rc pilot
any progress? after opening my exhaust port up to 137 degrees with my dremel , and dropping the bottom of the exhaust port just below the piston top, smothing, and polishing the port I am happy to report 250-300 rpm gain!
on the stock carb.thats not to bad for a little elbow grease Im now at 7650 rpm's(I lost about 200 due to a replacement carb not as good as original) I may do a little more and see what happens
some new advice,LISTEN TO AERO NUT, he may just be correct about the exhaust port on your engine. I took off 1\2 mm, maybee and picked up at least 200 rpm.
140degrees duration, thats the ticket. at least measure your duration so you know what it is.aero nut tells how back a few replys its easyand its cheap!

aero nut thanks and now I understand about the timing thing on the exhaust any idea how far you can take this? 150degrees maybe ,If I remember correctly 160 degrees is tuned pipe time right?