Saturday my wife and I went for a ride and we get to the end of our street and she says her bike (2018 Softail Slim) in making some type of noise, so we stop around the corner and I ride it around the block and it was definitely making some type of rattling noise up high but I couldn't quite pinpoint the source of the sound. So long story short we have a service manager ride it and he then switches out the gas cap under a warranty claim, seems there are a lot of gas caps that have been making a rattling noise, and actually if she had louder mufflers put on it would never have been noticed (she still has the original mufflers on). So if you have a rattling noise you can't quite figure out, ride it and push down on the cap to see if it stops the noise ( I was actually feeling around under the tank for something loose).

 

That's weird. They're really quiet when you set them on top of the gas pump.

 

f he switches to Valvoline 60W, all those noises will go away, and his bike will run forever...

Seriously, OP - thanks for the heads up!

 

It's common, mine's been replaced and so have other M8 Softails.

 

Been through 3 of them on my 96 two stock and one aftermarket. Therefore I will give the standard answer....they all do that.

 

Mines doing that on a 2017 Street Glide.

 

Yep. Known problem on some of the 2018 Softails. Fat Bob in particular. MoCo will swap em out for free, but who knows if the new ones are any better.....

A $10 aftermarket cap will fix the problem forever. Google "Rough Crafts gas cap".

 

You gotta be kidding ! My 15 was so tight you couldn't get it on and off without a struggle. now they are making them to loose ? Why can't they get a simple part correct ?

 

They are not loose, they are 2 piece and the plastic inner piece breaks and rattles. I found they break faster if you overtighten them.

 

Been an issue even back in the Evo days. The ratcheting mechanism loosens up with use and the caps rattle. I usually replace mine every few years. They're cheap enough from Drag Specialties.