Another area that is prone to an air leak is the needle valve itself, having a
very small o-ring in it that after time hardens and will cause some erratic
engine runs or having to constantly adjust the high speed needle, a quick
fix is placing a piece of tight fitting fuel tubing over the barrel end of the
needle valve so that when is is screwed back down and reset it will act as
a secondary seal for that area. Having done this all on my 40, 51, 60, 90,
& 2300 ST's, I have taken at least one problem from the tuning problems
associated with Super Tiger engines, but like stated many times above once
you get them broken in properly, they are a very reliable & pleasureable
engine to own. I have also found that running 0%-5% in my 60 & 90 is what
they prefer and the 2300 runs beautifully on FAI (0%). But the nitro % is
ususally determined by the area of the country one lives in, higher altitudes
may require a little more nitro content than at sea level, also the moisture
content in ones air comes into play. But if you have determination you will
be happy with the end product, a reliable, smooth transitioning power house
that you'll really treasure.