Home-made 2 cylinder 4 stroke engine. Part 3 - Pistons 

He'll get away with running it in gently but he won't get away with the scrapper ring, it'll smoke like fook.

4 , 5 , wrong

@@najaciuser5445 explain 5?

The pins have grooves for a E-clip. I am not sure if it will work, but holding thumbs

@@TheXSpitfire please don't do this. you weaken the pin and the clip tends to come lost. the damage will be severe.

Gowipe Yourass maybe all home should have English tutor also

Instablaster.

are you replying?🥺

The stroke will be 30mm and the bore 34mm, it works out to about 55cc total. The plan is to run it on petrol (holding thumbs).... There is a little bit of play room in the compression ratio, but I am aiming to get 9.5:1, that way it is in the middle of safe. It can be lowered or raised by making new pistons. If all goes to plan, it should have a ignition system and single fuel injector controlled by a micro controller like an arduino. I am imagining playing around with the timing and seeing what effect it has on the power. That I dont think you can do with nitro. Thanks for the comment ! See you soon Manish.

@@TheXSpitfire wau nice plan aren't you using carburetor ? fuel injection is better than carburetor? oh oh but a hole for glow plug would be fine and not that big deal in putting a hole when not needed you can cover it with a glow plug with no coil. thanks a lot for your reply!

@@manishpoudel4540 I am not ready to build a working carburetor yet, I simply do not have the skills yet. The fuel injector is relatively simple as its only a petrol pump, regulator and the injector. The advantage is that it will be easy to play around with the fueling using the injector. It would also make it possible to have more than one "map" for the fueling. When it comes to the ignition system and fuel injector I will show my thoughts in more detail.

@@TheXSpitfire oh ok thanks a lot !

Hey. I am going to try an run it for sure. Plan is 2 cylinder and fuel injection. I am going to be shooting the next video the weekend. Thanks for watching. Appreciate it.

With home-made I imply that it was not bought, but made at home. Its not DIY. Home made meaning : Something that is home-made has been made in someone's home, rather than in a shop or factory

Of course some people do have tools. CNC/Milling is a popular hobby. I can make homemade apple pie, even though many people do not own flour.

TDS, My milling machine cost me 130 k all told my equipment is well over a million dollars. I don't think many homes are so equipped...

@@jamesdond1 This video series features a $1000 lathe, and a relatively inexpensive milling machine.

i have a hobby sized mill and lathe in my garden shed, not cnc but i have power feed, i make my own stuff that cannot be bought like gears and drive shafts for rc use.

You are correct.

Duralumin, is a collective designation of a group of high-strength alloys based on aluminum (aluminum alloy) with additions of copper, magnesium and manganese. The name of the alloy comes from the Dural trademark (fr. Dur - hard) - the commercial designation of one of the first aluminum alloys hardened by heat treatment and subsequent aging. The main alloying elements in it were copper (4.5% of the mass), magnesium (1.5%) and manganese (0.5%); the rest is aluminum (93.5%). In tensile tests, the typical value of the yield point of duralumin is about 250 MPa, the short-term strength limit is 400 ... 500 MPa, however, the strength characteristics of a particular alloy depend on its composition and, in particular, on heat treatment.

You should be able to slowly pull on the indicator leg until it reaches the angle you want it to be at.

@@TheXSpitfire thank you very much for your fast and kind answer, but on my micrometer the leg seems firmly fixed ( except for a little angle movement in both directions, for reading purposes ). Pulling has no any effect. I'll try again, thank you in any case. Alessandro from Italy.

Common way to oval and taper pistons is to jack the gudgeon boss apart from inside, machine your desired taper then remove the jack. The boss area will spring back to proving ovalaity. It actually works quite well on suitable alloy for pistons.

