Dual tank mod??? Im not sure, but i would guess that with the two tanks, you may not have enough back pressure to feed the engine at the same rate it did before the mod. Post some pics of this setup, and any details. Im sure we can figure this out. You should be able to raise the idle a bit. NOT with your trim. If you need to raise the idle, and keep the clutch from engaging, then we can help you tune the clutch shoes too.

Matt