My single-cylinder bike (e.g. Yamaha XT600) starts badly and won't idle; I suspect the CDI. Which Ignitech unit do you recommend?

If you only want reliable starting and idle (not extra performance), the non-programmable DCCDI is enough; the programmable DCCDIP lets you adjust the curve later. The unit is supplied with the same connector as the original, pre-programmed for your bike. You only need to connect one extra wire to a +12 V key-switched supply.