Found where Power is Hiding, Destroyed Engine along the way... 

Maybe a destroyed cylinder is a blessing in disguise. Seems with all the port errors maybe a reprint or new casting would be a freash start.

I might be in love with that Triumph!

The gearbox transmission pulley system is a huge uncertain factor in any case but if you loose like 40% of the power from changing the pulley, it must be ALOT. Keeping in mind it makes as much as the death trap on this dyno with all those losses is good news really. Is there any chance you'll refit the engine to the load cell dyno? Maybe change the brake to a hydraulic pump one, like "Tvåtaktsmeken"? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nn8d7jHnGP4.html

My man, please make the exhaust port round/rounder into the exhaust flenge instead of the giant oval

I did watch your torque figures (max. 5.6 Nm), since (for the same intake pressure efficiency) the engine takes the same amount of energy each stroke. So, at a given RPM, the torque tells, if the cylinder is filled properly (if ignition timing is kept constant). This is good to compare, which pipe gives its best resonance, and at which rpm. Btw, the KX 60 has 9Nm of torque, so 7.5 from 50cc seems achievable. Of course. your design lowered it, to be gained back on increased RPM. Based on the KX60, 12.5 hp from 50cc is a good baseline, which you allready have, around 16000. I wonder if the torque at 16...18000 could be raised to 6-8 Nm by better gas-dynamics and pressure waves.

Exciting times!

Maybe you could try a cvt clutch system

I could feel you were close Seems like you always have something happen right at the last second

Arg ring snag. It feels the engine is more likely to be in the 16 to 18 HP in reality 👍

When my scooter snagged a ring( the upper one) it was dying for a couple seconds then i got power again and was working until i stopped after 100m it just died

Assumptions are the mothers of all f**k-ups 😅

Is bhp lost through a loose chain, myth or truth?

What the goal here? 30-35hp N/A and 50-60hp forced induction?

We ALL... felt your pain at the end...all that running and then..NOOOO ring snag!!! 😢 We're all behind you and really now looking forward to the next instalment. Good luck and keep moving forward....

What I keep hearing is the cylinder is not what you think is correct. You keep trying to work around the cylinder issues. Time to make a proper cylinder.

Great episode and finally the best quote from you for a while Alex.." Stop Assuming". You went step by step and test by test this episode to determine the factors affecting the power output. Having watched your channel for 4 years this is a major step forward for you and your stubbornness! :-) With all the knowledege you have now, it seems next step is to design and manufacture v2 of the engine fixing all the workarounds and mistakes you have found in the first one. Attempting to fix this one and then start working on the dyno seems a redundant step. Take the time with a new design and while thats getting manufactured work on fixing the Dyno setup with another engine. Im sure we could all give you some money to get a new cylinder printed or cast. I see great things happening soon!

The ring snagging is unfortunate but I feel like you've come a long way, found a lot of issues and learned a lot over the last few weeks. That's all valuable knowledge and experience. I think you need to keep going down the path of simplifying things and removing as many variables as possible. That seems to be helping a lot. Hopefully this setback can be turned into an opportunity to correct the cylinder/port design mistakes. Best of luck. 👍

On the belt loss conversation, if that tensioner is made for automotive timing belts it it likely not intended to run the surface speeds you’re putting it through. If it is a gressed bearing it’s likely adding a lot of loss from grease sheer.

Hope your son gets better soon! Happy about the proress on the bike! :)

You've certainly come a long way in the years I've been watching you Alex. I'd be tempted to recast the the cylinder yourself like you've done in the past. But instead of nicosil coating I'd insert a cast iron liner. In addition I'd making the transfer ports all 3d printed inserts, this way you can simply adjust the port angles by printing new ones. Good luck with it all and best wishes

Mate, you have good success with 3D-printed transfers. Why not make a cylinder with huge transfers then stuff them any way you want. Just sleeve the cylinder so you can match the ports for every transfer stuffer you make? Would make experimenting with port hight, shape and angle a lot easier.

This content rivals the attention for my gf... keep it up beother!

The situation seems dire to me. Until you get your torque/bhp measurement problem fixed, nothing else you do to the engine will matter. By the way, testing 45 and 70 bhp (at the wheel) motorcycles doesn't justify your dyno's ability to do the job at much lower torque/bhp numbers-as you learned at the end of this video. Sorry that you have to start over again with your cylinder, but you seem to be on the right path with the projected time-area numbers for the ports.Please spend whatever time and (unfortunately) money necessary to obtain and set-up an engine-only dyno, such as a simple water brake-even if you have to retrieve the data manually at set rpm points throughout the power band. Best of luck, I'm pulling for you!

