I've noticed on Aliexpress and eBay you can get engine parts like valves, pistons, rings and more out of China for pretty much all the Japanese 4 cylinder 250s. The prices are crazy cheap and I'm guessing might soon become the only option for things like pistons and valves for some bikes. I've Googled and searched the site and haven't been able to find much if any first hand info on their quality and reliability. I'm considering some parts for one of my GSXR engines and would love to hear info from anyone who has experience using parts in any of the l4's and any feedback they can give. Compatibility problems? How long have they been lasting, any major failures, type of use etc?
I can only speak to what I have read on another (cbr250rr specific) forum. Pistons were significantly different than OEM and required work to have proper clearances. I've heard nightmares of horrible gaskets being sold, and my own experience with a chinese radiator tells me that there is plenty of crap out there. On the flip side you can find quality parts made in China, but how it's done without paying for the experience is beyond me.
Although China has the capacity to produce quality items, they don't bother doing it unless you place a substantial order for yourself. The vast majority of bike parts produced there are for general public. And to maximize sales, they make it cheap and affordable. Yes, there are good quality parts coming from there, but it's not easy to find, and quite expensive to order a batch. I wouldn't risk using those cheap parts inside the engine, where I couldn't inspect its performance and risk massive (and expensive) damage. Have you checked Japan? They have many eBay like sites there, where you can buy aftermarket Japanese parts. They do have a reputation of keeping a decent quality on their products.
