We have most guys at our track running Mega engines and lately or over the last 6 months i have seen and experienced the same with my DSII.
There seems to be carb issue with guys having to chage orings regularly as they get damaged fairly quickly.
I have run just on 6 liters on my DSII but have changed carb orings on 4 occassions know and have changed the carb now too.

So check it might be your problem too.