Oh look, another emotional rollercoaster from 2SS

Are you trying to tell the world that 203 in exhaust duration is good for 25000rpm? I´d say you need to not trust what Engmod is telling you, there is no laws of physics in the program that sets up barriers. I´d say you also need to port the transfers to about 136-138 having that much exhaust duration, and i am being restrictive here, there are old gp bikes that were running 205/140, and they still pulled hard 'down low'. My experiances is when having insane exhaust duration with low transfers is that yes it will rev, but make no good power.

3rd time I'll leave this message. Put a MAF on it just to see when you're drawing more air. You've got too many variables and no data as to whether it's drawing more air when you change things. You can remove the MAF when you're satisfied with flow.

For your testsetup: What about a puch e50 style gearbox? Only one big gear connected to the clutch basked directly connected to the crank. If you used a dry centrifugal clutch with stiff springs, you could also rev the engine higher before engaging with the wheel. If you could make it so it takes oil would be ever better, but a lot more work. Its a simple design that might work for you, but you lose the upside of being able to switch gears or have a variable transmission, it would be a direct drive system with almost no losses I think.

Other everlasting TV-shows like Grays Anatomy make a musical episode. When will we get the 2 stroke stuffing musical episode?

I'm not an expert by any means, and i don't know the correct terminology here, but surely it would be better to be using a dyno that connects directly to the engine, (a bench dyno?) Measuring HP at the wheel will never tell you what the engine is actually producing anyway, plus all of the extra headaches of dealing with the transmission, constantly taking the engine in and out of the bike etc.. It would free up so much time for experimenting that is lost in the labour of testing it in a bike, and is giving totally inconclusive HP readings.. I race karts and none of the engines, either 4 or 2 stroke, are ever measured at the wheel. A Rotax Max 125 for example is rated at around 32HP, but that's on the bench, not at the wheel. Small engine Dyno comps popular in the US are all measured on the bench too.. I'm just curious as to why you persevere with the bike..? It seems to be such a hassle and an additional hinderance to your progress.. I for one would much prefer to see more experimentation with the engine, and hence more dyno runs, than constant wrenching on the bike.. I love the videos though, i haven't missed one for years now, i'm just giving my two cents :)

29:39 - IS THERE ANY WAY that you can replace the belt drive (from the motor to gear box) to a gear driven system? 🤔🤔🤔 😎🇬🇧

Thanks for checking transfers and blowdown. I can't wait to see how it performs! Good luck Alex

ever thought about a long intake trumpet ? incoming gas has mass / velocity therefore inertia ! creating a positive pressure for when inlet disc opens . Inertial ramming ? Heath.

Ya gotta swap those belts out for a chain setup Alec, cut the driveline losses by 85 to 90 percent. I know it’s messy and a pain in the ass but we’re going for gold here boss!!

The dyno setup is, as noted by others, an uncertain factor. Just brainstorming: as an electronics engineer I was wondering if there is another way of building a dyno with an electric motor used as a generator driven by the crank, motor driver and some amount of battery storage or load dump resistance. Torque than cannot be derived from inertia, but with a torque sensor in the axel it could be done. I also feel a new T-shirt design coming: "Assumption is worth nothing"

I’m sorry, but I’ve been saying all along that parasitic loss is a major issue, especially on an engine this small. A new set of custom billet cases is in order no? 😜

what about a shorter rod? or possibly change the wrist pin location on the piston? maybe case stuffers

Could you leave the display box with the hp and tq numbers on screen for a few more seconds? My old eyes aren't fast enough to read what is on the screen. TIA s.r.

Try to make sure your son gets good physical therapy and maybe some chiropractic work on his shoulder. I dislocated mine when I was 2 or 3 and everything was fine until my late 30s, but now my shoulder is giving me problems and I think the genesis was that dislocation so long ago...

Every time i get in here, i keep saying the same stuff... YOU NEED AN *ENGINE* DYNO! Hopefully now you understand why i say you running through the gears gives you JUNK DATA... It also adds a ton of variance in your day to day tests.. ELIMINATE THE VARIABLES and make an engine dyno!

Assumption is the mother of all mistakes....

