skyteam ace 125 removing cat

Before I start I must say that this is not a fun job. If you can buy a replacement header for a good price - do it now!

As shipping to Australia is too expensive, here's how to do it.

Tools required. You will also need an angle grinder, metal cutting disc, power drill with a very long drill bit and a bench vice.

Remove muffler bolt. 14mm wrench.

Remove the header bolts. 10mm.

Cut here or further up to be closer to the cat - not that it will help you remove it. If you want to use the existing exhaust and weld it later I would recommend doing it the slow way with a hacksaw to get a perfect cut. Metal looks thick enough to be mig welded with gasless or even arc welded with an inverter only.

Here's what's to be removed. It will take a great deal of time as it is densely packed metal that is glued in. Drill towards the sides to remove the glue. Drill in the middle to make it less dense.

You have removed the terrible, terrible cat and deserve a beer. Install your new exhaust or weld the existing exhaust back. If you plan to slip on a new exhaust ensure you grind down all the welds on the outer part of the pipe as a slip on must have a very flat surface.

You will most likely need to adjust the idle and mix.

Adjust the idle as pictured and the fuel mix screw which is screw with a grip underneath the carb outlet.

This will take some time and some care. Only make small adjustments (1 hour out of 12). Tighten to increase, loosen to decrease. Wait a minute after each adjustment. If you are using the stock muffler and cat it may no longer like slow idles.

It is best to start with the idle screw at the bottom of the carb all the way in (lean). And to keep your idle at a moderate pace. Slowly increase the fuel mix screw as you slowly decrease the idle until it happily idles just above stalling. This is the minimum for it to run, but at this point I prefer to increase the fuel mix so it runs richer on idle to stay warm and prevent stalling at lights. I also prefer to increase the idle for the same reason.

Enjoy the new performance.