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What's A Big Bore Kit?

27182 Views 5 Replies 4 Participants Last post by  SDscooters
So I was looking at things to make my bike faster and I heard about a "big bore kit". What is that? And are they hard to install? I heard about one on this video about this guy saying "I want to make my bike faster and was thinking about a big bore kit. I'm not good at the technical parts about the bike.". Does that mean it will be easy? And where can I find them? Thanks!
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A big bore kit is essentially a new cylinder and piston. most CAG motors have a 40mm piston and cylinder. A big bore kit upgrades the piston and cylinder's size to 44mm. In addition, the big bore kit has additional ports in the cyl., and sometimes even a windowed piston. There are 3, 4 and 5 ported cylinders, that come in either 1 or 2 pieces. What a big bore kit is meant to do is firstly upgrade the engines displacement (ever so slightly) and secondly increase the compression, thus more torque/power/throttle response.

installing the kit is relatively simple, making it work properly is another thing. Since all these parts are mostly all china made, their quality is questionable. Before installation, a lot of re-machining, sanding, deburring and polishing will be necessary if you want to feel real power gains. What this means is that you need to have some knowledge of working with metal, and also the tools to do so.

they can be found on ebay, or any of the online parts stores listed in the forums.
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And rather than spend 200+ on a bore kit I would save for a bigger motor I don't see it worth my time or money for 7cc's more
But doesn't a new motor cost WAY more then $200?
Ya basically about double that but if you saved 400 and got a bigger motor and has 3 times the power a big bore kit had and also once that power is not enough for you then you can get a big bore kit for that motor as well later on I personally don't see the point of spending that much for small gains of maybe 2hp as apposed to jumping up to 11-14 hp with a bigger motor
Guessing you have an X18 from your signature so I definitely agree with drgnprelude on this.

114cc bore kits are for those looking to stay within a racing class. They will make a 107cc/110cc perform like a 125cc for less money but will not be able to outrun a 140cc or larger. In the end the 140cc is a much better deal.

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