Why are you doing motor development with the motor in a bike frame and using a gearbox which is probably robbing a lot of power? Seriously??? Why not mount the motor to the dyno frame and use an intermediate shaft and belts driving a rear wheel on the dyno drum and adjust the pulley teeth counts to emulate the gearbox reduction and get the wheel rpm to a range that is acceptable. Once that is done, LEAVE THAT SECTION ALONE... DON'T MAKE IT YET ANOTHER VARIABLE THAT YOU NEED TO CONSIDER ALL THE TIME WHICH JUST CONFUSES EVERYTHING... Possibly use a planetary gear set out of an automatic car gearbox as a clutch and tighten the band with a lever to "engage" drive to the wheel. Then at least you will have a stable test platform and you will be comparing apples with apples. In addition, it would be easier to work on the motor WITHOUT taking it out and MOST IMPORTANTLY the guys that follow you will not have to look around bike frame rails and under fuel tanks to see your masterpiece. With a proper "test bed" that is not robbing who knows how much power in any particular setup configuration and remains low drag and low friction you will be in a better position to spot the changes that really make a difference.

It seems like all signs point to cylinder with all other major potential problem areas tested. Starting with a proven cylinder design, then modifying from there would remove the reoccurring problem of too many variables being tested at once. Problem solving is going to be incredibly difficult with multiple variables/experimental designs in each test. Best of luck, this is channel is consistently putting out such great content!

Two things have bothered me since the beginning of this series. Cylinder scavenge & primary compression. Simply more x-sectional area in of itself for exhaust & transfers doesn't equal better scavenge. The flow characteristics do, curious if the top of the piston gives u evidence as to how that scavenge is working. Direction the transfers send the gasses , how the cylinder fills etc. all adds up. And primary compression to create the velocity up the transfers into the cylinder. SO I have to assume you have designed around this. Your knowledge far exceeds mine, but the "feel" I get hearing that motor run has always reminded me on one with either too much case volume or intake duration. For fun & games my 70cc Husqvarna build has the blow down in the 20--22 degree range for power in the 10-12,000 rpm range

Misschien is het dit, misschien is het dat, maar als je de basis principes van een tweetakt negeert zal het nooit wat worden met z'n warhoofd. Als je krukas ruimte te groot is zal je nooit genoeg aanzuig kracht hebben om voldoende brandstof in de krukas ruimte te zuigen en ook te weinig kracht om de brandstof in de cilinder te pompen. Kijk eens naar een tweetact racer van een japanse fabrieksmachine , en ook eens naar een nederlands tomos 4l blok waar een extra kamer aan de krukas ruimte is toegevoegd om te voldoen aan de nederlandse vermogens beperking.

With all this changes you'd really need Factory Optimization to make any sense of it.

About bloody time you found it.

You should maybe make the cylinder fit on an existing crankcase, like the AM6 to minimize transmission losses.

You could here what sounds like a supercharger 'whine' on the last runs. That can't be good if it's coming from that belt system. I think a new cylinder with a liner should be next considered. maybe try a few port jobs. Keep up the great work! From your everyday biker that dreams of doing what your doin in my own shed 😎

To lower the exhaust part , just remove needed height from base of cylinder, then correct your transfer height to your desired height … also correct cylinder head volume. From what I’ve seen you do ,this would not be overly difficult.

Maybe time to try the engine dyno again? That simple RC low-pass filter circuit should clean up most of the load cell noise, so if you can get the speed signal cleaned up you should be in good shape. Maybe try MAX9924 with a VR sensor as your crank speed input?

Try checking out Rockey mountain chainsaw thy make performance exhaust pipes for 2 strokes😊😊

Are you going to take advantage that the cylinder is scratched to raise the transfers? I think its a good idea since you might need to plate that thing…

Smaller exit on exhaust maybe?

Alex there even a long way to 1960 HP, Ask chat gpt what to do 🤔

It's the fairing, change the fairing.

Reads title immediately gets depressed 😢

Regarding the losses. Ofcourse if you change the gearing, you´ll see less HP at the wheel, because higher speed means higher losses. Does the power change if you run it with the bigger pulley, but with a lower gear, so that the rear wheel speed stays same? Or plot the power curve hp/kph, not hp/rpm.

Hi alex...try this porting...17mm exhaust on the top is 209°..transfers 28.5mm on the top cyl..is 141,41°.....34 blowdown...18k

Searching ! Seek and Destroy ! Metallica 😊

I just wasted 35min changing the carb setting on my enduro for it not to start afterwards and then wasted more time. To then go back inside, see your new video, and feel better as I didn't feel as lonely in my 2 stroke suffering lol. I don't know how you do it man.

so the exhaust pipe has a frequency response as an organ pipe, something between 20-20000Hz, well if you expect 15kHz of the engine, then the pipe has to pitch up to that same 15kHz tune. maybe a pipe resonant analysis device separately could be nice. well rpm / 60s = revolutions per second = Hz, so 15000rpm / 60s = 250Hz exhaust pipe tune, thats a pretty low pitch tune. thats pretty much a tv test tune pitch Hz lol. note: tapered piston cylinder ignition section would take some initial force from the cycle btw, because narrower initial piston/cylinder combustion pressure area. rip engine :)

Wishing your son a quick recovery.

