i thought on these bikes you were never suposed to hold the throttle open while trying to start it?
It won't very likely start that way in any case, but using the compression release, and holding the carb open at the same time you kick the engine through will blow out the excess fuel that's flooded the engine without drawing in any new fuel in the process. That's because there won't be enough air moving through the carb fast enough to create the necessary vacuum to raise fuel up through the jets.
This can also be done with auto decompression engines, but just turn it through slowly while doing so.
It may also be useful if the engine still acts flooded to open the throttle between 1/8 and 1/4 while cranking. The extra air will get it going. Just be aware there is a potential for it to kick back rather viciously.