NGK B5HS works great and they are inexpensive or maybe you could try the next range cooler B6HS, but supposedly the Chinese stock plug is equivalent to the hotter B4HS...which I don't agree with....but the stock plug is slightly different than the NGK in construction and electrode tip length.What are the spark plugs that people have tried in these 2 stroke chinese engines. I have tried the champion cj7y, and didn't like it.
i replaced my plug and not much difference at all. the spark plug wire i changed and it made a huge difference
I am now going with a Champian L86c and I love the new sound I seem to be getting.
The plug is a bit too long and I may end up with probs. when I go to remove it but it did change the sound and feel of the bike, almost as if it is running a little richer now, from the sound of things. I have also used the "40501" which is what I seem to remember being an NGK but looking at it now, there is no "ngk" marking.