Serious 49cc mods

Discussion in 'Performance Mods' started by two smoke, Jan 30, 2018.

  1. two smoke

    two smoke New Member

    Jan 14, 2018
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    I recently acquired a 49cc china engine kit and figured it would be something good to keep my mind occupied during the winter. So I got it put together on an old panasonic bike from the 70s that doesn't weigh much and want to know what mods are worth doing to get it moving a bit quicker. Internal mods & bolt ons. Im new to this forum but theres talk about a "speed carburetor" the carb on it says speed and also has chinese writing on the choke, is this the 'better one' or do they all say that.

  2. Philandra Chambliss

    Philandra Chambliss Member

    Sep 2, 2017
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    Porting pretty much, there are no "physically tested mods or parts." For these engines.

    Specially for the 49cc's 66/80cc use most of the bolt on mods and have 8mm bolts.

    49s use 6mm your best bet is expansion chamber, from a medium sized dirt bike, porting the intake and exhaust ports on both engine side as well for the exhaust.

    As well for matching your gaskets.

    Hell one could cut their own gaskets to sht for base gaskets as well for the intake but not the exhaust.

    At the least,

    I can't tell you to swap around parts, but a 49cc is limited.

    It's about how much time, education, and knowledge you possess how bad you want it to ride.
  3. Street Ryderz

    Street Ryderz Well-Known Member

    Oct 14, 2016
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    The 48cc engine is a great little engine and can be made to out run the bigger 66's with their bolt on's.The smaller bore means smaller piston mass(less reciprocating weight) that will rev higher with less chance of damage,if you static balence the crank along with some port volume changes a good pipe and tunned well it will perform great.
  4. HeadSmess

    HeadSmess Well-Known Member

    May 17, 2010
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    i always found that it was best to leave the 48's as they are. they dont really need any work. maybe lifting the intake port a bit (piston cut) but not too much, pop the cylinder off and remove any casting flash in the ports, and leave it at that.
    other than strapping on a good tuned pipe.
    the tuned pipe makes all the difference.

    doing much more work than that always gave diminishing returns, as the engine tends to self destruct. nothing worse than spending two days porting a cylinder to perfection, getting some insane power level /redline, only to have something minor like a ring locating pin destroy the entire cylinder after twenty minutes or so. never had any major parts fail, it was always just these tiny, inconsequential parts you dont think about that end up causing issues...

    its alright if they die 100 metres from home... not so good when they decide to do it about 50km from home.