Vesp dr 180 kit

Currently running Dr 180 Kit on px125e disc, 28mm dellorto, Pm pipe with dellorto fuel pump, main jet is currently 130, reaches 50mph then dies, drop the throttle and away agian, back to 50mph the same again, is the jetting right or could it be the cold start mechanisum (choke) sticking on. help appreciated.

nick  

bigger main jet. cheers!

it seems that your having a fuel starvation. 

Would going a jet or jets higher help

thanks