What's the easiest way to get to plug wires off it's a very tight

 

With a spark plug removal plier.

 

I would think you'd need to pull the tank, or at least lift it at the seat. Not a big deal.

 

I removed the tank. I could have just lifted the tank, but removed it anyway. I just took some long needle-nose and pullet straight up. they will "pop" off.

 

Tank off and this:

 

You need to remove the tank completely. Try to run it down to about a gallon, so it will lift easier.

I bought a wire removal tool, but I found a set of 45-degree angle pliers worked better. The two outboard wires should pull off by hand, but do make sure you grip the cap on the hard part under the rubber. First time I did this, I lifted the rubber boot and it slid up the wire a couple of inches. Wiggle rapidly as you pull up. It will release itself surprisingly so be careful not to break anything. The fins on the cylinders are sharp so gloves will help.

The two inboard wires you will surely need the pliers or other tool. The caps and boots are different from the outboard. You can get your plier's teeth down below the wire, onto the hard plastic under the rubber, just under the mushroom head. Grasp, wiggle, pull up, and suddenly, WHAM!

I'm always afraid of damaging the wires, so I try not to stress them any more than necessary.

 

good stuff..and I really think one is ok following the manual for replacement interval 2 years or 30,000 miles unless there's a running issue..used to be soooo cheap and easy to replace on the TCs but with the M8 meeting the toughest emissions standards on the planet it seems they would be in good shape, as good spark plugs should be for that time and mileage..anyway, I'm not going to fuss over replacing them sooner

 

As has been mentioned elsewhere, it's apparently a good idea to check the spark plugs tightness on a new engine. Mine were loose. One plug, the outboard front cylinder, was not torqued at all. This was apparently a factory assembly issue. The sealing gasket on the plug was not fully crushed.

Throughout the years, every time I bought a new bike I would usually, unless it was fearfully hard to do, change the plugs within the break in period. Afraid that the plugs were not installed properly, the wrong type of plug, a broken plug, etc. I never found a problem until with this engine. Others have reported the same.

 

I replaced mine at ('17 RGU) at 25k miles. plugs looked new, but gaps had worn wider, of course. of course Murphy's law. I got finished and bike wouldn't start. I had visions of towing to dealer and humbly saying I was attempting to service it myself........................bend over please! I got settled down and got centered and realized I hadn't reconnected the fuel line into the bottom of the tank. no fuel, no start. live and learn, huh?

 

Yeah I noticed on my 2016 when I let a set of plugs go 20k miles, that there was obvious wear on the electrodes.

It makes me wonder why the long 30k mile interval. I don't think I've ever seen such a long interval on any other motorcycle. Most Japanese bikes that I've owned were 8k mile intervals, with real expensive plugs.

This interval with the Harley plugs is amazing to me. I can't imagine sticking to it. At $5 apiece, whenever I have my tank off I'm replacing plugs.