Big Bores
Back in March, we discussed briefly some of the things to look out for when it came to purchasing and receiving your big bore kit. Now it’s time to discuss the options on kits that each bike we specialize in. In this blog, I will explain the differences and why one kit won’t work like the other.
What does it work on?
Both the Honda Ruckus and the Yamaha Zuma have big bore kits available to them; however, the Ruckus only has a piston option where the Yamaha Zuma and the GY6 have entire cylinder kits. This is because, as discussed in earlier blogs, the Honda Ruckus is a water cooled engine where the Yamaha Zuma (both the 50cc and the 125cc) and the GY6 are air cooled. There are cylinder kits for the water cooled version of the Minarelli 49cc two-stroke; however, that version was not sold here in the US for Yamaha.
Only a Piston?!
So, with only a piston as your choice, how do you do a big bore kit on the Honda Ruckus? Well, you have to take the cylinder to your local machine shop and have them bore it out. You will also want to take the piston of your choice with you, as the machinist will need to measure the piston in his shop at the temperature he is operating in. If not, there is a strong possibility that the measurement was taken at your house or garage will be drastically different than his shop. Too big or too small, either way, is bad. It’s also a good idea to take the tools you used to measure to him along with the piston and cylinder as well for comparison.
The Zuma Big Bore Kit and the GY6 Big Bore Kit both don’t have to worry about this. Since they will come with a piston and cylinder packaged together, there should be no worry with clearances. Again, measure before you blindly install, though. It is a very real possibility that you could have received a bad match and destroys your piston and cylinder. There is no warranty on installed parts that you didn’t measure before you installed them.
Now, we have pointed out differences in previous posts but the same goes for the GY6 and the Yamaha Zuma 125. Both engines may be Over Head Cam, 125cc engines, but their design is very, very different. Things like cylinder size, head stud spacing, even how the timing chains are routed are all different. The heat-sink fins of the cylinders are also different. Each one has a specific way air flows through each type of bike. So, no, you cannot install a GY6 Big Bore Kit on your Yamaha Zuma 125 and vice versa.
