Originally Posted by SlowBalt
Just wanted to let everyone know I will only buy these kits in the future.
Both these engines have an improved high compression head with a proper squish band. And also come with an improved aluminum intake that solves the erratic idle that most kits have. both engine kits are identical except for the sprockets. The z comes with a 41 and the x comes with a 44. these kit also has the heavy duty 415 chain.
I've also switched the head and intake from my dead z kit that I roasted over reving it to 55 mph with a 30tooth to an older tired feeling engine and it ran like a beast.
Have you actually taken both of your motors apart? The reason I ask is because I bought both a X80 and Z80 motor kit, and I found several distinct differences.
A major difference was the engine blocks. The X80 had a wide 50mm front mount. The Z80 was regular size 40mm. The heads on mine are different.
The crank assemblies were identical, and were the bolt on flyweight type. The cylinders, and pistons were identical.
In this pic the X80 head in on the right, Z80 left. As you can see there's quite a bit of difference.
The sprockets in my kits were the same as you mentioned, and the X80 kit came with the bigger size gas tank.
I should also add that the crankshaft in my X80 motor was a lemon that was so out of true, and out of balance, that to motor went south in 500 miles.
The crank in the Z was better true, but still had way bad balance.
The question is, are these findings any different from any other China girl kits? IMO no.