If there is a CV-joint capable of 20k RPM why not mount the engine inline with the AM6 shaft (the driven pully you have). It would make the engine a bit easier to work on as well I guess.

How come your pipe doesn’t have a stinger? I use a FMF silencer on my Honda Dio pipe as the stinger. It’s like a vertical Jog pipe for my hybrid Minarelli engine and it turns over 15,000 rpm’s with me on it , that’s under a load with the wind in my face. It didn’t do that before with a 4” stinger that I think was to small. The FMF Silencer came off my Franco Morini Motori 60cc water cooled engine. Now my Franco Morini S5GS 50cc needed a 12” stinger 1/2 the diameter of the engine exhaust size coming off the cylinder. Maybe your transfers are not high enough for the rpm’s your trying to turn. Try a slip on stinger it can’t break what’s broke,,,,,,

1/2 way there - My 50cc bike is home next week and will get ready for Aus Speed Week in March 2024. Chasing 105mph

To TEST if you are loosing power in the Belt/Bearings/Sprockets then just LOOK at them with a Thermal Camera to see IF and where they get very hot. Loosing several HP all in 1 place is a LOT OF HEAT, and that energy should show up quickly and easily -> exactly where it is being lost.

Funny thing, I've watched enough of your videos that it seems to me I can hear a difference in the way the engine runs when it's making more or less power. And it sounded reasonably healthy on that last run - like it should have been making 12.5 horse or so I'm just not seeing why a change in primary drive ratio should have such a big change in horsepower In "THEORY", you should just swap torque for RPM at the roller with the gear change Unless there's some kind of drag in that gearbox, that gets worse as RPM goes up? Think you might be onto something there...

Just found your sight, love it, I'm 50+ year lover of everything two stroke, but of course bikes are number one(dirt and street), outboards, model airplane engines (RC), chain saws, you name it. Love the smell of caster oil...the real stuff. I've done a lot of research into two stroke modification, modeled some port work with our CAD CAM and finite element software off hours for fun to try and get more power...but good ole trial and error sometimes works the best. I don't have access to a dyno, so its all seat of the pants stuff and timing. I've holed many pistons and broken countless rings snagging a lip. Have a crunched up Kaw H2 engine right now that broke a ring due to somebody else's lousy port work. Great videos!

ummm A SUPERCHARGED engine with ONLY 64 hP??? Go buy a Ducati and strip it....

How much impact small changes in port dimensions and position have is just unbelievable. Maybe you should look into a chain primary drive if you can't get a direct drive, a chain has less friction than a belt.

I do enjoy the way that in half the sentences your brain keeps overtaking your talking. If you need to be quite that precise with the ports are you considering an iron sleeve? Seems like one way to have a CNC produce it incase you want to illiminate the human error. Iron won't last forever but "testing purposes" See you next time

With the high loss from the Belt, you could probably replace it with 2 gears, one on the crank and one on the jack shaft in the am6. the other variant would be to cut a hole in the am6 clutch cover and run a crankshaft sprocket to the clutch assembly of the am6 direktly (i dont know if this is possible with your crankcase size, it might require cutting the Am6 Crankcase off, just keeping the gearbox half of the am6.) Best regards from Germany and best of Luck!

If you could manage to have a trombone style exhaust, you should be able to change the pipe length according to RPMs. Get that sonic barrier to be timed shorter as your engine speed increases. I realize that is entirely outside of the blow down and transport issue... Well... Kinda. They work together dynamically and synergistically. It is not an either/or, but a 'both' type situation.

Where can I get the programs at 18:00? :)

something curious, the 1983? Honda Fc50 beat, its an Af07 engine, theres not alot of infomation about them either, its factory about 8.8hp, which is a ton, and it uses a foot operated power valve (V-Tac), ive done a rebuild, and basicly how it works- exaust gas leaves and does a right angle out the exaust, upon opening the valve, gases can now go straight and also the orignal path, making twice the volume move which is a big power thump...i have a spare engine here if your ever curious and want one sent to you for trial and error purposes

Ouch! Could this be the time to design another cylinder with your ports setup "just right"?

The software model...seems very optimistic.... Since you can measure your non ideal condition ...if those dimensions were inputted does the software predict 13 hp..?

raising the ports to 139 will give you a blowdown of 32 degrees whit that exhaustport, 133 mean 35 - still a bit to high in my opinion - 128 is 38 degrees blowdown - well that's really off in my head atleast

You need to stop jumping around . Test and change ONLY ONE parameter at a time. Just in this one video you have jumped from pipes to port stuffers to intermediate drive and all the time changing timing and under inconsistent loads. What RPM do you want the engine to run? And what load do you want to achieve ? How many gears does your transmission have?

