.. FARM work and bad weather have pervented me from doing the inportent things in life. ..I did geat time at knight to put 91 from cap back on the test stand....13x8 ms prop 15 omega fuel os#8 glow stock muffler with baffful..this is a test stand mounted on bench fuel tank center line ( 16%) is about 1 inc. below carb. center...motor would run good with needle out 2.5 to 2.75 rich setting much past 3.75 motor would stop because of to rich setting## I tried the bisson pitts muffler (new slimline comming next week ) I noticed with the bisson the needle had to be out .5to.75 more to get same run ( richer )..tryed to tack motor but geebee would not work with barn lights##you could almost turn it out 4.75 turns before it would stop##motor rpm seemed faster then stock muffler.....but would not idel as well...I put stock muffler back on an decieded to try something runing at a rich setting needle 2.75 out and max thut..Ipulled muffler presser off the motor stopped int..##you could not get this motor to run good without muff. pressure evon with needle out 6 or more turns#### I have had other OS motors on this test stand that ran good without muff. pressure simple by turning needle out aturn or more###and some of them were not evon brokin in yet###IS THE FUEL DRAW LOW ON THESE MOTORS and this is the real design flow or problem with them##

I tryed something from the old race car days pressurize the fuel system>>>>I took an old spray can from a model car spray kit and hooked it up to the muffler line of the tank giving it about 1 to 2 lbs.of air ....started the motor and boy did it come to life just screamed I wish the tack would have work..must have been near 1000 rpm more needle vale was out about 1.75 turns and still running rich and one or two clicks would make a diffferance###Idle was better ..mid range trans.was great this idea brought the motor two life
IS THIS WHAT A PERRY PUMP WOULD DO?????? and if so dosent this prove that their is a design flaw in the fuel system of the OS91FX#######

HAS ANYONE USED A PERRY PUMP ON 91FX WITH STOCK CARB.AND NEEDLE SYSTEM??????? I have exstra back plate I can use but have to order perry nearest hobby store 100 mi,l.e but dose not stock it......are they ease to install and is there any problems with useing them????????

THANKS FOR YOUR TIME AND I HOPE IVE FOUND THE ANSWER