The golden rule of 2 strokes is JETTING IS PERFORMANCE.
If you are afraid to change your jets, your bike will never acheive its potential. That is the wrong plug. You could do damage to your piston or cylinder. Put in some leaner jets and the right plug. Yes, you will sacrifice some riding time. But if you do this right, you will be amazed at the power of your bike, and you will glow with the knowledge that you did it yourself. And yes it won't foul plugs.
If you are apprehensive, start with just reducing the main jet one size. You don't even have to take the carb off the bike. Just lossen the clamps, rotate the carb so you can loosen the nut on the bottom. With that nut off, you can see the main jet. Remove it with a wrench or socket (not pliers). It should have a number on it. Go to your nearest dealer and show it to them and ask for one size smaller. Put it in and give it a try. If you can't notice the difference, I'll buy that jet back from you.
Part 2: Do this instead of the above. Or after you've done the above. Do NOT do it at the same time. Never change more than one thing at a time because you won't know what affect each thing had. This is free. Unscrew the top off of your carb. The top and the slide will all come out. There is a long needle hanging out the bottom of the slide. Disassemble the slide and cable to remove the needle. The needle has a clip near the top. The clip is in one of 5 slots. To make it leaner, move the clip to a higher position on the needle. Reassemble. When you return the slide into the carb, there is a pin in the side of the carb that has to line up with a slot in the slide. It will be clear when you do it. Occasionally, the needle does not fall right into the hole in the bottom of the carb. A little gentle movement and wiggling usually let's it fall right in. Do not force it. After it is back together, be sure that your throttle works smoothly before you give it a kick. On most of the bikes I've worked on, the slide just falls in to place during reassembly.
Read a little more about jetting and you may be surprised how easy it is and how much you can gain. Every rider should be able to change a main jet and adjust the needle position.