Special Racing Piston = Special Racing Problems. Most Powerful Two Stroke Ever! 

Lots of good suggestions and advice here, thanks guys! I'll reply as soon as I can!

Soon after filming this vid I realized I can probably just stone the lower ring land on all the piston skirts and maybe they'll all work. We'll see. Thanks for watching!

The cylinder warping reminds me of an issue I had with the left cylinder on my Canadian import Suzuki GT550 B, back in the late 1980's. I'd tuned it for drag racing (well they don't go around corners and are nose heavy, handling like a drunk cart horse on roller blades!!) and started to have issues with piston skirts cracking on the left hand cylinder. I suspected something wrong with the cylinder and took it to a tuning shop where they measured it and informed me that it was "twisted & warped". Suzuki GT550 M/A/B cylinders are alloy with nickaseal plating. They contacted Suzuki about it and I was informed that apparently Suzuki made a whole batch of GT550 cylinder castings where the pouring was done in two parts, because they had to top up the pouring vessel, so the casting partially cooled before the moulding was completed. This caused this twisting and warping fault. Nearly all were fixed under a Canadian dealership recall, in the late 1970's, but mine must have slipped the net most likely as it had been exported to the UK at sometime in the late 1970's. I fixed the fault by simply buying another engine for £50 down a breakers yard and transferring a cylinder from that engine.

It amazes me that you are finding problems while in the building/design phase. Tons of shops only find problems by blowing stuff up over and over. Well done, keep up the excellent work

I love that you never have given up on your dream . It is always nice to see what you are doing with this build

Something to consider when you're measuring ring end gap. You want to ensure the ring is perfectly parallel with the cylinder block deck, otherwise your measurements may be slightly off. Easy way to do this is install the ring in the cylinder by hand like what you're already doing, then take one of your pistons and gently press the ring a little further down the cylinder using the piston crown - your piston will be facing upside down while doing this. The result is a perfectly parallel ring for you to measure end gap with less chance for human error. If you're already doing it this way and not showing it in the video, then ignore this comment. Keep up the excellent work.

David Vizard demonstrated the difference made by boring cylinders with and without boring plates in a cast iron block. This was back in the late 70's or early 80's.

First like, then watch

Great video. What you really need is a finer thread in piston top with a good 3 more row of thread. And when threads being made. Must sneak up on them slowly. Also the finer the thread the less canter of the opposing piece. Corse thread. Say a bolt and nut. Coarse thread will make the nut whobble (canter) as it’s screwed on an fine thread will allow nut to not canter as it’s screwed on. Nut in this case is the piston dome(top of piston)

You truly inspire me with your brutal persistence and determination. Keep up the awesome work 👍

Heat treating aluminum, especially castings, can be somewhat of a black art . If there is a sleeve, make sure it cannot move while in the oven . However I don't think it's anymore esoteric than the plating process(s) you have already accomplished .

It’s a very interesting challenge that you are doing. Being an old chap, it was in my time that 50 CC 2 stroke were very popular. The most powerful racing machine was the German Kreidler developing 20 hp, followed by the Japanese and Italian with little less power 18/19 hp. This is a very huge power of 400 hp/L engineers extracted 60 years ago. So, I wish you can do at least the same or maybe better ! All the best to your project.

I've never seen a piston made up of two separable parts before, really interesting 🤔

Nice progress, awesome

very interresting Video Kind Regards form Austria

I once had an idea for a two stroke piston with transfer through piston top that is a valve, thus deleting transfer ports..I did make a prototype piston but after many thought experiments I could see all the pitfalls that lay a head and never proceeded. Seeing what you have achieved over time is remarkable, and Im kicking myself for not continuing my 'Portless 2- Stroke'.

Love the project and can't wait to see the end results! I just wanted to mention that when filing the ring gap you should always file towards the inside of the ring. That way you don't leave a burr on the outside edge of the ring that can scratch the cylinder walls.

Amazing persistence. Respect👍

You can try to mushroom (or cross gash) the threads to create a type of jam nut style threading to tight it all up to avoid having to use Loctite... we do this on some of our Snowmobile bolts to avoid them backing off when loc-tite and ny-lock nuts are not an option. Works well. So in other words, smudge the thread in 2 or three spots, perpendicular to the direction of the threads and that will cause a slight binding to lock the threads once they sleeve is bottomed out on the ring land ridge. Hope this helps!

