Plastic welding 

A simple weld for a split side panel
Here you can see the panel I needed to be done, it's from my own Kawasaki GPZ RX1000 (ZX10a)
 I did try to use plastic padding for this job, but it split a second time before we even primed it. That was before I learnt about plastic welding.

1. Sand the panel where it's split, removing all paint, and any scratches which you can. 

2. Clean the area where the weld is to made both side.

3. Shave small pieces if plastic from an old plastic fairing, preferably of the type of plastic as a different type might not take. Then place the shaving on top of the crack. 
 try to make sure the two side of the crack are as close to where they should be.

4. Taking a soldering Iron, melt the shaving into the crack.

5. Turn the panel around so you can begin the back of the weld, Make sure it's been cleaned, then take more shavings or a good strip of plastic, and meld them over the split. Make it wider than the split to give it strength

6. Sand down the weld on the outside (the side people will see). If any pieces fall out as sanding or if you see hollow parts, clean the area again and melt a bit more into the hollow. Sand it down until you are happy with the result.