Yeah Kt's dont have pull-starters, you could always skip the clutch, go direct drive and do the push-start thang, but that pretty much sucks...
That raptor engine you found needs a separate kart-starter just like those Kt's and My Star race engines. Like my Star, It also runs on Methanol (instead of gas) which is a hassle because you have to drain and flush the fuel tank/carb and also change the oil after every day of riding. Methanol allows race engines to be built to gain around 20% more power but it also requires much more maintenance to make-em last.
Your ebay BSP clone would be a cool choice but you could save quite a bit of money if you just bought it directly from the source at Arc racing instead:-->
http://www.arcracing.com/servlet/the-5/Box-Stock-Project-BSP/Detail
That ebay seller probably just buys those engines from Arc (w/the cheapo muffler) and marks-em up...
The Arc BSP engine doesn't come with a header, but you could order this one that comes with a MUCH better race style muffler and still save $$$:-->
http://www.arcracing.com/servlet/the-453/Box-Stock-Project-ARC/Detail
Arc has some better tuned/3-stage headers
on this page-->
http://www.arcracing.com/servlet/the-HP-Engine-Parts-&-Accessories/s/151/Categories
You realise those BSP clone engines come with a pulse fuel pump but need an external fuel tank right?
You could install a race style tank like one of these:-->
http://www.out2win.com/catalog/fueltanks.html
You could mount any type fuel tank anywhere you wanted. My karts fuel tank is mounted way down on the floor below the steering wheel, so you can see those pulse fuel pumps will draw fuel from just about anywhere that's convenient to mount your tank:
Its a good Idea to get the tank off the hot engine both for performance and safety reasons.
