I have two different engines, in two different planes and both die when I get to the top of vertical and chopping the trot. for doing a hammer head turn. One is a Saito 82a in an Edge 540, the other OS 91 Surpass in a Cub. I had a 4*60 with a ST 60 and it did Hammer heads great. I put the 91 from the Cub in it and now it Quits. Tanks are set up with three lines. Double Clunk, on fill and Carb. supply. I even completly Changed one tank, lines ect. Made knowdifference. In every other aspect both engines run great.
Suggestions?
Thanks

Try the high speed needle more open two clicks and see what happens on the Four Star

How long (time) is your run up to the vertical?  If you take a long time, you will be plagued with the problem.  Make sure your pressure line is on the muffler and does not  have a split or hole in it.  Fuel has got to be lifted from  the bottom of the tank all the way to the carb.  That is some distance of achieve.</p>

Cheers,</p>

Chip</p>

You are running too lean. Check both high and low end needles.

<span style="font-family: Comic Sans MS"><span style="font-size: medium"><span style="color: #ff00ff"><span style="font-size: small">Thanks guys, will give it a try on Sunday.

Vertical run, can't be more than 3/4 seconds. (Guessing)

Rich</span></span></span></span></p>

I have a SSE with anSaito 82, and Ican take it off, point it straight up for 15 - 20 seconds before entering a flat spin. ALWAYS run your engines on the rich side.