flipped jug on Chinese 2 stroke engine

Discussion in '2-Stroke Engines' started by butre, Jul 5, 2014.

  1. butre

    butre Well-Known Member

    it can be done, and it was even easy.

    I don't notice any performance changes that can't be attributed to shortening the exhaust header (power band shifted). I just did a little bit of port matching on the crankcase, modified the stock intake manifold and my noisy expansion pipe. total investment was under $4

    it runs just as good as before the modification and it looks different from all the other Chinese kits on beach cruisers you see.

    here's a link to a picture, I don't know how to make it smaller from my cell phone


  2. butre

    butre Well-Known Member

    one side effect is more ground clearance. I'm not smacking my pipe on the nearby speed bump anymore. I'm totally satisfied with this mod on that merit alone.
  3. butre

    butre Well-Known Member

    Temps (at least in the area around the engine) are noticeably higher with the hottest part of the engine out of direct airflow. I might finally buy that cr machine head Fabian has been championing.

    I've also pressed my leg against the exhaust twice now, so I'm buying fiberglass wrap tomorrow. I've got a major vacuum leak to sort out as well. I have one place I hope to find it on the intake, and one place I hope to god isn't it on the crankcase. if I'm lucky sorting out the vacuum leak might solve the temperature problems since I won't be idling at a million rpm
  4. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    #33 Bairdco has made many flipped motors going back years.

  5. butre

    butre Well-Known Member

    that's a huge pipe on there, makes the whole thing look pretty impressive.

    Now that I know it works, it's time to try a new carb. I'm thinking one of those PZ19 carbs from eBay, since I haven't seen one on a motorized bike yet. the thing should be good and quick when I'm done with it
  6. jaguar

    jaguar Well-Known Member

    you have my intake mod for low rpm power but you are using an expansion chamber without any header which makes it a high rpm pipe only. Put a header on it if you want to boost low rpm power.
  7. butre

    butre Well-Known Member

    I plan on doing that, the hardware store didn't have any appropriately sized pipe other than ridiculous 20 foot pieces so I just used the bits of the expansion pipe I had left until I can get something suitable.

    the intake mod was done more out of necessity than anything else, but I think I like it.
  8. jaguar

    jaguar Well-Known Member

    I think Home Depot may have some pipe that would be appropriate
  9. HeadSmess

    HeadSmess Well-Known Member

    scrapyards have the stuff just lying around and usually just say "take what you want" when dealing with boring old ferrous materials...
  10. keatonx

    keatonx Member

    Butre I'm assuming you aren't using your rear rim brakes like that lol
  11. butre

    butre Well-Known Member

    no, that's left over from when I was running a 26 inch rear wheel, I switched to a beefier 24 a while back and haven't removed that piece. It's going in the front as soon as I can find a piece of 6 mm threaded rod for dual front rim brakes.

    I haven't taken it off because I don't want to lose it. it's easier to leave it than to keep track of it
  12. HeadSmess

    HeadSmess Well-Known Member

    i tend to do that because its a far safer spot than that special place that things go when you want em nice and handy and instantly accessible... :jester:
    i can lose ANYTHING simply by turning around... its a gift :) or i have an infestation of gremlins, iunno!
  13. butre

    butre Well-Known Member

    I lost a 2 foot tall guitar cab in my house for over a year once. I don't know how I do it.
  14. Fabian

    Fabian Well-Known Member

    Did you flip the piston in sync with the flipped cylinder?
  15. KCvale

    KCvale Motorized Bicycle Vendor

    I resized your pic so it can be displayed.


    My mom used to always say if you don't have anything nice to say, don't say anything at all so I won't.
  16. butre

    butre Well-Known Member

    I did. I think I said so in the original post. if not, I meant to.
  17. butre

    butre Well-Known Member

    say it, I can take criticism. More importantly, I can't fix the problem or tell you why you're wrong without it.
  18. Bgnlb

    Bgnlb Member

    So you only spent 4 bucks,how much time did you invest in the project? Your carbs hanging out there taking on all the dirt and water from the front tire.there's no gain as far as I can tell..justsayin. It looks like you have some mechanical ability, I'm not hatin on you bro if you're having fun with it that's all that matters!
  19. butre

    butre Well-Known Member

    that was a concern, so I pulled the head off after about 40 miles to check for scoring and the cylinder isn't any worse than it already was. This top end already has about 1100 miles on it (and I'm pretty sure I was sucking up plenty of dirt as it was since I was using a velocity stack before) so it wasn't pretty to begin with.

    I've got a new carb coming in tomorrow that will mount in a way that any dirt that is getting in now won't be an issue anymore.

    I've also added some length to the header, now it's tuned for about 5500 rpm so I actually make some extra power with the expansion pipe now.

    the whole thing took maybe 2 hours including a trip to the city for the appropriate parts. I was done way before lunch.
  20. Bgnlb

    Bgnlb Member

    if its performance you want I'll let you in on a secret get someklotz
    racing fuel 123 should the trick.check out their website they have different Octanes