Recommend an 80cc motor

Discussion in 'Motorized Bicycle General Discussion' started by SuedePflow, May 15, 2014.

  1. SuedePflow

    SuedePflow New Member

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    Hello all,

    I'm looking to replace the motor on my bike for this summer. Unfortunately, my bike had a little encounter with the lawn mower last fall and it now has a busted case. Rather than replace the case, I'd like to use this as my excuse to install a motor with a little more power.

    So, I'm after an 80cc 2-stroke engine. I'd like to have something around 4hp if possible. And it's got to be of the same mounting configuration as the regular china girl kit motors. Budget is mostly open, but I'd like to keep it under $200 if possible.

    Give me your recommendations and thanks in advance!


    [​IMG]
     
  2. Goat Herder

    Goat Herder Gutter Rider

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    There is no such thing as a 80cc motor in a china Happy Time kit. 80cc is a bad advertisement by any vender really as none of these engines are or ever were.
     
    #2 Goat Herder, May 15, 2014
    Last edited: May 15, 2014
  3. SuedePflow

    SuedePflow New Member

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    80/66... Whichever you'd prefer.

    I've personally always included head chamber volume when calculating engine displacement and don't see why anyone wouldn't, but that's for another discussion.

    Do you have a recommendation of a good "bigger than 49cc" engine?
     
  4. Theon

    Theon New Member

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    If you put 4 HP on that you wont be able to keep the front wheel on the ground!
    Would be fun!
    Your going to pay more than $200 for anything close to 4 HP.
    Depends on how much you do your self.
    If your old motor is a standard 38 mm stroke slant head motor, my advice would be to start with a 40mm stroke GEN4/GEN5 motor from Dax or MBR, Give it a little more compression and a porting and you will likely not be disappointed.
    If still looking for more, then try a decent expansion chamber.
     
  5. SuedePflow

    SuedePflow New Member

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    I found Dax's website, but do you have a link to MBR?
     
  6. Theon

    Theon New Member

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    Not sure,
    Try Private messaging him.
    MotorBicycleRacing.
     
  7. Goat Herder

    Goat Herder Gutter Rider

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  8. SuedePflow

    SuedePflow New Member

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    Bringing this back.

    Forget the 4hp goal. Who sells quality 66cc engines? Just something better than the regular Chinese stuff and less than $200. I read something about Japan engines being of the best quality, but I have no clue where one can be purchased.
     
  9. Davezilla

    Davezilla New Member

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    Check Dax's website.. His engines are of good quality and you can get one for well under $200. I'm using a Dax bottom end on my latest build and I gotta say it's the smoothest running China Girl I've built so far. The Dax F80 engine sells for $129 and it's very smooth and reliable, the RT carb he sells on the same page is a good match for the engine and will give you decent power when combined with a decent pipe... and you're still under $200
     
  10. etard

    etard New Member

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    Honda CR80. Basicly, the same motor for all years of production, way more than 4 hp and gears to boot!
     
  11. maniac57

    maniac57 Old, Fat, and still faster than you

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    I really like my GenV. The engine was less than dax's and is identical AND assembled.
    MBR is a little harder to get ahold of but well worth the trouble for anyone wanting the 40mm better balanced chinagirl with upgraded hardware at a good price.
    For stock engines, I use rose326 on fleabay. 25+ kits and counting.
     
  12. mapbike

    mapbike Active Member

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    Go to thatsdax.com click parts link and the click on page 3 scroll down until you see the Gen IV lower if you want to just build the engine up yourself, you can order a full upper jug kit with all you need on ebay fdom boygoesfast and have a nice solid running engine for about $100

    You can also just make it easier by contacting Neil motorbicycleracing through private message here on the forum and he can fix you up with the same engine and get it all at one time from him for probably less than $120

    Neil calls his Gen V engines and they ars actual 40mm stroke engines with better than average crankshafts in them, I have three of these type engines with two of them currently built up and them are very good runners and performance with a few mods is outstanding.

    Map
     
  13. Davezilla

    Davezilla New Member

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    I've got stuff from Rose326 before and they sell good stuff too... Hadn't got a complete engine but lots of parts and they were all good.
     
  14. Davezilla

    Davezilla New Member

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    That's what I did on my last build... I used a Dax Gen IV bottom end with my old jug and piston since it was already ported and not yet broken in. You could use the Dax bottom end with the BoygoesFast jug and piston and come out ahead since BoyGoesFast sells the jug and piston kit for under $25 you would come out ahead, You'd need to buy a wrist pin and clips from one of the sellers tho but you can't beat $25 or less for a jug, piston, and rings, with an intake manifold bolted on.
    For the head, the Puch heads bolt right on and cost about $40 and they're far better than stock when it comes to cooling and chamber design, and trhe Fred heads are around $65 or so but also offer superior cooling with excellent compression and a good chamber design as well. I'm running the Fred head on mine and I really like how well it keeps the top end cool, it's the better looking head since it's built for this engine, but the Puch heads are right at home and look pretty good on these as well, performancewise, they're pretty much identical so it's a matter of how you want yours to look. The stock heads can be modified to offer good compression but they can't even come close to the cooling ability of the Puch or Fred heads.
    Both the Dax Gen IV and Neil's Gen V engines have the improved 40mm cranks to give you 70cc ... really about 69.5 or so but close enough. They both are very well balanced so they will run smoother than most others as well and come with better bearings already installed.
     
  15. mapbike

    mapbike Active Member

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  16. SuedePflow

    SuedePflow New Member

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    What's Neil's username here? Or e-mail address?
     
  17. mapbike

    mapbike Active Member

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    Neil's username is motorbicycleracing

    Best wishes on your build

    Map
     
  18. SuedePflow

    SuedePflow New Member

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    Well, 3 days later and no reply from Neil...

    I guess I'll contact Dax next.
     
  19. mapbike

    mapbike Active Member

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    My recommendation would be to order a 66cc Lower from Dax and the order the entire upper from boygoesfast, clean up the intake and exhaust port just to remove any burs from casting which all of the jugs have that I have ever bought, and build it up from those parts and you should have a really good running little engine in the just over $100 range.

    Bottom of this page and you'll see the Lower listing
    http://thatsdax.com/ENGINE_KIT_PARTS_PAGE_3.html

    And here is the link to get to the upper engine kit from boygoesfast
    http://www.ebay.com/itm/191036700418

    This is the route I would go unless Dax happens to have and entire set up that he just hasn't listed on his site.

    Map
     
  20. KCvale

    KCvale Active Member

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    If you want to assemble the whole motor yourself you can get a 'Skyhawk' from gasbike.net for $99 delivered.
    There 'summer sale'

    http://www.gasbike.net/66cc-racing-...rt_affiliate_id=194">14june</a>

    I bought a couple yesterday simply because I could and I'll go from there as I can always use the spare parts but in short cheaper overall for me to just buy the already built engine and kit for $187 delivered.
     

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