turning the jug

Discussion in '2-Stroke Engines' started by blue 48, Feb 18, 2012.

  1. blue 48

    blue 48 Member

    hi again
    is it possible to rotate the whole cylinder bore 180degrees and will it run?
    i know the goemetry will be unsuitable for a bike but thats not an issue to me. itll be going on a scooter im making:eek:

    i hope it does work bearing in mind im making my own exhaust and inlet.:idea:

  2. motorpsycho

    motorpsycho Active Member

    It should work.(what engine are you talking about?)
    Just remember, this will make your exhaust exit at the rear of the engine, and your carb will be at the front of the engine.
    they used to do this on Triumph motorcycles back in the day for drag racing. Having the carbs in front gives ram air effect.
    I'm not sure if it's just as simple as spinning the jug around, or if there's more to it than that.
  3. blue 48

    blue 48 Member

    hi motopsycho its the 48cc ht, it looks like the transfer ports may be an issue from what im looking at now
  4. Al.Fisherman

    Al.Fisherman Active Member

    As far as the exhaust/intake ports the distance from the bottom of the cylinder are the same (at least on the engine I just measures 66cc).
    But as far as the gasket (transfer ports)...well I'll let you decide.

    Stock gasket placement.

    Reversed gasket

    So I'm going to stick my head out and say NO, as I feel that there would be too much of a restriction of fuel mix supplied to the combustion chamber.
    Last edited: Feb 19, 2012
  5. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    I know of 3 guys that have successfully built 180 rotated cylinder 66 cc
    motorized bicycles.
    I have ridden one of them and the bike runs great. The owner raced it at the last
    2 SoCal Motor Bicycle races and has built at least 4 rotated jug bikes.

    Turn the piston and jug 180 and just match the transfer ports with a dremel
    rotary grinder. That is all that it takes.
    Last edited: Feb 19, 2012
  6. Al.Fisherman

    Al.Fisherman Active Member

    I thought about opening the transfer ports when I took those pictures today. But thought that there isn't that much base thickness to do it. Since you know or those that have.. then he could go for it. If he does, keep us posted.
  7. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Not the best pic.

    Attached Files:

  8. HeadSmess

    HeadSmess Well-Known Member

    yeah, id say its possible.

    better than a dremel, get someone to fill up the ports with weld then dremel for perfection. (like me, with my ali TIG :jester: )

    i wouldnt do it to a HT, too unreliable as they are. wasting 6 hours+ of work is depressing.

    spin the piston at the same time to reduce chances of ring ends going out the port.
  9. blue 48

    blue 48 Member

    welllll.... i asked a friend who does one off casting and machine work for us the same thing

    but i asked if he could remanufacture it from scratch so the transfer ports are the same but reverse the inlet/exhaust ports while maintaining the port timing and size of the origional jug, he grabed his measuring tools checks a few things ,looks at me with a grin and asked how many do ya want !!!!
    so long story short 2 bottles of jack daniels and 3 weeks time ill hopefully have 2 new reverse port jugs coming my way:tt1:

    this guy is great , his work is fantastic and spot on he a retired engine builder and machinist that over the years made some very wise choices in life which saw him with some really neat cars, bikes, workshop equipment and property. he loves the little hts he says theyre the simplest and most perfect example of how the 2 smoke engines work

    camera working now PHOTOS SOON:idea::idea::idea:
  10. HeadSmess

    HeadSmess Well-Known Member

    thats AWESOME!

    you could have the ports tweaked regards shape and size at the same time and make a screamer!

    just be aware that they will need either a CAST IRON sleeve/liner, or chrome plating.

    having experienced chrome plating of alloy, i recomend the liner method.

    if hes good he will make liners, and cast the cylinders around them... :)

    updates required when done :)
  11. blue 48

    blue 48 Member

    i was thinking stainless steel liner thats what i use to re-sleeve brake cylinders i reckon thatll work
  12. HeadSmess

    HeadSmess Well-Known Member

    nah, wrong material. cast iron has lots of graphite in it, remains slightly porous. tis why its predominately used as cylinder material. internal combustion cylinders, that is.

    youll find all your "alloy block" engines still have iron sleeves.

    "stainless steel" is actually a very generalised term. so is cast iron, but hey... any ways, stainless, heat, and rubbing on metal tends to equal failure... remember the piston rings travel up and down the bore 200 times a SECOND at 6000rpm.

    6000/60 =100 times two (up,down) is 200.

    the small alloy cylinders are chrome plated mainly cus its just easier on mass production. saves a few operations. helps heat transfer too :)

    an interesting approach is what theyre doing on the rotaries these days...

    make the cylinder(trochoid...it is a rotor after all) from high silicon/carbon alloy. then heat treat it so that the silicon and carbon combine and precipitate on the surface as SILICON CARBIDE. wet and dry sandpaper, or, the hardest manmade material, 2nd to diamond.

    great, a sandpaper surface on a cylinder? wtf?

    they then get a diamond hone and grind the surface down to size, making it flat.

    theres a slight (microscopic) gap between each silcarb crystal, that helps to retain oil.but due to the diamond grinding, the edges are very sharp. so they then hone out with standard stones, which rounds off the edges without affecting final dimension.

    you now have a surface that cant be chipped off, unlike chrome. its the 2nd hardest material, so it wont wear. it holds oil, so it wont sieze, gall, etc...its always lubricated, and seals better...

    heat treating aluminium...wow. did i say chrome plating it is hard? requires a furnace accurate do the degree that can hold temp for days sometimes... deep knowledge of exactly what alloy is being used (t6 6061, t2 7001, t5 3024, etc...thousands of types)

    just like welding it :D
  13. big kountry 75

    big kountry 75 New Member

    That style is like the old board track racers of days gone by for those guys doing a replica it would be cool
  14. blue 48

    blue 48 Member

    ur right old mate said hes gonna stick with what it came as ( chrome) he reckons not to over complicate things
  15. goodtime65

    goodtime65 Member

  16. HeadSmess

    HeadSmess Well-Known Member

    yep. KISS :)

    read up on porting before he even makes a mold.

    but you can poke the exhaust out anywhere, with a more standard(circular) flange like real bikes, have the carb somewhere else, incorporate enough space for reed valves, everything... even make a :eek: water cooled jug!

    dont forget the head either.

    wish you lived in sydney cus then id wanna meet this guy but then again i guess its just as well youre in SA... :jester: im annoying :)
  17. ChoppaStile

    ChoppaStile New Member

    It will work if you turn the cylinder around, even without the dremol.
  18. KCvale

    KCvale Motorized Bicycle Vendor

    Turn the piston around too, so the rings stays stay with the exhaust port.
    ChoppaStile likes this.
  19. KCvale

    KCvale Motorized Bicycle Vendor

    Not well. The case to cylinder ports don't line up.
    Turn the piston around too, so the ring stays remain orientated with the exhaust port.
  20. ChoppaStile

    ChoppaStile New Member

    Really though. P6220751.jpg