Originally Posted by
Cat 1
Lonnie, Not sure what your curve looked like before but here is an idea - Just an Idea... What if you set the needles to have a low pulse width on the bottom and a long one on the top - the opposite of your flat curve - My single jet setups seem to tend this way (prior to E-pressure) - I'm wondering if the engine would transition better as the solenoid is doing more work and the carb metering less. If your curve is flat the carb tuning is doing the majority of the work - the electronic piece is less responsive in my mind.. I know the theory is a little "rough" but I would ty to see if it made a difference.
Exactly my thinking, but in reverse. I thought that perhaps with my curve looking more like a linear ramp, low pulse width at idle and high at wot, that I was asking the solenoid to do TOO much. To prove this out I messaged the needle settings to create 6 different curve profiles yesterday, that's why my tuning session took so long. In the end I discovered that the flatter the curve, the better, but only very slightly better and still not good enough. I feel something else is going on because, based on that experiment, the solenoid appears to do a pretty good job of keeping up with rapid changes in fuel demand even with a steep curve.
My 180 and 220 exhibit identical behaviour, they need very rich mixture settings to transition without leaning out i.e. requiring to be loaded up with excess fuel at any rpm above idle. With a 2 second slow up/slow down on the throttle channel I can get smooth transition if I quickly throttle up and down. If I pause at any rpm for more than 1/2 second transition problems begin. The longer I pause at any given rpm the worse it transitions. The fuel tank is deflating during these pauses, losing pressure and it's ability to provide excess fuel pressure for transition.
Next test will be with a rigid tank. If that doesn't fix the issue then I'll try Bert's trick of leading the throttle channel with the fuel channel by manipulating slow up/slow down rates.