@@mikelowe3754 wat type of aloy do you use for the billets i need to make pistons with a 67.5 diameter (been looking at yamaha motorcycle pistons , these seem to fit the bore size though im not quite sure about the placement and size of the wristpin ) going to look intoo ready made sleeves too for a 79 mm stroke hard to search for sumting without a detailed crossrefference list for pistons , wonder if theres sumting out there , in the old days they had the hollander cross reference manuals to see wat carparts fits one wat cars lot of the parts cross over between the car brands

@@watahyahknow I did not machine any taper into the pistons. I was hoping by keeping the tolerances big enough, it will not be necessary have a taper. Hopefully there will be enough compression too. The project is just to learn some lathe skills and if the motor ends up starting...bonus.

@@TheXSpitfire youre doing pretty good , one thing though , lathes are not as precice as you think every time you take the part out and put it back in the chuck it will be offset oh so slightly , try to do all the machining with the part chucked in the same way or work between centers (this alowes you to take out and reinsert the part multiple times) if the expansion turns out to be too mush you can allways put a split in the piston skirt , constructionmanuals.tpub.com/14264/css/Figure-3-25-Controlling-piston-expansion-77.htm good machinist here is abom97 he has some pretty huge machines though and stephan gotteswinter ru-vid.com this guy is a toolmaker and verry exact , he uses mostly chineese tools in his shop though but made better by him through scraping and measuring , i learned a lot from watching him

@@watahyahknow I have made them from T6 free machining extruded bar. Thats the most common off the shelf stuff and cheap. I have made them for fun, not performance. What are you building?

I needed a hole in the back of the of the stock where the cnc router could enter to hollow the piston out. Luckily that hole is not dimensionally critical. The router can machine aluminum but it's pretty slow going and the predrilled holed saved some time.

It looks exactly like it. Just custom stickers of our local distributor. This one came with metal gears and a live centre.

turning them down would be much more practical but the skirt would be weaker.

It’s a yanmar 72mm engine. I could probably use a “standard” over bore. So turn the 73.5 down less than the full 1.5mm

It’s a sleeved engine, the sleeves aren’t thick enough and I won’t run it unsleeved. That would turn it into a throw away block if it even survives a week.

It’s iron, but I don’t feel the solution is to modify the block making rebuilding impossible when you can modify the pistons and rebuild forever.

@@bacilluscereus1299 its diesel engine,not a gasoline,sleeve are best opt

It is a ChinaCNCZone.

Torno Mecanico

Piston apa yang itu

嗨

Hi Sam. I am not quiet proficient with casting yet. In the future I will try my hand at it. It is also an exercise in learning to use CAD/CAM and CNC machining. I am also wondering how long the pistons will last. I want to try a few hardening coatings in the future.

@@TheXSpitfire automobile manufacture add some silicon in alumunium around 15_20% to make it harder and bear temp. High than normal alumunium.

I will be happy if there is carbon build up... It would mean the engine runs! ;p

sharp edges also promote detonation

It will be 25cc per cylinder. It's a bit bigger than I wanted, but the tolerance are easier to hit. Once I know what I'm going I'm going for a micro version.

I have a single overhead cam planned so far. When I get to casting the head I will have to see if it will work or if I will have to re-think the head. As for RPM, I am not expecting anything high as the crank is still not designed as yet. I will have to make the crank in separate pieces to get the bearings on. The balancing of the crank will also be a hurdle to overcome. Thanks for the Speeduino tip ! I will have a look at it. I am hoping to do the block casting next week.

thanks for the link

I decided not to taper the pistons. There is enough play so they can expand, but also enough compression. The motor should start and run a bit.

@Mescalinum Sunshine I am not too worried about efficiency. The gudgeon pins will be from Aluminum too, so the piston should expand more even. The tolerances are at the bigger side of the scale. I had to stop working on the project while things were under lockdown. I will continue next week.

Ek sal dit probeer. Die router loop maar hoë rpm wat maak dat ek net 6mm of minder bits kan gebruik. Ek wil kyk vir mill en dan sal ek jou raad probeer.