I've found out the hard way that Sullivan tanks are problematic almost all the time. The same for the blue silicon fuel lines. I've had more leaks and pin holes in new line than I care to remember. There is a thread around here about using the pink Prather medium fuel tubing. I've used that and never had a leak. It is tough and about the same price. It's worth changing when you consider that it will last a long time. I changed all of my Sullivan tanks to the Dubro tanks with the notched front. Those seem to be much better and better made. The Sullivan stoppers will leak and turn brittle. The hardware fit on the Dubro parts are better.

I'm having a difficult time with my .72 and I think it is an air leak somewhere. I just put the carb back together today with new O rings and a new velocity stack. It began to spit fuel. The engine seems to run fine with excellent power on the first fllight. The second flight is usually good too. But, the third flight is where problems begin. It seems to sag in the air and it sounds lean. Richening it on the third flight seems to make it run okay. The fourth flight is where it just won't run right. I can go either 1/4 turn lean or 1/4 turn rich and the engine sags, RPMs are all over the place without reason, and won't tune at all. Nothing works at this point and it's time to pack up for the day. I put RTV around the manifold at the cylinder and that seemed to cure everything for about 5-6 trips to the field. Then, the problem came back with the fuel spitting added in to make things more interesting. I'm flying it tomorrow, so I'll know if the carb O ring did the job. The low speed needle valve seems easier to turn now. I also stretched the spring out some as it began to die every time I adjusted the LS NV about the same time my problems began.

I almost forgot. Blowing on the fuel lines to check them for leaks sometimes won't show them. I found that out too.