as an idiot, even though I have the dyno sheets to prove it.

I had a boost bottle on my RD400, it made it go twice as fast!! And the Micron fork brace, that made it handle like a motoGP bike. And my Simpson Bandit made me look baaadaass! (that last bit is actually true)

When me and my mates had scooters my mate bought one that had been "tuned" and it had a boost bottle and when he took its off and blocked the hole the previous owner made in the runner he was convinced that at the very bottom of the rpm it was considerably perkier I had never seen one since. Great video matt

Yeah I wish the hell I had somebody like you teaching me when I was going to school I can grasp what you're saying you need a hell of a lot higher ranking than what you got . And got a shit ton of material and knowledge. I've been buying up two strokes for the last couple years you know getting all the bad ones from whenever I was growing up 93 CR250R, 89 YZ 250 WR ,2006 banshee, 94RMX250 and 94KTM MXC which I'm in the process of restoring and rebuilding

On a 2 cylinder 2-stroke engine, a "boost bottle" is a bit more effective if for no other reason than being more forgiving of design errors. By tying the 2 intake tracts together you can transfer a high pressure region over to the lower pressure region in the opposite cylinder. We saw modest gains in fuel efficiency in several machines that we installed them in. As far as increase in power though, eh. Not noticeable in any of our installs.

Ok, so here I am, fresh with the glow of having spent a few bucks to squeeze a little extra zing out of my first 2-stroke, looking for the best way to fit it when it arrives. Maybe I can still fit it under the seat to store the remainder of my dignity in. Wanna buy a stage 6 red bull can holder by any chance?

this the same principal of ships and how they part the water. the large lump sticking out of the front makes its own wave and helps mediate the wave it makes anyways. look into it its interesting also! learned a lot here COOL!

so glad i watched this Matt , i was just about to dump the air box on my Ducati to see what would happen and free up room to hide the electrics .........wont be wasting my time on that now. thanks bud.

Thank you for putting forth the effort to show the real science and engineering into how engines work. I really enjoy your video's explaining the real design work into the function of the designs. There are too many shade tree mechanics who don't even understand the basics, but yet they think they know how to improve upon it. Sport engines undergo millions of dollars in research and development to get every ounce of power and efficiency out of them.

Hell hole frequency Had a boost bottle on me Ts1 lambretta 1987,it was well known it did nish ,,but the alloy can and coloured plastic tubes looked dope

If Helmholtz resonation works, these can absolutely work if designed right or the right size is chosen for an application. The effect will still probably be negligible. Wave tuning with independent runners is going to mbe more effective.

You just saved me from buying an expensive malossi boost bottle. You are completely right, on all the products its never specified for what engine size it is or how long the tubes have to be and so on. And on youtube you mostly find videos where boost bottles are mounted on some factory standard scooter by some kids. I think boost bottles only exist because people think that they will go faster for such little money. But in my opinion its, mostly, a scam.

messed about with the boost bottle pipe length on my rd125lc back in the 80's, never made any noticeable difference. ( it always ran at its best with the original airbox on too). 👍

I'm loving your work and the thought you put into this channel!! If you do this topic again you may find that comparing this topic to the topic of the construction of ported sub-woofer (or even better a Bandpass enclosures) topical. Much like an intake and exhaust system, Sub-woofer box construction and design is very intimately related to the sub-woofer being used, the desired frequency range, box volume, port diameter, port length, etc. Since most gear heads probably at one point tried their hand at obnoxiously loud car stereo's and are aware of the variables in involved, it might make a common ground for similar combustion engine topics.

"But this is just a little fucking aperture, so it's just gonna be pissing in here!" Had me dying of laughter! Very good explanation. Keep up the good work.

Thank you so very much,.I never heard of BB,Your a great teacher..Why has the Rice bikes not done what F1 has done with a adjustable air throat? There is a YT video that explains that.Great video,TY73s

This channel is fucking gold.

You can kinda think of the air molecules stopping and starting like being on a 10 lane highway at a backed up traffic light. Light turns green, those in the very front take off first opening a gap with the following vehicles taking off in turn, eventually the 10th car back gets to take off, but suddenly the light turns red. You slow down to stop, along with the cars behind you, going back to bumper to bumper starting at the first vehicle at the light going back, everyone comes to a stop getting closer together. Light turns green, first in line takes off and right after the car behind & behind & behind get to take off. Kinda like air running into the reeds. It’s going, then bam light turns red at the reeds, everyone piles up, reeds open and they take off expanding the gap between them.

holy shit. my brain hurts. I was with ya up till you opened the coke bottle . good video. 👍

My Yamaha DT125RE has 2 "boost bottles" stock.. one before the carb and other before the reed valves. By the way i am curious how cherry bombs on 4 stroke exhausts work! Cheers and keep up the awsome videos comming!!

