Hey guys! Sorry for bringing back such an old post, but I have further questions, about the banana pipe. I actually get more top end from it.
Now I read somewhere a few days ago, that the ones with the stinger comming out at an angle, are actually GOOD, and off of a pocket bike, but not for these engines. I've read, that the power band increase is somewhere around 14k RPM, wich my 66cc 2 stroke will probably never reach, if it would, well I don't want it to. I'm not sure how to calculate this, I'm probably saying something VERY stupid, but here's my try:
The end of the stinger (visible) that comes out, is 2,5cm. I'll assume it goes in about 0,5cm too. That would make it 3cm long. Now if the increase is at about 14k RPM, and the stinger is ~3cm long, that would mean, that 1cm of stinger would be good for 42k RPM (???) I belive these engines shouldn't really go over 9k RPM. I want a mid-high RPM torque boost. If I did everything correctly (according to my logic) I should have a 6cm long stinger, for a 7k RPM boost. If its squared, then I'd probably need just a centimeter and half to add on. I was also thinking about drilling it out a millimeter, so the inside of the stinger is a bit wider.