I've got a used (but low-hour) Brison 2.4 that I've just started putting in the air. I've been adjusting the needles to get what I think is just the right settings, but the mid range (transition point) never seems to get really clean.

Is this common?

Idle up to 1/3 runs great, 1/3 to 1/2 has that little "wurble" type sound in it, and then after 1/2 it sounds clean as a whistle - like a clean-running 2-cycle dirt bike enjoying its powerband.

Although I've tested in several places, I've got the low needle just a little richer than max lean - judging from the "acceleration test" when setting the low. High sounds very clean and adjustments on this didn't tremendously affect the transition as Brison says the low controls the transition.

I've been reading the posts in this forum on the pressures in the cowl and such but they don't sound exactly like what I've got... could be, but doesn't sound quite like the same problem. The "sputtering 50" thread has a little of the same characteristics but not quite the same.

So, anyone have a really clean mid-range?

Thanks!

-shaun