Any advice on this big bore (180cc! ha!) kit?

[photobiker]

1. Depends entirely on the quality of the parts (complete unknown) and the knowledge and care of whoever puts it together (probably you - but it's a single cylinder air cooled engine, pretty simple, just don't do anything stupid like mix up the piston rings or install them upside down or get the cam timing wrong).

2. It should help a little.

3. What's your level of experience with engines? Can you read and follow instructions in the shop manual? Do you know to recognize something going wrong and STOP rather than forging ahead and breaking something? As engines go, yours is pretty close to as simple as they get. Trickiest bit for people who haven't worked on engines before is compressing the piston rings - it's not hard but you have to be CAREFUL. And you have to not do stupid things. Piston installed backwards is another good thing to not do. Still, systematic approach, check everything as you go, check check check and check again, and it's not that hard.

4. Shouldn't matter.

5. See answer to question #1.

Hope this helps ...

Thank you, yes this helps. It also helps to let me know "holy crap there is a lot I gotta learn still" I figured installing it would be a pain, but "cam timing" sounds like "Rolex repair" to me as of this posting... I have almost zero experience. If something breaks down on a vehicle, I can fix it pretty easily, but as for having a foundation of mechanical skills...it's pretty much learn as I go.
As for the "depends on the part quality" before it blows up... is this something you could tell once one has the part in hand? Or is it more like...maybe the metal will fail, maybe not...

As mentioned in the ad, there's no fueling modification supplied with the kit. You can't just put it in and run as is.

That's the jetting fix, yes/no?

IIRC this is a carb engine. The carb will kinda-sorta respond to more airflow through it by drawing more fuel through the same jet. As a first guess and in the absence of any real-world experience, put in a main jet a couple sizes bigger and see what happens. Get it checked on a dyno with exhaust-gas analysis pronto, though. On that hard-working air-cooled engine, you do not want a lean condition under heavy load, but too rich is no good, either.

edit: On poking around, it appears that Kymco uses Keihin CVK carbs, which plenty of Honda and Kawasaki bikes also used before switching to fuel-injection. Haven't found what that specific bike uses but other similar models seem to use those. You can get Keihin carb parts anywhere. Maybe ask the vendor if he has any jetting suggestions. Jets are a few bucks each, here.

You say jets are a few bucks "here" as in a link you may have not linked or as in "here" like as in Canada?
As for carb.. yah it is a Keihin CVK 25mm

The owner might care if that piston comes apart and takes out the valves and damages the cylinder head....That wouldn't be the first time Ive seen cheap bore kits self destruct causing major engine damage

Yes. I would care. A lot. But also kinda sorta hoping it might be worth a calculated risk..

Being that Kymco is made in Tiawan why would the BB kit be any worse? Hell the CBR125 is made in Thailand? Just follow BrianP you will be fine. I have done a bunch of scooter BB that arent a whole lot different and most kits are asian (various places) and although not Rolls Royce they seem ok for the small bore stuff. My CT70 has had Chinese 110 engine in it for years now and runs like a champ. That said I dont know how much a 30cc bump will mean in way of performance.

Sounds promising...in your experience, what would you predict a 30cc increase would do? Maybe 1-2 horseys? It would be great to not slow down on hills lol.


Thanks for the advice so far guys. Hope everyone's weekend was good... one more month of winter almost over .