Discussion in '2-Stroke Engines' started by teamgorillaracingTGR, Aug 7, 2008.

  1. ive been looking at a whole lot of the threads here, and from what it looks like is these engines are gutless? do you really need nitro?
    have any of you looked at port timing? blowdown?
    run only one ring? porting?
    im sorry but i was going to buy a kit for a schwinn occ chopper and by the looks of it none of these kits sound like a real two stroke. does anyone know if there is any aftermarket performance parts for these? my friend had a 48cc kit and he ended up selling it on craigslist cause he can only get 18mph out of it. so if i buy a 48 kit what can i do to get more performance since bieng in seattle which is known for its mile long steep hills im going to need every thing i can get
    thanks in advance-TG

  2. lildeezul

    lildeezul Member

    Yeah , you can port and polish them, Change the duration and ect. If you raise your exhuast duration our powerband will move further in the rpm range.

    Also there are expansion pipes, ( looks like a 2 stroke pipe_) can that go on these engine.

    Go to the WILD IN THE STREETS section of this forum
  3. sure. from what i hear thes motors have horrible port timing and blowdown and cant take much abuse
  4. Ghost0

    Ghost0 Guest

    Here are my suggestions in order of importance.
    1. Match intake and exhaust manifolds to the intake and exhaust ports on the cylinder. They typically are round hole square peg set up in the stock configuration.
    2. Tuned pipe, if you have to spend money this is the first step.
    3. Carburetor, you can tune the stock one correctly by jetting and playing with the needle and it will work fine or you can get a good after market one.
    4. Porting, changing intake and exhaust port timing in the cylinder to improve breathing and increase rpm.
    5. Gears, if you can alter gear ratios it make climbing hills and cruising at higher speeds much more attainable.
  5. i know all that lol but i want to know if theres anything like bore kits stroker cranks just the works

    just look at the engine in my pic! ive built 33 others like it all china pocketbike engines too and a few goped motors but these 80cc motors sound like they would have a hard time keeping up to a stock pocketbike motor!
  6. loquin

    loquin Active Member

    Well, the "80 cc" motors are actually 69cc... Otherwise known as EBay inflation!
  7. lol and my "49" is actually a 52! lol its illegal! but who cares!

    i here the "80s" are pretty gutless and that the 48s are faster. is that true?
  8. dunno about the 48, haven't ridden one, but the 66cc out of the box are reasonable.
    1st I took the base gasket out, "cleaned up" the ports and machined the "lip" off the head, that made a difference.

    Then I changed the carb to a 16mm TK of a Yamaha scooter, better again.

    Then I ported it following this http://www.motoredbikes.com/showthread.php?t=5516&page=2 including a bit of work on the transfers, better still.

    Then I made a new manifold out of 25mm pipe with a boost bottle, opened up the exhaust at the flange and at the same time took a bit more off the head, I could beat my mates 2500 buck Bowell scoot up to 40 K/MH and taking off hard at the lights (peddling at same time) it would power wheely over bumps.
    Then I leaned it out to much and blew it up, lol
  9. those ports are small!

    and your carb is stil to small mine can run up to 18mm so im sure the 66cc should be able to handle a 20mm
  10. I run an 18mm mikuni on my 48cc.....
  11. s_beaudry

    s_beaudry Member


    You can take the easy way out for power and bolt a 6.5hp Briggs to a trailer on the back of the bike.

    Plenty of guts, trust me here!
  12. BigDaddyT

    BigDaddyT Member

    I been eyeballing a 6 hp tecumseh for a crazy build. I have a low hours engine beggin to be abused.
  13. wavygravy

    wavygravy Guest

    remember kiddies

    rember kiddies!these are motor assisted bicycles, not pocket bikes. keep it under 30 & rotate the pedals when ya see the man! wanna go faster keep it on the track please!
  14. zetti_the_man

    zetti_the_man Member

    my intake

    this is my manifold compaired to a stock chineese cast that most peeps have. it was lengthend and curved to fit a 20" frame.
    same dimensions to attatch to the same motor and carburator.

    Attached Files:

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  15. rotate the pedals when ya see the man!

    I do forget sometimes

  16. Bronzebird

    Bronzebird Member

    Does the 80cc have a "balanced" counter on crank

    from what I have on heard...the counter balance is not balanced. Any Ideas if this is true?
  17. zetti_the_man

    zetti_the_man Member

    hold your bike in the air and revv the engine.
    figure it out yerself mang.
    if yer bike shakes violently than no.

    mines got a nice shake to it :D
  18. Bronzebird

    Bronzebird Member

    My hands tingle after a 4 mile ride...Uhhh, I also have rubber pads at mounts.
    Maybe some gel pads on palms?? (joke)
  19. its not possible to balance a single cyl engine

    and the brigs and stratton has one flaw...no torque:oops:
    im getting to about 7 horse with my curent set up but i just bought a 48cc engine kit and i think that if i make a new crank for it and get rid of the silly gearboxes they have that i can make about 12thou rpm and have over 4hp easy i also by accident stumbled upon a way to make these bikes super quiet without loosing power! just wait till i get my site up i have some goodys for everyone!-TG
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