Spitting, banging, nasty, angry noise

Thanks to a lack of rain i was able to get the bike out today and balance the carbs. The design of the carbs means having to take the throttle tops off to access the linkages and make adjustments, this also make it very hard to run the bike on tickover, which is what you really want to balance them.
Anyway, none of them were miles out so i got that done without fuss.
There were problems with the offboard starter once again, but i'd rather have these problems now than at the start line in a race. I will have to make some modifications to it before going to the dyno next week.
While it was out i took the opportunity to test a few things. I wanted to check the clutch and gear change worked properly so i did a short burn out and took it for a gentle ride down the street!
I also tested the 2 step was working by making sure it hit the rev limiter with the clutch pulled in (5000rpm), it makes a spitting nasty angry noise on the limiter and shoots flames out! What happy neighbors i must have.

It has also become apparent that theres an oil leak from the cylinder head. Why this is i'm not sure, but i'll re-torque all the cylinder head bolts (something that is reccomended after an engine build anyway) and see if that helps. I dropped the oil out of the engine whilst it was still warm and will replace it with good quality fully synthetic stuff ready to race.