I just changed plug wires and had a heck of a time with the "center" ones but it runs. Question, if they aren't seated and if it is firing just on the kickstand side plugs would I notice? Would it throw a code?

 

I put in all 4 new plugs, the right side overall is a pain. I have put on 200 miles and it runs great. But I was wondering about the same thing if the 2 right boots are not all the way in, would you notice anything wrong??

 

Here’s the codes for a ‘19. Which should be close enough. I don’t see a code for lack of or weak spark. Other than coil open or short, which would not be the same.

https://www.wilkinsharley.com/--Checking-Trouble-Codes-2019-Harley-David

 

why not remove he rear tank bolt, raise it slightly and check them out

 

I read early on in the M8 life that people were finding the plugs under the tank to be loose. So I changed my plugs early just to see. Sure enough, the were probably only finger tight. Did you find that?

 

Yes I did, 2 of them was just finger tight. The other 2 was just a little tight.

 

I got them in! it's easy to "miss the hole" and end up forcing the boot down the side of the plug instead of on the plug. It looks deep enough to be seated but it's not.

 

FYI a high performance builder told me that the SE wires didn't work as well as the stock HD wires. That was last fall, so I don't know if his opinion has changed or not... this was on a twin cam.

 

i di have any issue installing my SE wires, it helps to lift the tank.