This thing when finished would look killer with old school engraving. Badazz man!

Maybe the piston expand at the upper section on the lower part when you tighten it together and it is getting hot. And thread the inner part instead for the lockscrew so the outer doesnt expand. And use a taper thread tap (förtapp på svenska) so the screw dont shake loose. Have a nice day.

Top work

Looking forward to seeing it all come together...and hearing final concept at full noise...

Thank you. You're awesome.

I admire your passion and work. 👍 I'm wondering, aren't those pistons too heavy for the rpm which you are planning to push this engine to? Maybe the stress on the con rod will be too high...

Easy is not worth anything then that engine must be worth 12 million dollars. Absolutely love your channel

I believe the reason it is warping to the extent it is, is because the deck and base surfaces are just printed to finish, not properly machined flat and parallel.

Alex, a couple thoughts. First, awesome coffee mug, is that from Pikes Peak? I have the same one! Second, you've got some good ideas already for solving your ring clearance issues, remember KISS will probably always be the best solution for a part exposed to such an extreme environment. I'll jump on the ESE Works thread to share some more detailed design thoughts for future pistons, but they can probably be summarized as: (1) selectable shims for ring-to-ringland clearance and (2) don't rely on the threads to keep concentricity between the piston pieces, use a tighter radial fit on cylindrical sections of each piece. So basically *one and only one* controlling feature in each of the axial and radial directions.

Keep up the good work. Your getting there. 👍

Always a great video, now supporting on Patreon 👍

Ceracoat the top of the piston ...top fuel guys have been doing it for years to help mitigate some of the thermal expansion from the piston itself

fantastic machine work on those pistons!! they must have taken a lot of effort and time to make.

That's great the step will eliminate the play. What about the hole on the ring changed to a slotted hole so the ring,at that point it will slide back and forth which may increase the sealing.

Always good seeing a progress report. I wonder what the rules are on sending Rum to Norway?

The noise is the part of a mekanik/kemi place ;)

You should think of the stress in the upper part that is pressed in one direction by the screw even you make the upper part not wabble that screw remains a stress point, maybe 2 opposite or even 3 in a triagular shape would be better. Its also a solution for the wabble: drill and tap 3 or 4 holes in the skirt like the one that you made and calibrate the upper part ajusting the screws. maybe the screws should be more near the bottom so they have more lever and precision. Its not that good but it could work.

Awesome channel,I enjoy watching Your progress.When I get a Block honed with deck plates they use a head gasket to duplicate a running engine.if You are running a base gasket I would use one when honing also.Just my opinion.Keep up the Great content.👍

Sounds like a perfect job for This Old Tony! He'll knock you up some new pistons, he loves a 2stroke too. Maybe get in contact with him.

I love your content!

I really admire your dedication to this project you like to do my kind of brainstorming a little alchohol and a whole lot of thinking with some machining and you have churned out a whole new engine design I Bet that is how Harley and the Davidsons came up with there first motorcycle. Someday they may make a movie about your journey. Thanks for sharing 👍

I love your Videos!

Hi! I allready wrote to you once. Why dont you try to use a ringless steel piston in a cast iron sleeve? This combination is proved in small model engines. It would be much easy to design your ports and also design the piston in such manner to create a labirinth seal, so the blowby gases will be in small quantity, especially at high revs.

u can tap holes in your drillpress, it works really well

Loctite 266 is made for extreme heat, I use it on the ford 5.4l v8's sparkplug time sert repairs. You may look into that. Just a thought. Great work I'm really impressed! Brings me back to my old days of tinkering.

Before you go making any new pistons, I thought of a way to retain your skirt with a circlip. I described it in a comment on your last video. It might be a worthwhile concept or just get you thinking about different solutions.

Hi, Well done again with all the work, it is great to see how it is coming along. I thought about the shoulder or ring, and I think that despite needing a hard stop I keep thinking if it is sufficient. If the grab screw move the top eccentric, maybe it is worth considering having the internal piston sliding with interference in the skirt. I mean the cylindrical part of the internal piston be tight to the internal diameter of the skirt. This will give you concentricity, and then the shoulder will give you the height. Personally I am not a fan of the side grab screw either, I would put it underneath, but that is purely a personal preference. Keep it up, the engine looks faster and faster at every step! Andrea

Greeting from Oklahoma USA

You can anodize the thread area of the piston to make it grow and create an interference fit (Anodizing thickness is Half below the surface half above the surface). You can also hard anodize the cylinder to make that a little harder to reduce distortion from the honing plates...

