| The following examples are from my own bike (48cc) and online data for other bikes. This is my hobby bike and I know for certain it is jetted right. In case you haven't noticd yet I am definitely a perfectionist and if someone let's me ride their bike and it isn't jetted right I just hand it back to them. Only a well jetted bike to me is fun to ride because it never has weak spots in its powerband other than the pre pipe powerband which is normal if you don't have a correctly tuned boost bottle installed to correct that. The lean dip at 3/8 slide is exactly what I feel when testing it.  
Notice that this is a piston port intake engine which needs smaller jets because the vacuum pulse that reaches the carb is fairly strong since the port opens after developing strong negative pressure in the crankcase. Reed valved engines don't have as strong a pulse because they open up at the smallest amount of vacuum and so what reaches the carb is "smoother" in that there isn't a strong vacuum "front" to the pulse. Anyway you can see here that the jetting was a bit rich before 5/8 so if you were cruising around at half throttle then the exhaust note would be irregular and it would probably foul plugs if used as a trail bike. This could be corrected with a higher slide cutaway. Here's a video that allows you to hear it's low throttle richness (starting at 4:08): VIDEO  
The last example is of a Yamaha MX360 with VM34. This lucky bike had very good jetting.  
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