Stromberg question

[TurboFource]

I can easily change back if there is an issue. I am concerned the fuel bowl will run dry as there is now just one carb feeding what was estimated as 200hp. On the R-Sport Volvos theyincreased the needle size and I think they were rated at 145hp.

On the two-strokes you referenced, did the electric pump increase fuel pressure requiring a decrease in surface area at the needle seat to prevent overriding the float?

The stock needle will flow enough fuel at 2.5psi for approximately 115hp (based on .5lbs of gas per hour per horsepower). My modified needle should flow enough fuel at 2.5psi for 220hp. (This is based on flow rate for water through an orifice, there would be some slight difference for gasoline.)

[jbcollier]

Basically, yes.  Most two wheeled carbs used to be fed by gravity so needle and seats were large as there was minimal pressure.  Performance 2T mostly use diaphragm pumps.  Pressure changes in the crankcase move a diaphragm which pumps the fuel.

[TurboFource]

It seems there is an easy way to tell if you have adjustable needles.

 It was hard to see down my damper tubes and there was a bunch of crud down there and the adjustment screw was stuck and wouldn't turn anyway so I wasn't sure if mine were adjustable until I took them apart....

So it appears that only air valves with adjustable needles have the top of the damper tube machined with the small slots for the adjustment tool to engage to prevent damage to the diaphragm during adjustment.