Butre is a good guy and all, and he is not wrong, but in my experience, I'd level it or you will forever be chasing your tail.
About 5 years ago I stuck a bad arse KTM 250 motocross motor in to a little itsy-bitsy Yamaha Blaster.
This was the BADDEST KTM 250 made in the era, the feared 2003SX that killed Jeremy McGrath's motocross career.
It came with a widow-makin' 10hp light-switch jump in power at 6000rpm. Just what a Blaster needs, too much!
I digress...
So it was a tight fit and I angled it a bit to fit, including the carb.
Not such a bad angle, besides, the acceleration will make like nearly level right?
The theory is you just adjust the float level and jet it for this position. WELL!
You do not have enough time in life to get the bugs out of a crooked carb. LEVEL IT.
I'm not a dumb guy, and you don't need all the woe it took for me to get to this life lesson.
Works MUCH better like this.
Works so smooth now, I can relax on outings...
I think I've soiled my pants...
Steve