how did this project turn out? the ONLY stories I have heard about these OS 2 stroke motors are horror stories. if you want to fly gas, until OS figures their heli engines out better, stick with Zenoah. 9 times out of 10 the fuel fittings, and the fuel tank itself is just fine with gas/oil mix, its the fuel lines that need changing. you have a few options out there, but tygon is really my favorite. you can use the Zenoah line as well (black line). some guys use a combination of the two.....tygon from carb to tank for feed and return, and Zenoah for clunk line (it is a tad bit more flexible). if you have never run a 2 stroke heli before, be sure to do your research, or inquire from someone who has experience plumbing the tank and tuning a carb. totally different than nitro. the tank must be vented, it is not pressurized. carbs are extremely finicky too, 1/16 of a turn to far and your motor is smoked, not nearly as forgiving as a nitro. PM me if you have any questions, I love to talk motors and gassers
the OS motor is one that I don't know much about, but I do know a few guys I can get you in touch with that can help (in between re-building their own GT15HZ hahaha).