I'm a professional technician and build engines for a living. Bikerberry is sketchy at best, they sell parts that are incorrect for the 66cc and "larger" engines, the 2 valve reed valve is one of them. They are very, very overpriced, a great example are the NGK spark plugs they sell for 9$, same plug at an autoparts store for 2.49$. My friend ordered a few engines from them, one of the 66cc engines, was indeed a 49cc, we made absolutely sure of this. Called bikeberry about it, and they simply said we are wrong and the conversation went no further, bad business.
Another thing to note, and this is not bikeberrys fault. There are NO 80CC grubee engines, clones or not. they are almost all 66cc, we have literally taken measurements from over 50 of these engines (from different supplies) and they all range between 49cc to 66cc. The "80cc" is nothing more than a sales pitch from someone who did the math wrong.
Another thing to note, again not bikeberrys fault, the flying horse engines are overpriced, mainly because they are mostly just stock engines. We've purchased 3 of them, all 3 are no different than the stock grubee engine, some of them come with a cnc cylinder head, smaller chamber for more compression. bikeberry offers this engine, with a"stage 1 CDI", which is just a stock CDI with a red shielded cable and fake NGK boot. If you don't believe me that its fake, call NGK as i did.
It might sound like im slamming bikeberry, but i'm not. I'm just being honest, and calling them out on what i see as dishonestly. Hopefully they improve their bussiness tactics and stop, for lack of a better term, ripping people off. Have a nice day