My 07 Ultra sometimes makes a brief whistle sound when I shut it off. It has a K&N air cleaner and V&H true duals. Other than that it's stock. Kinda sounds like a suckin in whistle instead of a blowin out whistle. It runs fine, just wondering if anyone has heard this before or have any ideas what it may be.

Thanks,

SugsPa

 

It is normal mine does it too. exhaust valve is open and it is sucking back through the exhaust. One cyl is coming up on compression and the other is on exhaust. With no fire on comp cyl the comp piston is forced back down and the ex piston sucks air in. Same pipes. Keeps the spiders on their toes.

 

...so thats what it is. Mine does it too but only since going to a stage 1. Never really affected anything so I just chalked it up to another one of those "normal" sounds. I just tell the chicks that the bike is whistling at them. Now I know.

 

haha Mine does it too...I always look around to see if my buddies hear it because it sounds funny.

 

Just my opinion but I think its the compression from the piston stopping at half compression and leaking back around the ring gaps, down into the crank case and up and out thru the ventilation breather system. The ventilation valves in the later model twin cam engines are rubber one way free flowing out poppet valves. The intake and exhaust valve if correct totally seal and will not leak by so it cannot be in exhaust pipe or intake throttle body. Besides the throttle body is close to air tight since the butterfly seats very well and the idle pintol valve from the IAC closes to prevent run-on and only opens and reset itself on the next key on. The suck-in in whistle is actually a sneeze and is the noise of air coming by the ring gaps echoing into crank case up and out the vents into the air filter.

Nice album Iron B on the starter gear

 

I definitley hear the sound through my left pipe (true duals like the OP). It is a short sucking in sound not blowing out. When the front cyl hits the compression and doesn't fire the engine goes backwards a half rev or so. With the front on comp the rear is on ex and right before TDC with the exhaust valve open and piston now going back down. Result is suck back through the exhaust. Almost straight through pipe so no restriction.


Thanks I want to post the starter gear pics on the original thread but I can't (havent had time) to hack how to post pics that are not thumbnails.
BTW All compensator knocking is still gone.

 

Its pretty normal. My '02 does it as well. FYI - It's got a 95" BB kit and a S&S 510G cam and all the related goodies. It runs like a raped ape, even with the whistle.

HD must have resolved the issues creating the whistle with the new framed bikes because my '10 doesn't do it.

 

Wow those pre 11' bikes sure had some weird peculiarities the list goes on and on: compensator, chain tensioners, what else hell who knows quit a love affair we have with these beasts huhh?

 

when my 07 ultra does it it is time to clean the air filter.