Well--- here comes the broken record--
You don't start these engines by yourself.
You are fairly new at this - and have not seen - I guess, a person bleeding so badly you had to rip your shirt off and use it to control the arterial bleeding. then race to the emergency room.
I watch newbiees with 40's do the same trick you did - and I have done it myself -with small engines - so I know the panic of an engine trying to eat me.
I got cut by wimpy .29 controline engines - many years ago - so I learned when the danger was not as severe.
I now have someone hold my plane - always - no exceptions.
I occasionally started my ST1.4 setups by myself - but always considered it was at full throttle.
Last week - the throttle was bumped to half - so-- instant poweron my 40cc..
Even Electric models -with big 24 cell motors can be deadly - instant screaming power.
my big planes - simply put- no way will I trust anything.
This isn't an I told you so - just a comment which -hopefully will keep you from doing any harm to yourself.