I have the OS LA .15 and its a super little engine for less then 60 bucks with tax.
Like they said... drill out the baffle at least twice as large of hole.
I cut the needle valve assembly off the back plate and just let if be supported
by the fuel tubing and it works fine.
15% cool power fuel.

I took mine apart and lapped the piston in and then ran one tank of fuel on the ground.
Ran it rich and then would peak the needle till it stopped two cycling and then right away
turned it back rich. Do this through the first tank. Run just slightly rich for first 3-4 flights
and after that it was a screamer. Cuts down the break in time to an absolute mininum.

Wayne G.