[grabs an early morning coffee - takes great pleasure from HeadSmess's post]
I need a good dose of humor at this time in the morning
and yes, (prior to gaining competence at replacing the 2-stroke crankshaft in Chinese bicycle engines) i used to just bolt in a replacement engine into the bike without any of the horrendous issues that other people have described.
The engines i have purchased are imported into Australia by Powercycle and from what i understand they are sourced from the Nantong Jali factory, which seems to do a fairly reasonable job with the assembly process.
I have never had any engines catastrophically fail (then again i don't rev the rings out of an engine) but over time they just slowly wear out, like any mechanical device.
The engines that have failed prematurely used the caged connecting rod big end bearing design, but having said that, i am still using an original (replacement crankshaft) caged connecting rod big end bearing design (purchased about 5 years ago) in my current engine, and with the Jaguar CDI it's still going strong, which confirms my initial thoughts that the original stock standard CDI is responsible for the majority of connecting rod bearing failures.
Having said that, my engine supplier said that the crowded connecting rod big end bearing design has drastically reduced the amount of engines being returned under warranty, though the engines that i examined showed obvious signs of abuse or simply a failure to add 2-stroke oil to the fuel.
For the time that i have been using these 2-stroke engines, i am more than impressed with the reliability that they can be made to give, considering the low purchase price, not only of the kits, but also of replacement engines. $100 for an engine that will cover 6,000 miles on a bottom end and 2,500 miles on a cylinder is a stonkingly good deal, and then when the heart of the engine dies, it can be replaced for $30.
Not a bad deal in any language.