Which big bore kit? ---- Z-125

Get asked this about 5 times a week, posted about it in forums numerous times but i dont think anybody reads it!.
I dont quote top speeds as its impossible to claim, but your stock bike pulls at least 55mph, everything below will nudge it past 60mph at least......... want more, you need gearing and thats another subject for another time.

(its important to note that you will need AT LEAST a aftermarket clutch of some kind in order to do any of this!)

There are almost infinite possibilitys of displacement on our engines, to save you lot time i shortened the choice down to a few sets........ well theres still quite a selection:

• 155cc
• 164cc
• 192cc
• 202cc
• 215cc
• and more if you sweet talk me via email!

Not good with tools and trying to install this yourself, skip the paragraphs below and just choose 155cc, that bolts right in place of your old cylinder/piston and can use the original pipe and throttlebody without a hitch, you can upgrade to a 32mm throttlebody later on for more power and speed if you wish.
With the right CVT settings you have around 11bhp+ with this setup.

Pretty good with tools, have good or reasonable knowledge on how a 4 stroke engine works?.
Well 164cc is the one for you and is my personal choice for our daily rider!.
Same big bore kit as the 155cc kit but with a 3mm stroker crank, this means spilting the cases (complete bottom end rebuild)
Makes more torque than the 155cc, revs alot higher, feels smoother and obviously makes more bhp.
CVT settings are very crucial for this setup, get the roller weights wrong and it will be the same as a 155cc.
To get the best from this setup you need a big exhaust (yoshimura make a good one) and a 32mm throttlebody.
Peak power of around 14-15bhp.

Sending the bike to a tuners or have done bike or car tuning before?.
Well 192cc and above is for you, reliability stays the same regardless of engine size thanks to the strong piston/cylinder and crank combo, just choose one to suit your budget.
You will need to machine/bore the crankcase, install a new aftermarket crank and head.
These engines go balistic when around 200cc, they rev to the moon (shy of 10,000rpm) and pull very hard, if your not careful from a launch you can flip the bike easily*
* I have heard of 2 experienced bike riders doing this in the past few months, im serious, be careful!.
Hard to quote figures as i have only dynoed a 223cc, but 20bhp is about right.

Hope that helps.