My OS 91SZ-H hyper seems weak inverted

[angelob]

I just swapped my YS91 for this new OS 91 SZ-H hyper and I seem to be having an issue - the motor seems to load up inverted and has a hard time climbing. I also notice it in flips - when upside down, I lose headspeed. I have 2 gallons through the motor at this point.

Here is my setup:

Fury extreme 8.18 gear - 10.5,0,10.5 pitch curve
Blades - Radix 710
Muffler - Hatori #998
GV-1 - I have varied head speeds from 1750 to 1900
Needles - High .75, mid .5
Using cool power 30% and .016 shims on head


Now I never, ever noticed anything like this with my YS, even just after a couple of tanks. It seems like this engine is down on power - my YS seemed more powerful.

Maybe I'm missing something her, but I'm not sure what.

Thanks for any input,
Angelo

[3DWONDER]

i have heard that the 8.36 is the best ratio for that engine i have it in my stratus and it is insane i dont know if this will help but there ya go
todd

[angelob]

Well, I figured out my problem - actually it was several things. First, my pitch curves were off - I had a mishap and was sloppy rebuilding and mixed my links up from what they were originally. My pitch curve wound up being +14,+3,-5. So I fixed that. Second, I'm running the hatori 998 which is for both YS and OS. Looking at the mounting flange, it appears that the YS holes allowed leaking from the exhaust port. So I filled those with JBweld and my leak went away. Once I did this, the engine was pretty close - just needed to lean out the mid a little. I'm down to about a 1/4 turn out on the mid.

I love this engine - it seems to make tons of power and easy starting.

[3DWONDER]

glad to see that and good luck with it
:lol: :lol: :lol: :lol: