Exhaust pop on the up-shift

[Moakster]

My 05 Midnight has started a weird habit of having an exhaust pop on each up shift through the gears. Just a single pop on each shift. It it also has started to pop a little on decel but nothing real dramatic. Nothing loud. Any ideas. I do have the HD Road King pipes with the drilled out rear baffle plate and 4 drilled out holes in the inlet cone.

 

Moakster

[tmodel]

I also have an 05 but with stock exhaust. I was receiving a pop down shifting but would experience one during the shift sometimes too. I had the shop sync the carbs and both disappeared.

Edited July 7, 2008 by tmodel

[Guest tx2sturgis]

Carb Sync. AIS removal.

 

 

[mm482]

You may have an air leak in the exhaust system. I think there was a problem with the exhaust cracking on some of the 04 & 05s where the two exhaust pipes join together. Look for heat discoloration of the chrome at the Y.

Earl

86 VR

00 RSV

[adventurer 08]

i too have the same popping on my 08 with hd pipes if i up shift fast. if i shift just a little slower it does not pop. it just starting doing it about 2 weeks ago.

 

 

[V7Goose]

These are all classic signs of a vacuum leak on the intake - could be either cracked vacuum port caps or torn vacuum hoses to the AIS valve from careless maintenance while syncing the carbs. Popping on up shift is the same as popping on decel - chopping the throttle creates high vacuum and excess hydrocarbons in the exhaust track. ANY exhaust leak, such as the common problem with leaking Y joints, will exacerbate the problem. Since several of you mention you have an 05 model, I can say from personal experience that the vacuum port caps are almost certainly leaking if you have not replaced them. My 05 developed popping related to these caps last summer (2 1/2 years old). Check out the numerous other older threads on this subject for much more in-depth discussion of these causes and the fixes.

Goose

[Moakster]

Thanks Goose. The carbs were sync. before our South Dakota trip per the instructions from this site. I have not noticed any discoloration at the Y joint of either side exhaust, so i guess I will be getting new caps and see how that does. if that does not work then the AIS plug is next.

 

Moakster:confused24:

[V7Goose]

Just bring it over some time - I'm sure we can find the problem. I don't charge more than a 6-pack for the work!

Goose

[Moakster]

Thanks, I will get some time off in a week or two and get with you.

 

Moakster