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  1. #1
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    Smile two stroke engine

    Hi , will build a 2 stroke engine, it will be a 119 cc one cilynder engine, with intake by the block, in the future i would like to do a 2 stroke v4 or 4 in line, i want to know how the intake is made in that engines. Another question is the water cooling, how do i do the water circuit arround the cilynder in my engine?

    Thank you

  2. #2
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    hi, i wonder what is the problem.... 153 views, no reply, anyonde to explain this to me?

  3. #3
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    Quote Originally Posted by PoWaKiD42 View Post
    hi, i wonder what is the problem.... 153 views, no reply, anyonde to explain this to me?

    Maybe it's just the fact that the 2 stroke is complex in the area of intake design. The port timing is very critical and most people don't do the design work. I would'nt want to try it. Maybe try a forum with engineers who work in that field.

  4. #4
    Community Moderator svenakela's Avatar
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    It's quite easy actually. By using Reed valves you can have big intakes as the piston is not responsible for closing the intake.
    You should try to have an even amount of water all way around, the biggest problems are how close to the exhaust you can have water, and second to be sure that the head gets enough of water.

  5. #5
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    The problem is with a 2 stroke you lose half the combustion through the exhust which includes half the fuel/air mixture so for emmisions its not too feasable. Thats why they have expansion chambers and secondary power valving if you could figure a way to use that secondary gas for power and cleaner emmissions we could sell 2 stroke across the globe.
    Joe
    another thing I used to have a honda replica gp 500 2 stroke bike(kenny roberts) fast as hell and a cr250 dirt bike all the majors have moved to 4 stroke for emmisions? I now have a crf450 200cc more than the 250 thats all they race anymore? the 450 is fast but 450 2 stroke??? I think a cr 500 will beat it on the straight???

  6. #6
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    Probably the easiest way to build a v 4 two stroke would be to use reed valve induction ,letting the engine dictate when it needs to be fed its airfuel mix.The induction system is only the begining of your adventure into making a two stroke engine ,the exhaust port the transfer ports/ crankcase ratio/combustion chamber shape/piston crown shape/stroke/bore.These really are just a few desighn considerations,remembering to the beauty of this engine is you can make it run in reverse with just a change in ignition.A very basic engine can be made with a reasonable amount of knowledge, however if you plan on getting into something a little more high performance some serious home work will need to be done along with many nights of head scratching.Its a great engine to start playing with and im sure you will have a lots of fun with your project,good luck greg.

  7. #7
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    PoWakiD42, If you are in the design phase of this project I suggest you look into "The Basic Design of the Two Stroke Engine" by GP Blair, Queens University, Belfast. Its published in the US by SAE. My copy has been "borrowed" by a "freindly competitor".
    DZASTR

  8. #8
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    For ideas on how to package cooling water, look for fotos of a 4-71 Detroit Diesel.

    Yes it is a diesel but, but it is a two stroke and it shows how to package coolant around the intake port and other stuff. Asside from compression ratio and spark plug in place of the injector, the "basics" are pretty much the same.

    Whether you use valves-in-head or piston porting to do the exhausting is purely an issue of packaging. The book recommendation by DZASTR is a great starting point for 2 cycle engine studies.

  9. #9
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    PoWaKiD42, Another interesting 2-stroke V-4 is an aircraft engine called the Delta Hawk. They are somewhere on the internet, I'll see if I can find them.

    Add: www.deltahawkengines.com
    DZASTR

  10. #10
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    Thanks a lot for the help! i will post some pictures of my solidworks designs, they are not finished yet. Is it to bad that i make the engine air cooled? Is it possible to make the engine with a manual mill? i have acess to a cnc machine on college but its not working right now, it has some programing problems...

  11. #11
    Community Moderator svenakela's Avatar
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    Everything is possible, you just need patience, time and knowledge (or room for errors... ).

    --S

  12. #12
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    If you have seen the older Detroit series of engines as mentioned you will find they are 2 stroke water cooled. Used in lots of applications including boats and other equipment. Locomotives may still have them also.
    With this series the clyinders are wet sleeve. They are sealed on the top and also near the bottom with most having 3 o ring's which is a press fit for sealing. The water circulates around the sleeve for cooling. The engine is also different and more complicated than normal 2 strokes as it has valves for intake and piston porting for exhaust.
    In there day they where very popular but they also had there problems. I have never seen one that did not leak somewhere and if used as a unattended power plant and if they broke the quill shaft you would understand why they called them screaming jimmies. Almost instant destruction with the block looking like a seive from the rods sticking out.
    Retired mechanic,
    John

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