Hello from 2020 👋🏼

That thing in the lower corner is gonna show up in my nightmares now. Thanks m8!

This was prime Matt 😅👌🏻 miss this whiteboard!

Finaly I know the truth. I thought that this only works on 2strokes and that mixture that gets pushed back thru the carb (because of 2stroke nature) instead gets pushed into the bottle and than sucked into the engine thru the next stroke. Causing more power and greater fuel economy. But I was suspicious the whole time. Thank you for explanation!

As an embedded engineer who dabbles in far too many subjects, I want to thank you for your videos. They've helped me understand how 2 strokes work and how air intakes function. To connect it to my world: intake and exhaust systems are 'transmission lines' with variable 'impedances'. Honestly, air systems for engines seems a lot like designing microwave filters/amplifiers for RF systems. And most Electrical Engineers will tell you that RF engineering is black magic...

I remember that equation from engineering vibrations unit how weird lol

"All" you wanted to know about "boost" bottles - S.A.E. paper on Helmholtz Resonator - www.google.com/search?client=opera&q=S.A.E.+paper+on+Helmholtz+Resonator&sourceid=opera&ie=UTF-8&oe=UTF-8 Also acts as a reservoir to help reduce the distance / inertia between the carb & reed valve. Not only does it give a faster response but without it the fuel-air curve is sinusoidal , going too weak - too rich. With the resonator it changes the sinusoidal curves to a straight line. On my LC350 I got 10% better fuel consumption, tick over picked up slightly & bike carbureted more cleanly.

nice video. been telling people for years those one fits all boost bottles are a crock of shite! but its cool to see the science behind it ive been a powersports mechanic for about 15 years and I learn stuff from your videos all the time.

have you heard of a pulse injection intake system for yamaha yz 250s, does what boost bottles claim . eliminating air reversion in the carburetor, more fuel intake , torque , hp .

I have an rd350 which stays at 2500rpms for 10 seconds before it it idles normally. I have been told to solve this problem by installing 2 boost bottles or a long hose from the left to the right intake. What's your opinion on this? Great explanation by the way!

Jeez, but you're one smart man! Seen a few of your videos now, they're entertaining and informative.

Hey man I just discovered your channel. And I can absorb what you're saying teaching the resonance frequency of the air I never heard it put that way on a gasoline engine but I've been in the speaker boxes and shit for a long time and so I get it I get it exactly what you're saying okay so this is my problem I have a CR250R I modified put it on four wheeler and so I changed my links the distance between the intake port and the carburetor and also the length of the tube going to the airbox which I'm open air and I'm running into acceleration issues so when I throttle it it wants to cut out cut out cut out cut out and then when it goes it's like super fast but it's building up to that point to build the pressure and this just makes so much more sense to me I'm fixing to try something and I'll let you know how it turns out

ah the old Yamaha YICS... ? Yamaha induction control system . had it in my old XZ550.lovely little v twin. shaft drive n fairing did loads of miles on that puppy. didn't light any fires tho but did its job.

hello, I'm Jay... and no wait Y the FUCK did I write and... anyway cheers love your intros! Keep it cheeky mate

To me, there seems to be 2 trains of though when it comes to how boost bottles work. 1) It stores and releases volume for ever stroke of the piston. 2) It stores when you shut the throttle down, and releases the volume when you crack the throttle back open, all dependent on vacuum. I can see small stores and releases for every stroke, but I think the majority of it's work is to give a boost when you crack the throttle back open.

So... It's like a surge arrestor works on your water pipes.

very interesting,all good stuff again

Wow , that was great again ,I had totally forgotten about boost bottles. Thought they went out with the ARC lol , had one on my DT175 Mx in 1986 , paid for it to be put on when I brought the bike , what a waste of money then LMFAO 😂

Great explanation. First class. So in a nut shell, a boost bottle is a shit pressure accumulator. Nice S10.

