cdi upgrades? where to get them?

What do you mean by, "performs better" ? The stock, kit supplied CDI will deliver everything that your engine will need. Even many race bikes rely on the kit CDI. Those aftermarket, overpriced placebos you see on ebay and other places are just that, placebos that claim they will increase power. It just isn't true except in the minds of those who buy them.

As long as your kit ignition produces a spark that's all that 's needed to produce combustion.

The myth that the kit spark plug wire is inferior has been the source of a lot of discussion. In fact the kit wire is better than anything you'll get at the local auto parts store because it has a metallic core, or conductor where the parts store wires will almost without exception be resistance wire. It will have a carbon impregnated thread at its core, not metal wire which results in more resistance (less spark). The biggest problem with the kit plug wire is the length. They're usually too short to allow mounting the CDI anywhere but on the downtube, close to the engine. The other issue is most kit suppliers have turned to gluing the plug wire into the CDI which makes replacing the wire a little difficult without some digging.

What is a fact is that the kit supplied spark plug boot is nothing but junk and should be tossed in the trash when you open the box. It should be replaced with a good automotive quality plug boot and a spark plug with the top cap still installed.

Tom

Thanks, but no thanks, Huffy. I've built more but I currently have four running bikes that start everytime, idle perfectly, have good low, mid and high range power and any one of them will pull me over 40mph. They all have stock, kit supplied CDIs and in nearly 6 years of building and riding motorized bicycles I've not had one CDI failure. Not one!

Unless and until someone builds a reliable dynometer to test a Chinese 2 stroke engine and can show me undeniable proof that a change in ignition source will provide a measurable horsepower increase I'll stand by my earlier comment. That being that if a spark occures in the combustion chamber, given the correct fuel to air ratio, combustion will occur and the engine will run. How that spark is generated has absolutely no bearing on the intensity of the combustion or the power that is produced.

The illusion of more power can be achieved by many things. Billet intake manifolds, So-called "high performance" air cleaners, open or unrestricted exhaust, etc. can provide a feeling, or at least a chimera of a measurable power increase. Illusions, for the most part, are more expensive than their stock counterparts but give the buyer a sense of achievment.

There are things you can do to increase the performance of these little Chinese wonders but making a bigger/hotter spark isn't one of them. I'll save my money and put it toward tires or at the least, gasoline and oil. But thanks for the offer.

Tom