I remember once being a complete idiot and kicking over my Honda CR 250R Elsinore 2 stroke scramble bike with bare feet it backfired and the force from the kickstart rising back up on my right instep had it turn instant blue bruising with me barely able to walk at all afterwards.
I coined that bike "The all or nothing" so narrow was the power band your either going flat out or its bogged down over fueling itself but they were a very quick bike I had many spills on that thing but it was great fun.
I had a very similar mishap with my Gilera KZ 125.
One of the most intense feeling of pain I can remember...