Hesitation, now a back fire or have both?and its still backfiring.
Backfire ...
a backfire thru exhaust on a petrol engine lifting the foot off the throttle is lean mixture... or lpg when I was messing with very lean mixtures it didnt backfire....so not sure for LPG
A back fire thru the carb.. basic mechanics here....to ignite fuel in the inlet manifold/ carb will require a piont of ign.
This can only be a inlet valve open while it is firing.
To do this it is either
1/ not closing which could be over tight rocker adjustment or a VERY burnt inlet valve
2/Have a couple HT leads to spark plugs around the wrong way
3/Poor quality or abused by pulling on, old or burnt HT leads leaking electrons like water thru a hole causing misfire and/ or crossfire Simple to check on a dark night.
In my books If one cant with full confidence run your hand up and down HT leads, with the other hand on a good ground, while the engine is running then u should be doing something so u do.