Trying times, seems to be the theme of November. Keep at it, soon it will sing like a mad cat!

You could put some marking paint in the inside of the pistonhead and screw it toghether to see where it touches the other side and why it has play/ movement.

I'd consider honing the cylinder while its bolted to the crankcase. Maybe use a spare cylinder head with a hole in the top or just the top honing plate. Use gaskets. Then warm the whole thing up in the oven to normal operating temperature. Then hone to clearance you want. Keep up the great work

I would highly recommend the use of flat, hardened washers under the nuts (or heads of bolts) when installing torque plates (and when assembling the engine as well). Cylinder bore deflection is caused more by the “tipping” movement that is possible on a bolt or stud due to them “digging into” the aluminum and applying a slight sideways force... than by the pure tension the bolt or stud should be applying. That force is also unpredictable (and inconsistent) if flat/hard washers are nut used under the head or nut.

Design a squished shim system to fit inside your ring groove. Precision wire might serve as gap stock... possibly arranged like hour markers on an analog clock face. Just thinking and my thumb started typing.

Please gas port the pistons to help with sealing!

Heat treatment does not change the stiffness of the metal, if the bolts are overtightened in a soft material there will be plastic deformation, given you use an O ring and a lot of bolts they do not need to be that tight. A quick test would be to lightly hone the cylinder to ensure a round bore, measure it then install the torque plates and measure it again. Remove the torque plates and measure again, if the last measurement is the same as the first then no plastic deformation has take place and heat treatment will not help. Take 2 measurements turning the micrometers 60 degrees between measurements just in case the bore has 3 lobe distortion. Putting a bit of mark out blue on the piston and sliding up an down the bore a few times will give a good idea of the skirt contact. With those new rings it should be possible to use a normal piston and machine a pocket to clear the pin in the back of the ring groove. A sinker EDM would do it easy failing that a reground woodruff key cutter would work.

Maybe run four set screws to stabilize the two piece piston. At 12-3-6-9.

Nice

conical conections are good for acurate and secure locating, if tighter manuf. tolerances or limited interchangability are aceptable

if it's loose, try put some washer made from extra thin metal inside, maybe it will help, idk im not engineer, but it's worth to try

Alex, you can solve the skirt problem installing 3 screws, located in 120 degrees steps.

Could you make thin shim washers so that the inner and outer pistons lock up at the right point to give the correct ring clearance? OR. Lock the two piston halves together and put the assembly in the lathe and machine out the grouve to the correct clearance. Rusty from downunder

Awesome work as usual. You could be a clockmaker! To harden the casting you could also dip it in liquid nitrogen I believe. Not sure what the process is called (cryogenic treatment), but I know it's been done on (race)car engine parts to harden them out.

Maybe outher shell piston (crown, ring seats and skirt) with screwed in part with wrist pin? Should solve clearing issues, altought locking the ring and skirt is still a must.

Can you make a small (narrow) ring shim for the first piston that achieves the same outcome as the ledge on the second piston? Thanks for the great content!!!

Teflon tape on the treads of the poston/skirt to take up gap/play in the threading.

Has the thought of a ring assembly ever floated by your shop? A separate stacked unit that has all the features in one? I'm still waiting for the details to present themselves...

Be careful when using a grub screw like this as it may jack your piston skirt off to one side making it oval, we use a similar technique at work but would have a through hole in the skirt then a blind tapped hole in the part housing the little end bearing, the other option would be to use a dog point screw which doesn't pass fully through the skirt.

Heat treating the cylinder (or any aluminum part) will not change the "stiffness" of it within the elastic limit.

u can tap holes in your drill press, thats what the pros do. it saves time, and u are sure the tap is straight to the hole, wich can bedifficult, specially if u tap

Watch you bore micrometer. I think at 2:50 it went in slightly angled. We used to wobble them and get a nice scrape. And check your adjustment on how tight you make it. It looks tight. I could be wrong. That happens.

yes please

Maybe shims would help you get the right groove height and tighten up before you lock it with the grub screw.

try a soft coating on your pistons wearing away while running. i think the perfect geometrical match at operation temperature is most important. Than you can run without piston rings like a RC engine. Also a much oil helps sealing the combustion. maybe 1:15 oil ratio.