if the boost bottle was a dynamic entity such as a bladder or spring loaded piston that could respond to different pressure ranges in the harmonic as the harmonic changes with engine speed which is caused by throttle position,fuel flow,inlet depression,reed closure,reed bounce?,all dynamic and at the same time,then like you say a one size bottle wont work,only over a tiny portion of the cycle,which again would mean the bottle must have a dynamic response ,i take it the pressure isn't extremely high,and the "damper" needed is the "bottle",in as much as a rubber buffer absorbs vibration,a rubber bladder could absorb the wave of pressure at the source"reed end" of the inlet tract. Just a thought,seeing as this seems to be a shock wave damper/anti resonance chamber,or pressure brake to have control over a fuel air column ,a bit like a piping bag squeeze get more ,relax get less,not having a back pressure wave counteracting the forward motion of the fuel air column,you want a controllable response,that responds faster,with no lag,not that lag may be humanly perceived,though of course it may. I've had some dealings with resonance,as i am a electronics technician,and why my knowledge of superbikes came into questionin 2T v 4T. What did you think of the dry sump pressure feed of oil to a 2T main bearing and rod/wrist,with mains sealed from crank case being bathed in the gear box,or some form of this to alleviate wear and oil burning for 2T,if 2T can have a small mech pump for 2T oil injection,surely it could be lightly pre-mixed and the pump could lube some form of sealed /separated bearing set up. I would think all the parts are there but in the wrong order on a lot of 2T bikes,and could still be cheap and simple to work on.

okay you save me money lol

I hear and see a lot of people claim all over the place that these work quite well for two stroke 49cc, 77cc and 80cc engines I;ll do some more research though

Well put.!. I could almost she it working in his mind as he explained the mechanism of it.

Ha, ha , ha , I liked this video plain talking , spot on with info , you speak total truth about " harmonics" it's amazing how much they influence engine tuning , I know this with working in motor trade, if only people knew what goes into designing and testing on engines/ gearboxes etc they would leave well alone and lesson the chance of detuning without realising and wasting a lot of hard earned cash

on the website i used to buy tuning shit it said that they would make it easier for the engine to breathe after going off the throttle like for example after a corner.

You are wrong my dear. First: Inside the bottle there´s a soft rubber device with inflates and deflates easily, the bottle is just the case around. When the piston sucks his air.fuel mixture, the mixture will speed up in the manifold creating low pressure. Also low pressure in the bottle. When the piston comes down to press the mixture thru the trans-ports, a little amount of mixture escapes thru the intake and inmediatelly carburator and manyfold will return to atmosphear pressure. But the bottle is still in an underpressure state and wants also to get in atmospheric pressure state, for that the bottle will suck, in this case the bottle will suck the spitted out mixture. Your drawing of the conexion fitting of the botlle to the manifold is not exactly like that. The fitting must have a little diagonal cutted tube witch is screwed down to the middle of the diameter of the manifold section to create a venturi to create sucktion and underpressure in the bottle. Actually for reed valve admission it´s not needed, it´s a very small amount of mixture. But on normal admission valve system very helpfull.

so its better to leave my stock air box rather than fit pods?

Brilliant video 👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍

some cars have them in the intake, to reduce intake drone noise, i believe. 2 examples: Vauxhall Corsa C, on top on the radiator; the 2012 Chevrolet Camaro just before the throttle body

Horizontal slinky is the best analogy for pressure waves; easy to visualise

I had an Yamaha RD 80 with a boost bottle on it (factory build) That realy was a beast for an 80CC engine. It realy works ) Sorry for my bad English.

Thanks dude, I know understand better how the factory boost bottles work on my Honda NSR250. If I understand right, as soon as the engine is modified (airbox, carbs, reeds, volume, ports or exhaust) I might as well plug up the factory boost bottle as I've screwed the factory resonance?

This is some video. Bravo 👍🏻👏👏

I want to know the volume of boost bottle for a 100 cc 2 stroke engine?

I had this work on small 2 strokes with homemade bottles but its hard to get right but some where theres a calculation on the web it will get u close it helped me with low end makes the power band wider but the 1s u can buy are crap but I think they work ok on a 66 to 80 cc bicycle but a balloon in a bottle works better but will not last long I think they work better on a piston port and not as good on a reed valve engine

electronik varible resoant bootle where a programble control of the opening or opening and the inside volum of the bootle-to fill out those dips in 2 stroke?a system like this here the bootle has a piston inside to vari the volum and a sled to varie the opening zize off the neck hvere the presure wawe blows over.a smal el motor to control the piston inside bootle and el controlled sled port to change zize of resonant opening controlled by micro controller with engine input for rpm trottle movement and so on.anyway even this type of sytem need to be made in different zizes to fit different engine volum and so on.sorry for my bad english writting.

