Hi, i have never attempted plastic repair before and have a couple of questions, I have a belly pan fairing from a 2004 Yamaha R1 to repair and a front fender of a VFR800 2002 to repair. Both have cracks in the plastic and I am not sure if i am going to do this right so wanted to ask a few questions.

VFR, looks a simple crack form edge to about 4 inches into plastic which is ABS. Do i drill a hole to stop spread? the carve a "V" channel with dremel and use a plastic weld to fill said groove? Do i do this on both sides? Obviously sand after completing and then prime before paint.

R1, this plastic is PPE and feels more like rubber than plastic, i have 2 splits in this plastic, one on an sharp curved corner and the other just underneath a hole for fixing fairing to frame, neither have gone to an edge, they are splits and i want to seal them before painting. How can i repair this type of damage. I thought simply heating the underside until it softens and then bracing them together until harden and rebound the split.

I have a plastic welder, but no idea how to use the setting dial on the top to adjust to correct temperature for appropriate plastic.

Any guidance on plastic welding would a huge help, i have a potential niche market currently and need to develop this skill to take advantage of it.

Thanks

Okay, first, go see somebody "do" plastic welding. If you go on YouTube you should see many videos of guys doing plastic welding. Second, a valuable source for information on plastic welding is over at.... www.urethanesupply.com Look on the left and you will see a "How to" section.
On the VFR you are mostly correct there. Drill hole stops and just V from one side would be fine. On the PPE you might need some filler piece stock or rod. I've never had a lot of luck in just melting the stuff back together.
As for using your new tool..... it's a lot about experimentation. Basically you've got to get the plastic just hot enough to flow (but not smoke or worse burn, don't laugh I've seen it happen) and stay "open" long enough to manipulate the "pool." Seems like every tool is quite different ranging from something no more than a soldering iron to the ones that use heat/air combo for more control.
Compared to the skill levels that are required in metal welding I think plastic welding is fun and easy to figure out.... just get a bunch of scrap plastics and start welding, write down your heat ranges for various plastics and keep some notes on what you did. Before you know it, you'll be doing good repairs rapidly and consistently.

Thanks DarrelK, strangely whilst you were posting i managed to score some plastics from biker mates who were more than happy to help when they realised i was getting into repair work.

Experimentation here we come. Should be fun.

If you get a chance take some pictures of your work and post them here. The learning curve goes pretty fast with plastic welding so you'll have some good work to show it for it soon I'm sure.