Wiseco is one of the high performance engine parts manufacturer for dirt bike. I have stumble upon this great online shop
here with sells a lot of dirt bike parts.
This is good because many parts from the dirt bike Yamaha YZ125 can be fitted to Yamaha 125Z. One of the common part that is fitted to 125Z is the piston and connecting rod from the YZ125. Parts from YZ 125 are considered tough and long lasting as it is used in extreme condition that is in dirt bike racing.
Using the piston and conrod from the YZ125 are also said to increase the compression of the 125Z go higher than stock RPM, just make sure your CDI is not RPM-limited.
The parts here are not cheap though. It cost about USD150 (MYR510) just for the piston.
Anyway, from the reviews that I have read, many customers are satisfied with it. It increase the top end of the customers bike.
What’s your view about? Buy it and then you know it.
More info? Get to
http://www.motosport.com/dirtbike/product/WISECO-PROLITE-PISTON-KIT-2STROKE/?prodId=1227763&bMMY=YAMAHA;YZ125;1988