I would just try making one rather then buy one at least with homemade one I can experiment with the different size bottles that way

Really interesting vid. I always wondered what they were for :)

if boost bottle doesn't do much then why do many 2 stroke engine tuners install boost bottle on their drag race 2 stroke engines, and why do everyone say that they do get increase in performance after installing aftermarket boost bottle, and i have seen some example where it shows that the fuel was flowing through the boost bottle pipe.

Nice video

you need a slinkie (slinkey?) Just pull it out every time you need to explain what a pressure wave is (longitudinal part). I know its hard to do without visual aid, so instead of a good rant about transverse waves on the beach and a picture of dots in a line... just whip out the ol slinkie. In all seriousness GREAT VID

Thx for the info 👍

Funny enough I’m watching in 2020 lol and you have 76000 subs lol

Hi Matt Interesting video, You are absolutely right when as you explained manufacturers R&D departments get to it they have everything they need to figure out what's what, not saying they are perfect or always right but they are backed up by huge resources and technical knowledge and if you are going to believe anyone it would be sensible to believe those guys! although my area of expertise is electrics I know for a fact that in a given system when you have components connected together if you change one aspect it will have a knock on effect throughout the whole system and one tiny change can result in a massive amount of variables which all need to be studied and understood if a good design is to be arrived at! That said HAPPY NEW YEAR

Seems to me that the problem is that the "booster bottle chamber" isnt expandable. If the chamber can expand at the rate that is needed (wich is probably veryfast in and out), then it will potensially send back unused fuel right? Like in this video : ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-y80MOk3IpSs.html If you use a balloon, without the closed bottle, in atmospheric space, this could work. In my theory at least. But to find the right "balloon" with the right resistant force might be hard to find, at the whole rev-range.

Well I dunno know, I knew they were complicated and I must have got lucky then.. because I could not jet out a horrid CDI flat spot at 6k on my little RS125 after I cleaned up the porting on the head and modded my airbox years ago and after a few goes with chopping the pipe smaller and smaller it's was gone.. needless to say after blowing the ring on it last year and having to swap the head the flat spots back again.. I just wish I was that lucky on the lotto ;) Oh as a side note the reason I had the boost bottle was from fitting it to an RS50 years before and it did f**k all for that bike haha Does make me want to look into this a little more now.. Great channel though Matt!

thank you for the video, very nice. The thing is that scooter riders are young boys who get fooled by all these so called tuners :D

Great video man👍🏽

love your videos man

I used to have a yamaha yz490 and they had this kind of thing on that bike

I definitely agree with your statement about the cheap aftermarket boost bottles, however, the Yamaha systems which are Taylored to the bike do make a difference. I actually plugged my boost bottle on my 04 DT 125 RE as it would Rev itself up and do weird stuff at idle. I rode the bike like this for a few months and I've just put the bottle back on last week. The revving problem at idle was not as bad as I had rejetted the carb for a new exhaust system, I also found it removed a flat spot in my revs which I could not stop, even after messing with jetting and adjustments. The bike has better torque through the Rev range and is a lot snappier when the ypvs opens, I would actually go as far to say it's transformed the bike. And I am usually against all these stupid designs to get a simple and affective engine design to run better, I didn't actually think powervalves were a good idea until I bought the Yamaha, but that's just my take.

liked the video but want to say what about balance pipe between reed blocks?

I'm a bit late but... I have a boost bottle in my Yamaha DT 125 that's designed fir the bike, is it ok to keep it or do i gain power by removing it?

Is a good way to think about these kinds of pressure/air dynamics to think about it as fluid?

Cool vid ! I'm chiming in late but nevertheless... if looked at from a hydronics perpective it's an expansion tank. However, it's missing a presurized bladder. The bladder is charged at a specific pressure relative to the highest MAP expected under full open throttle. The air bladder in the expansion tank is separate from the flow being dampened and will compensate in irregularities in the flow by compressing under the pressure spikes . Also comparable would be a water hammer arrestor. The big difference is that the hydronic fitting uses air to dampen the water because it's compressible and water basically isnt. Without a compressibLe medium your money spent is for not.

I wasn’t expecting that intro... I love it! What would happen if you were to use the crank case pressure as a boost, rather than just a vent? Or is that what they already do?

My bike came from factory without reeds, the airbox is absolutely coated with oil thanks to the mixture being shoved back. Improves the air filter though LOL Some people install reeds on those bikes and claim they have more torque on low and mid-range, is it true? I'm thinking of installing one myself.

Here I though they were just to equalize manifold pressure on multiple cylinder engines. Good to know.

keep em' up mate!!! Love the videos!