What are the limits to mounting a carb tilted?

Brad William /
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...as in not perpendicular. As in axially tilted. The carb throat remaining level, with the carb body tilted along that axis.

Maybe I'm not using the right search terms, but I can't find much on line about this.

The CV bings on my gravity fed BMW 650 are mounted with significant tilt on both axis. Its necessary because of their unusual placement (to say the least:((). Evidently it's not forbidden.

I just put a new carb on an e50. Its a little 16.5 mm carb designed as a Yamaha dt50 two stroke replacement. The yam is close enough in requirements and displacement to the e50 that I just mounted it with the needle and jetting out of the box, ran it, and adjusted from there. Very good so far. Plug chop good. Running temps fine. Idles fine. Check. Check. But it's fuel starving at WOT. Odd since I've experimented with half a dozen carbs on e50s in the past and never had this problem. It was necessary to tilt the carb a bit to shoehorn it in. But not more than 5 degrees.

I raised the float (sits lower with the carb held upside down) and it helped significantly, but it still starved at WOT. Maybe the float seat needs to be a little larger?

Its an OEM piston, cylinder. Its unlikely a delivery problem from the tank, petcock, line, since the previous carb ran fine ( but needed replacement). Ran with gas cap off. Still starved. Seems clear that the fuel level in the bowl just can't keep up with delivery. I'd expect that, perhaps, if the displacement had increased, but this is the OEM e50. (edited)

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