I have a problem after spark plug replacement on my vespa et4 150cc 2000.
I installed NGK iridium spark plug, nothing else was done. I drove it one day and I noticed slight improvement, it run smoother, and starting was smoother.
Same day in the evening it slowly started to work bad, misfires, pops from exhaust and staling on idle.
I noticed crack on intake manifold which i tried to glue (picture), maybe false air is causing problem. I will replace it.
I also want to replace and install regular spark plug, not iridium.
Any toughs what could be the cause?
Thanks in advance.