And use shims under thread land to set pist ring gap so it’s evenly touched down all around

You probably already know this but I've seen Pistons with a pin in the ring Groove to keep the ring from rotating, of course you would have to file the end of the ring to fit the pen

Your cylinder with several inlaid vertical ring guide pins of Trinium alloy would allow a regular piston and rings to be used for testing. A suitably tough material could be thin enough to perhaps not affect your flow too much. I forgot that the Trinium mine planet buried their stargate. The planet I recognize out our front window has plenty of Naquadah. Maybe a trade?

Привет с России. Greetings from Russia. Thank you for the video. I've been watching you for a long time. 👍👍👍👍

Just an idea: I don't like the grub screw screwed into the sleeve. It could push the piston's top-end ever so slightly out of allignment with the piston sleeve. I'd tap the threads into the top end of the piston and either make a grub screw out of a m3 or m2,5 screw by grinding the head into the diameter of the thread, or make the hole in the sleeve as big as the screw's head.

Could you add three more grub screws in a cross pattern + to stop the movement have just one causes wobble adding three more should stabilise

Hey 2STROKE STUFFING do you recommend 70-80cc 2t kits with 1 pistong ring or 2 piston rings.

Try Teflon tejp on the thread should eliminate the thread gap...

Hey mate the ring land doesn’t need to be right at the join. Or dose it?? Have a standard type ringland below/above the piston join, the ring locator peg can be trapped in a hole when the 2 piston parts are screwed together. It will save the extra comlecations! Those ultra thin rings will be harsh on the bore and ports. Keep up the good work 👍👌✌️🤘cheers 🍻

I can see future issue of the combustion compressing the piston crown over time slowly squeezing the ring. Put it together and check. Then smack the crown with small dead blow. See if it compresses.

You also might want to heat the piston in boiling water when setting ring clearance and set hole. Include the ring as it will expand less.

Harden @ 520-530°C for 3-6 hours. Cool water quench only, as polymer quench won't give the same hardness. Age at 150-175°C for 6-10 hours.

on the piston that doesnt have a step on it you could put 4 set screws intead of one. one every 90 degrees that way it stays aligned. just a thought

As I said earlier, the piston ring may ultimately end up taking on the appearance of an internal circlip, with the 'plier holes' in a ramp form engaging with pins mounted in ring groove on the opposite side to exhaust port center.

Perhaps already said, Just skim off as necessary for clearance you want. :)

Ive tried fallowing the build but ive got s few questions. Arnt you concerned about the set screw backing out? Also that piston seems like it would be really heavy and alot of max for such a small engine and high rpm's? Just curious.

Correct me if 2 strokes are different but honing with torque plates on water cooled racing blocks is done with hot water to get thermal stability in the bore.

did you make that piston? seems like i want that too for my scooter . may be you can explain in another video about what is the advantage of covered wrist pin hole.

for cooling the casting after heat treated don't used water use mineral oil or oil not water because it can crack the cylinder for the thermal shock

off topic but! when measuring length of port as part of header pipe, do you measure to the top edge of exhaust port to the flange?

Some advice on heat treating: don't do any machining before the treating, you will warp the block and every machined surface Once the heat treating is done, machine the parts

Just an idea. To get more Patreons so you can do this part time or full time. Try showing the Patreon logo and maybe the names of your Patreons, like you have done in some videos. It can be real quick just a cople of seconds scrolling the names four or five names per row. You can do a voice over so it dont get boring for non patreons. It rubs peoples egos to see their own name and will probably get you more people donating. And also it reminds people that you have a patreon.

More set screws! :D

Dude, once it clicks, it's done. Done over-click it. A click is a click. Have another beer and...well, no, don't do that.

07:40 Noch nie so einen Kolben gesehen. Never seen such piston before. Irre! Amazeing!

Could you machine the lip onto the top edge of the sleeve leaving just enough space for the ring to move? Basically if you don't have enough step on the piston top can you "add" it to the top of the sleep to make up for it?

So many dynamic forces in a complex part like this during heat treating... Not sure if there's enough material movement on a part this small to be a concern, but I imagine that the quench could cause stress fractures in any weaker areas, voids, or thin spots. Not that it's practical, but would pouring the casting and throwing it into a vacuum and cooling as slow as possible help if heat treating proves destructive?