Nutwagon,
I don't know what kind of throttle linkage these clone engines come with, and I never mess with them, so I've never converted one to twist throttle.
They aren't popular here in Miami...we don't have any kind of minibike culture here at all...it's all really serious kart racing...indoor and outdoor...lot's of high-dollar shifter karts and heavily modified 4-strokers...mostly American engine-based, but some Japanese made stuff.
We have about $6000-$8000 tied up in each of these karts, so nobody wants to 'experiment' with the performance or reliability of a Chinese engine.
Plus, even though everyone really does it, the last thing you want to do is give the appearance that you're 'goin' racin' on the cheap'...
Regardless of whether or not it's warranted, the guys who show up with the biggest dollar amount of toys get the reputation for being the 'serious' racers, and if anyone sees something on your karts that didn't cost as much as it possibly could, you get tagged as a wannabe...
I think it sucks, because kart racing is so much fun for kids, but the adults have to throw some ego into the mix and give it a negative side too. It's almost like 'if you're not spending as much as possible, don't even bother'.
So, I've posted before that I don't like these clone engines, and I'll probably never own one, but I have to make sure I don't hack on anybody else for running one...
If they work well for $100, you can't beat that...it's just that I'd hate to think some guy at B&S was getting laid off while some guy at Jhiang Dong was getting 37 cents and hour versus his standard rate of 25 cents an hour because he was on overtime, making stolen-design engines for the Capitalist Yankee Dogs.