Is There A Harley Davidson Mechanic In The House?

[RevRider]

Good Afternoon Board,

My son has a 2016 HD Dyna Street Bob, completely stock. It is garaged with me, I take it out regularly and I've noticed a "hiss sound" coming around on the air filter area. Upon inspection, I notice the following in the photo, one of the metal nipples had a black cap on, the other did not.
When I put my finger over the non-capped nipple, the hissing sound stopped, it was obviously drawing in air, I could feel the suction on my finger. I bought the cap, asked if a HD mechanic at the dealership could confirm it should be capped, and they could not answer as the Head Master Mechanic was not in today.

The HD part number is: 90383-98 Cap Plug, Induction Module.

Is there an HD Mechanic on our board that could properly advise me?

Thanks,

RevRider

 

[Astro14]

Anything that is between the filter and the engine, and that is sucking in air, would get a cap from me. No, I’m not a HD mechanic, but you’ve told me enough that I would cap it.

Unmetered air will make it run poorly. Unfiltered air, which is what I think this is, allows it to suck in dust and debris. No manufacturer intends for there to be an unfiltered vacuum leak…

 

[DuckRyder]

I’ve got a picture of an old rental with that air cleaner and it agrees with my knee jerk reaction, and Astro’s conclusion that of course it shouldn’t have a vacuum leak .

 

[RooflessVW]

For sure it should be capped, or a vacuum line connected.

Any modifications or loose vacuum lines?

 

[RevRider]

Big thank you for the quick responses!

Upon a further inspection, I found a loose hose just behind that connector point, I pictured it below.

I slid the hose over the nipple, it was the only "loose hose" available, and only 1 nipple uncovered, so I think they are a match for each other, and the sizing of the hose, i.e., diameter and length is a perfect match - so I think it's resolved.

Does anyone recommend I should have a mechanic double check this or ?

 

[RooflessVW]

Think you've got it

 

[BigCahuna]

If you have one handy, put a small ty rap on the hose to keep it from popping off again.,,

 

[RevRider]

Big thank you to all, I learned something today.

I wish I had more mechanical skills; my dad had them, my old brother had them, but I didn’t really get that gift; and I admire the folks that do have that skill set.

 

[bruckus]

I've replaced them on my bike a couple times. They get weathered, crack,leak and then like your sons just fall off.

 

[RevRider]

If you have one handy, put a small ty rap on the hose to keep it from popping off again.,,

Good idea, I do have those!