Have you looked into the Aprilla RS50 that made 27 HP ? And possibly adapt some of that technology to your engine . Just a thought 😊

It would be best to dyno some lower hp bikes (10-20 hp) instead to see if your dyno shows about the same numbers. Those two bikes are too powerful to compare with high hp 50 cc. Your dyno might show correct hp numbers at that power levels but not be correct at smaller. Or is there any other dynos near your location so you could do some comparison dyno tests there? Maybe it’s best to make a completely new cylinder to get rid of that too big exhaust blowdown problem.

"Assume" - makes an Ass of u and me. Wishing you and your family a happy and successful Christmas. Lots of progress imminent I feel.

If you want to peak at 20k, it seems the pipe would need to be 80% of the current short pipe length.

I think, engine worked properly, but for higher rpm., primary w belt take a lot of power. Maybe chain better...IMO.

Excuse me but I cant help but think that AI could probably help design quite alot in designing a perfect engine. Although I realize that may not be the point of this effort. Nice job

Nu kör vi igen

had tested on a dyno in the past that a normal variator belt and a kevlar the kevlar "stole" a bit over 2HP on just the same engine in the stiffness and friction loss. also the rear rim its a heafty piece that weight almost twice as much as a 17" spoked wheel and that is also lots of rotating masses. tyre is the same where a normal moped 17"/120-130mm got some major weight compared to a 120/17" racing slicks.

One thought to eliminate the belt drive. Since you are using case stuffers on the large pip chrankcase and secondary intake. Would it be possible to put the pip cylinder on the am6 chrankcase with a adapter for the boltpattern and transferports of some sort? Useing a chrank with the same stroke and rod lengh. Maybe machine down the deck of the chrank case or the cylinder to make space if needed. There wouldnt be any unknown losses anymore. One could also test a reed intake and then convert it to rotary valve. Is the chrankcase volume big enough on the am6?

I wonder what one of those hollow plastic boxes between the carb and intake port would do. My old Yamaha dirtbikes didn't like them removed but not sure what in the hell they really did.

so would it be worth using a high ratio to get more torque going into the trans, and decrease the final drive so there is less oil and air resistance with slower spinning gears and shafts? or maybe a direct drive 12T: 440T gear set lol i don't know much about two stroke porting, but with a very wide port, couldn't you hold cylinder pressure longer and still get it to blow down, pull a fresh charge in, seal transfers, and re pressures from the exhaust pulse much faster? aka less duration with a much shorter pipe than "normal" to match. id say the transfers would have to be closer to the top the the exhaust port as well due to the speed at which it can dump exhaust gasses. that alone though seems like it would make reversion bad. maybe a tesla valve or a reed in the transfers.

This video is a reply to all your comments.... exhaust.. dyno.. good work man

I think it’s possible that the large differences in transfer and blowdown time area is causing some problems. Bc yes the transfers aren’t a limiting factor but the overly large blowdown will hurt cylinder filling more than what’s necessary(and more than what the transfers are made for) and i think this problem is made a lot worse if the pipe is acting up(im not so sure on the pipe acting up bit) and not “sending” the pressure pulses at the correct time restuffing the cylinder with escaped gases.

Saw of the crankcase and weld your crankcase case to the gearbox using a spacer to align where they split. Crank to clutch should be no problem.

I suggest a very fine pitch chain for the primary reduction and a reasonably big reduction. Belts are lossy. I have had very good results with high speed chains.

In psychology, contradictory observations leading to assumptions leading to actions, never have good outcomes. So if you can eliminate all your contradictory observations and base your actions on compatible assumptions, good outcomes are almost inevitable 👍

This video was a heavy lift to watch, so I know it was a brain drain for you to produce. However, I do think the wreckage at the end is a sign from the gods; it's time for a new and corrected cylinder.

Were those dino runs running a calculation for engine rpm or were they getting a tach signal from the engine? If it was running a calculation for the engine rpm that might throw the hp off in the software when you do pulley changes. I'm sure you already know that, just spit balling

Back to engine dyno

Very good outcomes by this testseries it seems to me. Even though the not very neat ending with a snapped ring. I would suggest to have the clutch as close to the crank (in power travelling terms) as possible because then you can measure the losses of the chain and gears while the clutch is open and the dyno wheeling down in rpms. Keep up the freaking awesome style and content!

Groundhog ďay...