OS 91 FX in Shoestring Racer
Serge,
Yes, it happened quicker when I was at full throttle for longer periods of time but I was only at half throttle when it actually died. When I test ran a few tanks through it at home I found that it would not four cycle no matter how much I turned the needle out. That told me that there wasn't enough back pressure in the muffler for the tank so I plugged one of the pipes on the muffler. It's a Bisson Pitt's 70 degree. Now I'm wondering if I have plugged it too much. After I wrote my last message I went out and searched on FX91 and found a bunch of solutions many have tried. Solutions from enlarging the fuel line supply to shimming the head. Problem is I have little experience with this and am not too sure where to start. What muffler are you running? I think I'm gonna start with only partially plugging the one exhaust port to see what happens. Then I'll try removing the cowl. Those seem like the easiest to try first. As far as the clunk goes, do you mean to make sure its free or something else. I've made 4 successful flights but those were running very rich and at half throttle. If you have any other ideas, please let me know.
Jeff