KymcoForum.com
Scooters - 50cc => Agility 50 => Topic started by: The moped learner on March 15, 2014, 04:41:45 AM
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I was wanting to get a 80cc bore kit for my moped this is the link
http://m.ebay.com/itm/201036542552?nav=SEARCH (http://m.ebay.com/itm/201036542552?nav=SEARCH)
I was hoping it would help with cold starting is there anyone that put a bore kit on there kymco 50? Is there anything i should look out for, beware of anything? Thanks
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Big bore kits unbalance the rotational dynamics (http://49ccscoot.proboards.com/thread/7767/39mm-47mm-piston-compairson-video) and enhance bearing failure.
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Not worth it.for cold starting all you need is bigger jet and better air to gas mix
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These kits (I got mine from ScrappyDog) are really awesome. The starting & acceleration is really impressive, although the top speed doesn't change much. I also added a performance CDI to increase max RPM, and a set of hi-speed gears to increase top speed. The Kymco 50cc 4T SD10E seems to be a standard qmb139 engine, and every qmb139 part I've used fits exactly. I now cruise easily at 9,000rpm at 45mph (70km/hr). The only part needing some extra research are the reduction gears (one of the gear clusters is a Kymco piece, not a standard qmb139 piece. But it's easy to sort out). Another tip: the 80cc kit is a 60% increase in engine size, and the little battery struggled to twist the qmb139 starter. I upgraded to a 7-series battery and it now starts like a pistol shot! Other parts used: #90 carb jet; straight-thru sport muffler. Removed intake restrictor grommet, but kept stock air filter & box. Switched to 7gm variator weights, Honda Dio Keli variator with stock clutch. It's really loud now - and really quick!