Managed to sort the spitting intake on the carb as well. In all honesty Jin should sell these as a kit so we know from ground up to check and recalibrate everything.
Long story short, I found out the intake valve qnd exhaust rods are too long , causing the valve opens too much and too long during the storke. There is an option to loosen the screws that hold the rocker arm to bring it a bit forward but that causes vacuum leak in the cylinder as there is no gasket in either two halves of the cylinders. ( next on my list to make custom gaskets )
The solution I chose was to make my own rods both for intake and exhaust valves. That way we eliminate too much scavenging during the stroke. I used .89 mm pushrod from a hobby shop, they seem to be a bit thicker and provide a better seating inside the rocket arms.
What I noticed was, each cylinder requires a different measurement rod due to massive margin of error when they build these engines. After all it's for display and hobby than a work horse. Many hours spent using trial and error method to find the correct lenght for each. The new rods as shorter by .40 ,.38 , .42 and .36 of a mm. But the difference is big in the small engine.
Now not only there is no dangerous spray and stink of fuel and out of the carb air intake but also much lower fuel consumption and less of oily soot out of the exhaust . Spark plugs( I am using Iridium type) look much cleaner too .
Maybe this can help someone else who experienced the same issue.
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