I've spent a lot of $$ on CDI modules for my Kymco Sento 50 with 80cc BBK, cam, gears, tach, etc. Some were a real waste of money! For use in a Kymco, CDIs must be the larger DC models; The smaller AC CDIs burn out about 2 seconds after starting.
CDI, 'A' in the photo with the yellow case is my favorite. I don't know who makes it, and it comes with no how-to instructions, but it's really excellent, unrestricted to 10,000+rpm, easy starting with a nice idle, and only for about $15. It's a direct plug-and-play. The timing is adjustable with the little screw shown. They're for sale on eBay from ATV shops for about $12. It's totally unique, so I'm pretty sure they're all the same model, no matter where you buy. Some are listed for $55, but others listed for less than $15. Search on eBay for "CDI DC", they don't appear if you search for "Kymco CDI".
CDI 'B' from ScrappyDog is unlimited rpm with fixed advanced timing. Good price, but very hard to start; quite loud and snappy when running. Almost impossible to start in winter when motor is cold. Maybe OK for scooter racing, but difficult to live with as a daily driver.
CDI 'C' is from Scooter Assassins, very expensive, about $35 plus overseas shipping. Starts OK, unlimited rpm, but TERRIBLE mid-range performance. Not worth the money.
CDI 'D' is the stock Kymco CDI, normally limited to 7,000rpm. Increases to 8,000rpm limit when the case is cut as shown. The rpm limit is imposed with a wire that runs along the edge of the case. Cutting the wire raises the rpm limit, but not by much. Cheapest solution to Kymco rpm limits.
Although the unlimited CDIs can run up to 10,000rpm, this will severely shorten the life of your Kymco! I try to keep my rpms down to under 9,000rpm (install a tach if you can, cheap Chinese ones are less than $20 and are reliable).
